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mpr03x rev 2.0 11/2008 freescale semiconductor technical data preliminary ? freescale semiconductor, in c., 2008. all rights reserved. this document contains a product under development. freescale semiconducto r reserves the right to change or discontinue this product without notice. product preview proximity capacitive touch sensor controller mpr03x overview the mpr03x is an inter-integr ated circuit communication (i 2 c) driven capacitive touch sensor controller, optimized to manage two electrodes with interrupt functional ity, or three electrodes with the interrupt disabled. it can accommodate a wide range of implementations due to increased sensitivity and a specialized feature set. features ? 8 a supply current with two electrodes being monitored with 64 ms response time and irq enabled ? compact 2 x 2 x 0.65 mm 8-lead dfn package ? supports up to 3 touch pads ? only one external component needed ? intelligent touch detection capacity ? 4 a maximum shutdown current ? 1.71 v to 2.75 v operation ? threshold based detection with hysteresis ?i 2 c interface, with optional irq ? multiple devices in a system allo w for up to 6 electrodes (need MPR032 with second i 2 c address) ? -40c to +85c operating temperature range implementations ? switch replacements ? touch pads typical applications ? pc peripherals ? mp3 players ? remote controls ? mobile phones ? lighting controls ordering information device name temperature range case number touch pads i 2 c address shipping mpr031ep -40 c to +85 c 1944 (8-pin udfn) 3-pads 0x4a bulk mpr031epr2 -40 c to +85 c 1944 (8-pin udfn) 3-pads 0x4a tape and reel MPR032ep -40 c to +85 c 1944 (8-pin udfn) 3-pads 0x4b bulk MPR032epr2 -40 c to +85 c 1944 (8-pin udfn) 3-pads 0x4b tape and reel mpr031 MPR032 capacitive touch sensor controller top view figure 1. pin connections bottom view 8-pin udfn case 1944 1 scl 2 3 8 7 6 5 4 sda v ss v dd irq /ele2 ele1 ele0 rext mpr03x interface i 2 c serial v ss sda scl mpr03x ele0 ele1 v dd int 1 2 v ss 75k rext mpr03x with 2 electrodes and 2 pads
mpr03x sensors 2 freescale semiconductor preliminary 1 device overview 1.1 introduction mpr03x is a small outline, low profile, lo w voltage touch sensor controller in a 2 mm x 2 mm dfn which manages up to three touch pad electrodes. an i 2 c interface communicates with the host controller at data rates up to 400 kbits/sec. an optional interrupt output advises the host of electrode status changes. the interrupt output is a multip lexed with the third electrode o utput, so using the interrupt output reduces the num ber of electrode inputs to two. the mpr03x includes three levels of input signal filtering to detect pad input condition changes due to touch without any processing by the application. 1.2 internal block diagram figure 2. functional block diagram ele0 ele1 ele2 0 1 2 012 current source multiplexor input source multiplexor iref 3 set source curr ent mi rr or iset select chan select chan set input channel sel set grounded electrodes 10 bit adc enable convert clock data 10 adc result 8mhz star t conver sion shutdown 2 4 2 interrupt controller i2c interface 32 khz oscillator user registers debounced results magnitude comparator averag e filtered debounce result debounce filter registers 4 x max registers 4 x sum registers 4xminregisters sda scl irq set clr shutdown debounce interval debounce count sample interval sample count debounce and sample counters average filtered sample result sample filter registers max r egister sum register min r egister set source curr ent set input channel adc result 8mhz star t conver sion shutdown 8mhz oscillator shutdown adc c on tr o ller traffic sda scl irq 32 khz8 mhz set grounded electrodes number of electrodes un-touched baseline filter 0v rext
mpr03x sensors freescale semiconductor 3 preliminary 2 external signal description 2.1 device pin assignment ta b l e 1 shows the pin assignment for the mpr03x. for a more detailed description of the functionality of each pin, refer to the appropriate chapter. the package available for the mpr03x is a 2 x 2 mm 8 pin udfn. the package and pinout is shown in figure 3 . figure 3. package pinouts 2.2 recommended s ystem connections the mpr03x capacitive touch sensor controller requ ires one external passive component. as shown in ta b l e 1 , the rext line should have a 75 k ? connected from the pin to gnd. this resistor needs to be 1% tolerance. in addition to the one resistor, a bypass capacitor of 10f should always be used between the v dd and v ss lines and a 4.7 k ? pull-up resistor should be included on the irq . the remaining three connections are scl, sda, irq . depending on the specific application, each of these control lines can be used by connecting them to a host controller. in the most mi nimal system, the scl and sda must be connected to a master i 2 c interface to communicate with the mpr03x. all of the co nnections for the mpr03x are shown by the schematic in figure 4 . figure 4. recommended system connections schematic table 1. device pin assignment pin name function 1scl i 2 c serial clock input 2sda i 2 c serial data i/o 3v ss ground 4v dd positive supply voltage 5 rext reference resistor connect a 75 k ? 1% resistor from rext to v ss 6 ele0 electrode 0 7 ele1 electrode 1 8irq /ele2 interrupt output or touch electrode input 2 irq is the active-low open-drain interrupt output 1 scl 2 3 8 7 6 5 4 sda v ss v dd irq /ele2 ele1 ele0 rext mpr03x interface i 2 c serial 3 v ss sda scl mpr03x ele0 ele1 irq/ele2 1 2 v ss 75k v dd rext
mpr03x sensors 4 freescale semiconductor preliminary 2.3 serial interface the mpr03x uses an i 2 c serial interface. the i 2 c protocol implementation and the specifics of communicating with the touch sensor controller are detailed in the following sections. 2.3.1 serial-addressing the mpr03x operates as a slave that sends and receives data through an i 2 c 2-wire interface. the inte rface uses a serial data line (sda) and a serial clock line (scl) to achieve bi-direc tional communication between mast er(s) and slave(s). a master (typically a microcontroller) initiates all data transfers to and from the mpr03x, and it generat es the scl clock that synchron izes the data transfer. the mpr03x sda line operates as both an input and an open-drain output. a pull-up resistor, typically 4.7k ? , is required on sda. the mpr03x scl line operates only as an input. a pull-up resistor, typically 4.7k ? , is required on scl if there are multiple masters on the 2-wire interface, or if the master in a single-master system has an open-drain scl output. each transmission consists of a start condition ( figure 5 ) sent by a master, followed by the mpr03x?s 7-bit slave address plus r/w bit, a register address byte, one or more data bytes, and finally a stop condition. figure 5. wire serial interface timing details 2.3.2 start and stop conditions both scl and sda remain high when the interface is not busy . a master signals the beginning of a transmission with a start (s) condition by transitioning sda from high to low while scl is high. when the master has finished communicating with the slave, it issues a stop (p) condition by transitioning sda from low to high while scl is high. the bus is then free for ano ther transmission. figure 6. start and stop conditions 2.3.3 bit transfer one data bit is transferred during each clock pulse ( figure 7 ). the data on sda must remain stable while scl is high. scl sda t low t high t f t r t hd sta t hd dat t hd sta t su dat t su sta t buf t su sto start condit ion stop condit ion repeated start condit ion start condit ion data line stable data valid change of data allowed sda scl
mpr03x sensors freescale semiconductor 5 preliminary figure 7. bit transfer 2.3.4 acknowledge the acknowledge bit is a clocked 9 th bit ( figure 8 ) which the recipient uses to handshake rece ipt of each byte of data. thus each byte transferred effectively requires 9 bits. the master generates the 9 th clock pulse, and the recipient pulls down sda during the acknowledge clock pulse, such that the sda line is stable lo w during the high period of the clock pulse. when the master is transmitting to the mpr03x, the mpr03x gener ates the acknowledge bit, since the mpr0 3x is the recipient. when the mpr03x is transmitting to the master, the master generates t he acknowledge bit, since the master is the recipient. figure 8. acknowledge 2.3.5 the slave address the mpr03x has a 7-bit long slave address ( figure 9 ). the bit following the 7-bit slave address (bit eight) is the r/w bit, which is low for a write command and high for a read command. figure 9. slave address the mpr03x monitors the bus continuously , waiting for a start condition followed by its slave address. when a mpr03x recognizes its slave address, it acknowledges a nd is then ready for continued communication. the mpr031 and MPR032 slave addresses are show in table 2 . table 2. part number i 2 c address mpr031 0x4a MPR032 0x4b start condition sda scl stop condition p s start condition sda by transmitter s 12 89 clock pulse for acknowledgement sda by receiver scl sda 1 r/w ack msb scl 01 0010
mpr03x sensors 6 freescale semiconductor preliminary 2.3.6 message format for writing the mpr03x a write to the mpr03x comprises the transmission of the mpr03x?s keyscan slave address with the r/w bit set to 0, followed by at least one byte of information. t he first byte of information is the comm and byte. the command byte determines which register of the mpr03x is to be written by the next byte, if re ceived. if a stop condition is detected after the command byte i s received, the mpr03x takes no further action ( figure 10 ) beyond storing the command byte. any bytes received after the command byte are data bytes. figure 10. command byte received any bytes received after the command byte are data bytes. the firs t data byte goes into the internal register of the mpr03x selected by the command byte (figure 11) . figure 11. command and single data byte received if multiple data bytes are transmitted bef ore a stop condition is det ected, these bytes are generally stored in subsequent mpr03x internal registers because the command byte address generally auto-increments (section 2.4) . 2.3.7 message format for reading the mpr03x mpr03x is read using mpr03x's internally stored register addr ess as address pointer, the same way the stored register address is used as address pointer for a write. the pointer generally auto -increments after each data byte is read using the same rules as for a write (table 5) . thus, a read is initiated by first configuring mpr03x's register address by performing a write (figure 10) followed by a repeated start. the master can now read 'n' consecutiv e bytes from mpr03x, with first data byte being read from the register addressed by the in itialized register address. figure 12. reading mpr03x saap 0 slave address command byte acknowledge from mpr03x r/w acknowledge from mpr3x d15 d14 d13 d12 d11 d10 d9 d8 commandbyteisstoredonreceiptofstopcondition sa aap 0 sl ave address command byt e data byt e acknowledge from mpr03x r/w 1byte auto-i ncrement memory word address d15 d14 d13 d12 d11 d10 d9 d8 d1 d0 d3 d2 d5 d4 d7 d6 how command byte and data byte map into mpr03x's registers acknowledge from mpr03x acknowledge from mpr03x saap 1 slave address data byt e r/w n bytes auto-i ncrement memory word address d1 d0 d3 d2 d5 d4 d7 d6 acknowledge from mpr03x acknowledge from master
mpr03x sensors freescale semiconductor 7 preliminary 2.3.8 operation with multiple master the application should use repeated starts to addr ess the mpr03x to avoid bus confusion between i 2 c masters.on a i 2 c bus, once a master issues a start/repeated start condition, that mast er owns the bus until a stop c ondition occurs. if a master that does not own the bus attempts to take control of that bus, then impr oper addressing may occur. an address may always be rewritten to fix this problem. follow i 2 c protocol for multiple master configurations. 2.4 register address map table 3. register address map register register address burst mode auto-increment address touch status register 0x00 register address + 1 ele0 filtered data low register 0x02 ele0 filtered data high register 0x03 ele1 filtered data low register 0x04 ele1 filtered data high register 0x05 ele2 filtered data low register 0x06 ele2 filtered data high register 0x07 ele0 baseline value register 0x1a ele1 baseline value register 0x1b ele2 baseline value register 0x1c max half delta register 0x26 noise half delta register 0x27 noise count limit register 0x28 ele0 touch threshold register 0x29 ele0 release threshold register 0x2a ele1 touch threshold register 0x2b ele1 release threshold register 0x2c ele2 touch threshold register 0x2d ele2 release threshold register 0x2e afe configuration register 0x41 filter configuration register 0x43 electrode configuration register 0x44 0x00
mpr03x sensors 8 freescale semiconductor preliminary 3 functional overview 3.1 introduction the mpr03x has an analog front, a digital filter, and a touch re cognition system. this data interpretation can be done many different ways but the method used in the mpr03x is explained in this chapter. 3.2 understanding the basics mpr03x is a touch pad controller which manages two or three touch pad electrodes. an i2c interface communicates with the host, and an optional interrupt output advi ses the host of electrode stat us changes. the interrupt output is a multiplexed func tion with the third electrode input, so using the interrupt output reduces the number of electrode inputs to two. the primary application for mpr03x is the management of user interfac e touch pads. monitoring touch pads involves detecting small changes of pad capacitance. mpr03x incorporates a se lf calibration function which c ontinually adjusts the baseline capacitance for each individual electrode. therefore, the host on ly has to configure the delta thresholds to interpret a touch or release. mpr03x uses a state machine to operate a capacitive measurem ent engine to analyze the electrodes and determine whether a pad has been touched or released. between measurements the mpr03x draws negligible current. the application controls mpr03x's configuration, making trade-offs between nois e rejection, touch response time, and power consumption. 3.3 implementation the touch sensor system can be tailored to specific applications by varying the follo wing: a capacitance detector, a raw data l ow pass filter, a baseline m anagement system, and a touc h detection system. in the following sections , the functi onality and configuration of each block will be described. electrodes can be connected to the mpr03x in two different configurations, one with an irq and one without ( figure 13 ). figure 13. mpr03x pad and interrupt connection options 1 2 3 ele0 ele1 ele2 interface i 2 c serial v ss sda scl mpr03x ele0 ele1 v dd int 1 2 sda scl mpr03x v dd interface i 2 c serial v ss v ss 75k rext v ss 75k rext mpr03x with 2 electrodes and 2 pads mpr03x with 3 electrodes and 3 pads
mpr03x sensors freescale semiconductor 9 preliminary 4 modes of operation 4.1 introduction mpr03x?s operation modes are stop, run1, and run2. stop mode is the start-up and configuration mode. 4.2 stop mode in stop mode, the mpr03x does not monitor any of t he electrodes. this mode is the lowest power state. 4.2.1 initial power up on power-up, the device is in stop mode, registers are reset to the initial values shown in table 4 , and mpr03x starts in stop mode drawing minimal supply current. the user configurable pin irq /ele2 defaults to being the interrupt output irq function. irq is reset on power-up, and so defaults to logic high. since the irq is an open-drain output, irq will be high impedance. 4.2.2 stop mode usage in order to set the configuration registers, the device must be in stop mode. this is achieved by setting the eleen field in th e electrode configuration register to zero. table 4. power-up register configurations register power-up conditio n register address hex value touch status register cleared 0x00 0x00 ele0 filtered data low register cleared 0x02 0x00 ele0 filtered data high register cleared 0x03 0x00 ele1 filtered data low register cleared 0x04 0x00 ele1 filtered data high register cleared 0x05 0x00 ele2 filtered data low register cleared 0x06 0x00 ele2 filtered data high register cleared 0x07 0x00 ele0 baseline value register cleared 0x1a 0x00 ele1 baseline value register cleared 0x1b 0x00 ele2 baseline value register cleared 0x1c 0x00 max half delta register max half delta set to 1 0x26 0x00 noise half delta register noise half delta amount set to 1 0x27 0x00 noise count limit register noise count limit set to 1 0x28 0x00 ele0 touch threshold register threshold set to 1 0x29 0x00 ele0 release threshold register threshold set to 1 0x2a 0x00 ele1 touch threshold register threshold set to 1 0x2b 0x00 ele1 release threshold register threshold set to 1 0x2c 0x00 ele2 touch threshold register threshold set to 1 0x2d 0x00 ele2 release threshold register threshold set to 1 0x2e 0x00 afe configuration register 6 afe samples, 16a c harge current 0x41 0x08 filter configuration register 6 touch detection samples, 16ms detection sample interval 0x43 0x04 electrode configuration register stop mode. ele2/irq pin is interrupt function, 0x44 0x00
mpr03x sensors 10 freescale semiconductor preliminary 4.3 run1 mode in run1 mode, the mpr03x monitors 1, 2, or 3 electrodes which are connected to a us er defined array of touch pads. when only 1 or 2 electrodes are selected, the irq /ele2 pin is automatically configured as an open drain interrupt output. when 3 electrodes are selected in run1 mode, the irq /ele2 pin becomes the third electrode input, ele2 ( figure 14 ). figure 14. electrode/pad connections in run mode 4.4 run2 mode in run2 mode, all enabled electrodes act as a single electrode by internally connecting the el ectrode pins together. the entire surface of all the touch pads is used as a sing le pad, increasing the total area of the conductor. when 2 electrodes are selected in run2 mode, the irq /ele2 pin is automatically configured as an open drain interrupt output. when 3 electrodes are selected, the irq /ele2 pin becomes the third electrode input, ele2 ( figure 15 ). figure 15. electrode/pad connections in area detection mode 4.5 electrode configuration register the electrode configuration register manages the configuration of the electrode outputs in addition to the mode of the part. th e address of the electrode configuration register is 0x44. figure 16. electrode configuration register 76543210 r0 callock modesel eleen w reset:00000000 = unimplemented ele0 ele1 capacitance measurement engine filters and touch detection ele2 3 1 2 run1 mode with 3 electrodes int interrupt run1 mode with 2 electrodes ele1 ele0 capacitance measurement engine filters and touch detection 1 2 int interrupt run1 mode with 1 electrode ele0 capacitance measurement engine filters and touch detection 1 ele0 ele1 int capacitance measurement engine filters and touch detection ele2 interrupt run2 mode to 2 pads 3 1 2 ele1 ele0 capacitance measurement engine filters and touch detection run2 mode to 3 pads 1 2
mpr03x sensors freescale semiconductor 11 preliminary table 5. electrode configuration register field descriptions field description 6 callock calibration lock ? the calibration lock bit selects whether calibration is enabled or disabled. 0 enabled ? in this state baseline calibration is enabled. 1 disabled ? in this state baseline calibration is disabled. 5:4 modesel mode select ? the mode select field selects which run mode the sensor will operate in. this register is ignored when in stop mode. 00 encoding 0 ? run1 mode is enabled. 01 encoding 1 ? run2 mode is enabled. 10 encoding 2 ? run2 mode is enabled. 11 encoding 3 ? run2 mode is enabled. 3:0 eleen electrode enable ? the electrode enable field selects the electrode and irq functionality. 0000 encoding 0 ? stop mode 0001 encoding 1 ? run mode with ele0 is enabled, ele1 is disabled, irq is enabled. 0010 encoding 2 ? run mode with ele0 is enabled, ele1 is enabled, irq is enabled. 0011 encoding 3 ? run mode with ele0 is enabled, ele1 is enabled, ele2 is enabled. ~ 1111 encoding 15 ? run mode with ele0 is enabled, ele1 is enabled, ele2 is enabled.
mpr03x sensors 12 freescale semiconductor preliminary 5 output mechanisms 5.1 introduction the mpr03x has three outputs: the touch status, values from the second level filter ( section 8.3 ), and the calibrated baseline values. the application can either use the touch status or a combination of sec ond level filter data with the baseline data to determine when a touch occurs. 5.2 touch status each electrode has an associated single bit that denotes whether or not the pad is currently touc hed. this output is generated using the touch threshold and release threshold registers to determine when a pad is considered touched or untouched. configuration of this system is discussed in section 9 . 5.2.1 touch status register the touch pad status register is a re ad only register for determining the cu rrent status of the touch pad. the i 2 c slave address of the touch pad status register is 0x02. figure 17. touch status register 7 6 543210 r ocf 0 0 0 0 e2s e1s e0s w reset:0 0 000000 = unimplemented table 6. touch pad status register field descriptions field description 7 ocf over current flag ? the over current flag shows when too much current is on the rext pin. if it is set all other status flags and regi sters are cleared and the device is set to stop mode. when ocf is set, the mpr03x cannot be put back into a run mode. 0 ? current is within limits. 1 ? current is above limits. writing a 1 to this field will clear the ocf. 2 e2s electrode 2 status ? the electrode 2 st atus bit shows touched or not touched. 0 ? not touched 1 ? touched 1 e1s electrode 1 status ? the electrode 1 st atus bit shows touched or not touched. 0 ? not touched 1 ? touched 0 e0s electrode 0 status ? the electrode 0 st atus bit shows touched or not touched. 0 ? not touched 1 ? touched
mpr03x sensors freescale semiconductor 13 preliminary 5.3 filtered data each electrode has an associated filtered output. this output is gene rated through register settings and a low pass filter implementation ( section 8.4 ). 5.3.1 filtered data low register the filtered data low register contains the data on each of the el ectrodes. it is paired with the filtered data high register f or reading the 10 bit a/d value. the address of the ele0 filtered data low register is 0x02. the addr ess of the ele1 filtered data low register is 0x04. the address of the ele2 filtered data low register is 0x06. figure 18. filtered data low register 5.3.2 filtered data high register the filtered data high register contains t he data on each of the electrodes. it is paired with the filtered data low register f or reading the 10 bit a/d value. the address of the ele0 filtered data high register is 0x03. the address of the ele1 filtered dat a high register is 0x05. the address of the ele2 filtered data high register is 0x07. figure 19. filtered data high register 7 6 543210 rfdlb w reset:0 0 000000 = unimplemented table 7. filtered data low register field descriptions field description 7:0 fdlb filtered data low byte ? the filtered data low byte displays the lower 8 bits of the 10 bit filtered a/d reading. 00000000 encoding 0 ~ 11111111 encoding 255 7 6 543210 r0 0 0000 fdhb w reset:0 0 000000 = unimplemented table 8. filtered data high register field descriptions field description 7:0 fdhb filtered data high bits ? the filtered data high bits displays the higher 2 bits of the 10 bit filtered a/d reading. 00 encoding 0 ~ 11 encoding 3
mpr03x sensors 14 freescale semiconductor preliminary 5.4 baseline values in addition to the second level filter dat a, the data from the baseline filter (or th ird level filter) is also displayed. in th is case, the least two significant bits are removed before the 10-bit value is displayed in the register. 5.4.1 baseline value register the baseline value register contains the third level filtered da ta on each of the electrodes. it is a truncated 10 bit a/d valu e displayed in the 8 bit register. the address of the ele0 baseli ne value register is 0x1a. the address of the ele1 baseline valu e register is 0x1b. the address of the ele2 baseline value register is 0x1c. figure 20. filtered data high register 7 6 543210 rbv w reset:0 0 000000 = unimplemented table 9. filtered data high register field descriptions field description 7:0 bv baseline value ? the baseline value byte displays the higher 8 bits of the 10 bit baseline value. 00000000 encoding 0 ? the 10 bit baseline value is between 0 and 3. ~ 11111111 encoding 255 ? the 10 bit baseline value is between 1020 and 1023.
mpr03x sensors freescale semiconductor 15 preliminary 6 interrupts 6.1 introduction the mpr03x has one interrupt output that is triggered on any touch related event. the interrupts trigger on both the up or down motion of a finger as defined by a set of configurable thresholds. 6.2 triggering an interrupt an interrupt is asserted any time data ch anges in the touch status register ( section 5.2 ). this means that if an electrode touch or release occurs, an interrupt will alert the application of the change. 6.3 interrupt handling the mpr03x has one interrupt output that is asserted on any t ouch related event. the interrupts trigger on both the up or down motion of a finger as defined by a set of configurable thresholds as described in section 9 . to service an interrupt, the application must read the touch status register ( section 5.2 ) and determine the current condition of the system. as soon as an i 2 c read takes place the mpr03x will release the interrupt. 6.4 irq pin the irq pin is an open-drain latching interrupt output which requi res an external pull-up resistor. the pin will latch down based on the conditions in section 6.2 . the pin will de-assert when an i 2 c transaction reads from the mpr03x.
mpr03x sensors 16 freescale semiconductor preliminary 7 theory of operation 7.1 introduction the mpr03x utilizes the principl e that a capacitor holds a fixed amount of charge at a specific electric potential. both the implementation and the configuration will be described in this section. 7.2 capacitance measurement the basic measurement technique used by the mpr03x is to charge up the capacitor c on one electrode input with a dc current i for a time t (the charge time). before measurement, the elec trode input is grounded, so the el ectrode voltage starts from 0 v and charges up with a slope, equation 1 , where c is the pad capacitance on the electrode ( figure 21 ). all of the other electrodes are grounded during this measurement. at t he end of time t, the electrode voltage is measured with a 10 bit adc. the voltage is inversely proportional to capacitance according to equation 2 . the electrode is then discharge d back to ground at the same rate it was charged. equation 1 equation 2 figure 21. mpr03x electrode measure ment charging pad capacitance when measuring capacitance there are some inherent restricti ons due to the methodology used. on the mpr03x the voltage after charging must be in the range that is shown in figure 22 . figure 22. c i dt dv = c t i v = electrode charge time t v electrode voltage electrode charging electrode discharging electrode voltage measured here 2t electrode discharge time valid adc values vs. v dd 0 100 200 300 400 500 600 700 800 900 1.71 1.91 2.11 2.31 2.51 2.71 v dd (v) adc counts adchigh adcmid adclow
mpr03x sensors freescale semiconductor 17 preliminary the valid operating range of the elec trode charging source is 0.7v to (v dd -.7)v. this means that for a given v dd the valid adc (voltage visible to the digital interface) range is given by , equation 3 and . equation 4 these equations are represented in the graph. in the nominal case of v dd = 1.8v the adc range is shown below in ta b l e 1 0 . any adc counts outside of the range shown are invalid and settin gs must be adjusted to be withi n this range. if capacitance variation is of importance for an application after the curren t output, charge time and supply voltage are determined then the following equations can be used. the valid range for capacitance is calculated by using the minimum and maximum adc values in the capacitance equation. substituting the low and high adc equations into the capacitance equation yields the equations for the minimum and maximum capa citance values which are and . equation 5 7.3 sensitivity the sensitivity of the mpr03x is relative to the capacitanc e range being measured. given th e adc value, current and time settings capacitance can be calculated, . equation 6 for a given capacitance the sensitivity can be measured by taking the derivative of this equation. the result of this is the following equation, representing the change in capacitance per one adc count, where the adc in the equation represents the current value. equation 7 this relationship is shown in the following graph by taking the midpoints off all possible ranges by varying the current and ti me settings. the midpoint is assumed to be 512 for a dc and the nominal supply voltage of 1.8v is used. table 10. vdd adchigh adclow adcmid 1.8 625.7778 398.2222 512 () 1024 7 . dd low v adc = () () 1024 7 . dd dd high v v adc ? = 7 . ? = dd low v t i c 7 . t i c high = adc v t i c dd = 1024 2 1024 adc v t i dadc dc dd ? =
mpr03x sensors 18 freescale semiconductor preliminary figure 23. smaller amounts of change indicate increas ed sensitivity for the capacitance sens or. some sample values are shown in ta b l e 11 . in the above cases, the capacitance is assumed to be in the midd le of the range for specific settings. within the capacitance range the equation is nonlinear, thus the sens itivity is best with the lowest capacit ance. this graph shows the sensitivity der ivative reading across the valid range of capacitances for a set i, t, and v dd . for simple small electrodes (that are approximately 21 pf) and a nominal 1.8v supply the following graph is representative of this effect. figure 24. table 11. pf sensitivity (pf/adc count) 10 -0.01953 100 -0.19531 sensitivity vs. midpoint capacitance for v dd =1.8v -5 -4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 500 1000 1500 2000 2500 midpoint capacitance (pf) sensitivity (pf/adc count) dc/dadc @cmid (pf/1 adc count) 0 sensitivity vs. capacitance for v dd =1.8vandi=36 aandt=.5 s 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 10 12 14 16 18 20 22 24 26 28 30 sensitivity (pf/adc count) maximum minimum c/adc capacitance
mpr03x sensors freescale semiconductor 19 preliminary 7.4 configuration from the implementation above, there are two elements that can be configured to yi eld a wide range of capacitance readings ranging from 0.455 pf to 2874.39 pf. the two configurable components are the electrode charge current and the electrode charge time. the electrode charge current can be configur ed to equal a range of values between 1 a and 63 a. this value is set in the cdc in the afe configuration register ( section 7.4.1 ). the electrode charge time can be configured to equal a range of values between 500 ns and 32 s. this value is set in the cdt in the filter configuration register ( section 8.3.1 ). 7.4.1 afe configuration register the afe (analog front end) configuration register is used to se t both the charge/discharge current and the number of samples taken in the lowest level filter. the address of the afe configuration register is 0x41. figure 25. afe configuration register 7 6 543210 r ffi cdc w reset:0 0 000000 = unimplemented table 12. afe configuration register field descriptions field description 7:6 ffi first filter iterations ? the first filter it erations field selects the number of samples taken as input to the fi rst level of filtering. 00 encoding 0 ? sets samples taken to 6 01 encoding 1 ? sets samples taken to 10 10 encoding 2 ? sets samples taken to 18 11 encoding 3 ? sets samples taken to 34 5:0 cdc charge discharge current ? the charge discharge current field selects the supply current to be used when c harging and discharging an electrode. 000000 encoding 0 ? disables electrode charging 000001 encoding 1 ? sets the current to 1ua ~ 111111 encoding 63 ? sets the current to 63ua
mpr03x sensors 20 freescale semiconductor preliminary 8filtering 8.1 introduction the mpr03x has three levels of filtering. the first and second level filters will allow the application to condition the signal for undesired input variation. the third level f ilter can be configured to reject touch stimulus and be used as a baseline for touc h detection. each level of f iltering will be further described in this section. 8.2 first level the first level filter is designed to filter high frequency noi se by averaging samples taken over short periods of time. the nu mber of samples can be configured to equal a set of values ranging from 6 to 34 samples. this value is set by the ffi in the afe configuration register ( section 7.4.1 ). the timing of this filter is determined by t he configuration of the el ectrode charge time in the filter configuration register ( section 8.3.1 ). note that the electrode charge time must be configured for the capacitance in the ap plication. the resulting value will affect the period of the first level filter. 8.3 second level the second level filter is designed to filt er low frequency noise and reject false to uches due to inconsistent data. the number of samples can be configured to equal a set of values ranging from 4 to 18. this value is set by the sfi in the filter configurati on register ( section 8.3.1 ). the timing of this filter is determined by the conf iguration of esi in the filt er configuration register ( section 8.3.1 ). note that the esi (electrode sample interval) must be conf igured to accommodate the low power requirements of a system. thus, the resulting value will affect the period of the second level filter. the raw data from the second level of filt ering is output in the filtered data high a nd filtered data low registers, as shown i n section 5.3 . 8.3.1 filter configuration register the filter configuration register is used to set. the address of the electr ode configuration register is 0x43. figure 26. filter configuration register 7 6 543210 r cdt sfi esi w reset:0 0 000000 = unimplemented
mpr03x sensors freescale semiconductor 21 preliminary 8.4 third level filter the third level filter is designed for varying implementations. it can be used as either an additi onal low pass filter for the electrode data or a baseline for touch detecti on. for it to function as a baseline filter, it must be used in conjunction with the touch detection system described in the next chapter . to use the filter as an additional laye r for low pass filtering, the touch dete ction system must be disabled by setting all of the touch thre sholds to zero (refer to section 9.2 ). although, in most cases the third level of filter will be used as a baseline filter. the primary difference between thes e implementations is this: if a touch is detected the baseline filter will hold its current value until the touch is released. the touch/releas e configuration will be described in chapter 9 . when a touch is not currently de tected, the baseline filter will operate based on a few conditions. these are configured throug h a set of registers including the max half delta register, the noise half delta register, and the noise count limit. 8.4.1 max half delta register the max half delta register is used to set the max half delta for the third level filter. the address of the max half delta reg ister is 0x26. figure 27. max half delta register table 13. filter configuration register field descriptions field description 7:5 cdt charge discharge time ? the charge discharge time field selects the amount of time an electrode charges and discharges. 000 encoding 0 ? invalid 001 encoding 1 ? time is set to 0.5 s 010 encoding 2 ? time is set to 1 s ~ 111 encoding 7 ? time is set to 32 s. 4:3 sfi second filter iterations ? the second filter iterations field selects the number of samples taken for the second level filter. 00 encoding 0 ? number of samples is set to 4 01 encoding 1 ? number of samples is set to 6 10 encoding 2 ? number of samples is set to 10 11 encoding 3 ? number of samples is set to 18 2:0 esi electrode sample interval ? the electrode sample interval field selects the period between samples used for the second level of filtering. 000 encoding 0 ? period set to 1 ms 001 encoding 1 ? period set to 2 ms ~ 111 encoding 7 ? period set to 128 ms 7 6 543210 r0 0 mhd w reset:0 0 000000 = unimplemented table 14. max half delta re gister field descriptions field description 5:0 mhd max half delta ? the max half delta determines the largest magnitude of variation to pass through the third level filter. 000000 do not use this code 000001 encoding 1 ? sets the max half delta to 1 ~ 111111 encoding 63 ? sets the max half delta to 63
mpr03x sensors 22 freescale semiconductor preliminary 8.4.2 noise half delta register the noise half delta register is used to set the noise half de lta for the third level filter. the address of the noise half del ta register is 0x27. figure 28. noise half delta register 8.4.3 noise count limit register the noise count limit register is used to set the noise count li mit for the third level filter. the address of the noise half d elta register is 0x28. figure 29. noise count limit register 7 6 543210 r0 0 nhd w reset:0 0 000000 = unimplemented table 15. noise half delta register field descriptions field description 5:0 nhd noise half delta ? the noise half delta determines the incremental change when non-noise drift is detected. 000000 do not use this code 000001 encoding 1 ? sets the noise half delta to 1 ~ 111111 encoding 63 ? sets the noise half delta to 63 7 6 543210 r0 0 0 0 ncl w reset:0 0 000000 = unimplemented table 16. noise count limit register field descriptions field description 3:0 ncl noise count limit ? the noise count limit dete rmines the number of samples consecutively greater than the max half delta necessary before it can be determined that it is non-noise. 0000 encoding 0 ? sets the noise count limit to 1 (every time over max half delta) 0001 encoding 1 ? sets the noise count limit to 2 consecutive samples over max half delta ~ 1111 encoding 15 ? sets the noise count limit to 15 consecutive samples over max half delta
mpr03x sensors freescale semiconductor 23 preliminary 9 touch detection 9.1 introduction the mpr03x uses a threshold based system to determine when touches occur. th is section will descr ibe that mechanism. 9.2 thresholds when a touch pad is pressed, an increase in capacitance will be generated. the resulting effect will be a reduction in the adc counts. when the difference between the second level filter value and the third level filter value is significant, the system w ill detect a touch. when a touch is detected, there are a couple of effects: the third level filter output becomes fixed (refer to section 8.4 ), an interrupt is generated (refer to section 6 ), and the touch status register ( section 5.2 ) is updated. the touch detection system is controlled using two threshold registers for ea ch independent electrode. the touch threshold register represents the delta at which t he system will trigger a touch. the release th reshold represents the difference at whic h a release would be detected. in either case the system will respond by changing the previously mentioned items. 9.2.1 touch threshold register the touch threshold register is used to set the touch threshold for each of the electrodes. the address of the ele0 touch threshold register is 0x29. the address of the ele1 touch th reshold register is 0x2a. the address of the ele2 touch threshold register is 0x2b. figure 30. touch threshold register 9.2.2 release threshold register the release threshold register is used to set the release thres hold for each of the electrodes. the address of the ele0 release threshold register is 0x2c. the address of the ele1 release th reshold register is 0x2d. the address of the ele2 release threshold register is 0x2e. figure 31. release threshold register 7 6 543210 r tth w reset:0 0 000000 = unimplemented table 17. touch threshold register field descriptions field description 7:0 tth touch threshold ? the touch threshold byte sets the trip point for detecting a touch. 00000000 encoding 0 ~ 11111111 encoding 255 7 6 543210 r rth w reset:0 0 000000 = unimplemented table 18. release threshold register field descriptions field description 7:0 rth release threshold ? the release threshold byte sets the trip point for detecting a touch. 00000000 encoding 0 ~ 11111111 encoding 255
mpr03x sensors 24 freescale semiconductor preliminary appendix a electrical characteristics a.1 introduction this section contains electric al and timing specifications. a.2 absolute maximum ratings absolute maximum ratings are stress ratings only, and functional ope ration at the maxima is not guaranteed. stress beyond the limits specified in ta b l e 1 9 may affect device reliability or cause perma nent damage to the device. for functional operating conditions, refer to the remaining tables in this section. this device contains circuitry protecting against damage due to high static voltage or electrical fields; however, it is advised that norma l precautions be taken to avoid application of any voltages high er than maximum-rated voltages to this high-impedance circuit. a.3 esd and latch-up prot ection characteristics normal handling precautions should be used to avoid exposure to static discharge. qualification tests are performed to ensure that these devices can withstand exposur e to reasonable levels of static without suffering any permanent damage. during the device qualificatio n esd stresses were performed for the human body model (hbm), the machine model (mm) and the charge device model (cdm). a device is defined as a failure if after exposure to esd pulse s the device no longer meets the device specification. complete dc parametric and functional testing is performed per the applicab le device specification at room temperature followed by hot temperature, unless specified other wise in the device specification. table 19. absolute maximum ratings - voltage (with respect to v ss ) rating symbol value unit supply voltage v dd -0.3 to +2.9 v input voltage scl, sda, irq v in v ss - 0.3 to v dd + 0.3 v operating temperature range tsg -40 to +85 c storage temperature range t sg -40 to +125 c table 20. esd and latch-up test conditions rating symbol value unit human body model (hbm) v esd 4000 v machine model (mm) v esd 200 v charge device model (cdm) v esd 500 v latch-up current at t a = 85c i latch 100 ma
mpr03x sensors freescale semiconductor 25 preliminary a.4 dc characteristics this section includes information about power supply requirements and i/o pin characteristics. 1. parameters tested 100% at final test at room temperature; limits at -40c and +85c verified by characterization, not tested in production 2. limits verified by characte rization, not tested in production a.5 ac characteristics 1. parameters tested 100% at final test at room temperature; limits at -40c and +70c verified by characterization, not tested in production 2. limits verified by characte rization, not tested in production. table 21. dc characteristics (temperature range = ?40c to 85c ambient) (typical operating circuit, v dd = 1.71 v to 2.75 v, t a = t min to t max , unless otherwise noted. typical current values are at v dd = 1.8 v, t a = +25c.) parameter symbol conditions min typ max units operating supply voltage v dd 1.71 1.8 2.75 v 1 average supply current i dd run1 mode @ 1 ms sample period 43 57.5 a 2 average supply current i dd run1 mode @ 2 ms sample period 22 32 a 2 average supply current i dd run1 mode @ 4 ms sample period 14 19.4 a 2 average supply current i dd run1 mode @ 8 ms sample period 8 13.3 a 2 average supply current i dd run1 mode @ 16 ms sample period 6 10.1 a 2 average supply current i dd run1 mode @ 32 ms sample period 58.6 a 2 average supply current i dd run1 mode @ 64 ms sample period 47.8 a 2 average supply current i dd run1 mode @ 128 ms sample period 47.5 a 2 measurement supply current i dd peak of measurement duty cycle 1.25 1.5 ma 2 idle supply current i dd stop mode 1.5 4 a 1 electrode charge current accuracy ele_ relative to nominal values programmed in register 0x41 -6 +6 % 1 electrode input working range ele_ electrode charge current accuracy within specification 0.7 v dd - 0.7 v 1 input leakage current ele_ i ih , i il 0.025 1 a 1 input capacitance ele_ 15 pf 2 input high voltage sda, scl v ih 0.7 x v dd v 2 input low voltage sda, scl v il 0.3 x v dd v 2 input leakage current sda, scl i ih , i il 0.025 1 a 2 input capacitance sda, scl 7pf 2 output low voltage sda, irq v ol i ol = 6ma 0.5v v 1 power on reset v tlh v dd rising 1.08 1.35 1.62 v 2 v thl v dd falling 0.88 1.15 1.42 v 2 table 22. ac characteristics (typical operating circuit, v dd = 1.71v to 2.75v, t a = t min to t max , unless otherwise noted. typical values are at v dd = 1.8v, t a = +25c.) parameter symbol conditions min typ max units 8 mhz internal oscillator f h 7.44 8 8.56 mhz 1 32 khz internal oscillator f l 20.8 32 43.2 khz 1
mpr03x sensors 26 freescale semiconductor preliminary a.6 i 2 c ac characteristics this section includes information about i 2 c ac characteristics. table 23. i 2 c ac characteristics (typical operating circuit, v dd = 1.71 v to 2.75 v, t a = t min to t max , unless otherwise noted. typical current values are at v dd = 1.8 v, t a = +25c.) parameter symbol conditions min typ max units serial clock frequency f scl 400 khz 1 bus free time between a stop and a start condition t buf 1.3 s 2 hold time, (repeated) start condition t hd, sta 0.6 s 2 repeated start condition setup time t su, sta 0.6 s 2 stop condition setup time t su, sto 0.6 s 2 data hold time t hd, dat 0.9 s 2 data setup time t su, dat 100 ns 2 scl clock low period t low 1.3 s 2 scl clock high period t high 0.7 s 2 rise time of both sda and scl signals, receiving t r 20+0.1 c b 300 ns 2 fall time of both sda and scl signals, receiving t f 20+0.1 c b 300 ns 2 fall time of sda transmitting t f.tx 20+0.1 c b 250 ns 2 pulse width of spike suppressed t sp 25 ns 2 capacitive load for each bus line c b 400 pf 2
mpr03x sensors freescale semiconductor 27 preliminary appendix b brief register descriptions register abrv fields register address initial value touch status register ts ocf e2s e1s e0s 0x00 0x00 ele0 filtered data low register e0fdl e0fdlb 0x02 0x00 ele0 filtered data high register e0fdh e0fdhb 0x03 0x00 ele1 filtered data low register e1fdl e1fdlb 0x04 0x00 ele1 filtered data high register e1fdh e1fdhb 0x05 0x00 ele2 filtered data low register e2fdl e2fdlb 0x06 0x00 ele2 filtered data high register d2fdh e2fdhb 0x07 0x00 ele0 baseline value register e0bv e0bv 0x1a 0x00 ele1 baseline value register e1bv e1bv 0x1b 0x00 ele2 baseline value register e2bv e2bv 0x1c 0x00 max half delta register mhd mhd 0x26 0x00 noise half delta register nhd nhd 0x27 0x00 noise count limit register ncl ncl 0x28 0x00 ele0 touch threshold register e0tth e0tth 0x29 0x00 ele0 release threshold register e0rth e0rth 0x2a 0x00 ele1 touch threshold register e1tth e1tth 0x2b 0x00 ele1 release threshold register e1rth e1rth 0x2c 0x00 ele2 touch threshold register e2tth e2tth 0x2d 0x00 ele2 release threshold register e2rth e2rth 0x2e 0x00 afe configuration register afec ffi cdc 0x41 0x08 filter configuration register fc cdt sfi esi 0x43 0x04 electrode configuration register ec call ock modesel eleen 0x44 0x00
mpr03x sensors 28 freescale semiconductor preliminary appendix c order ing information c.1 ordering information this section contains ordering information for mpr03x devices. c.2 device numbering scheme all proximity sensor products have a si milar numbering scheme. the below diagram ex plains what each part number in the family represents. ordering information device name temperature range case number touch pads i 2 c address shipping mpr031ep -40 c to +85 c 1944 (8-pin udfn) 3-pads 0x4a bulk mpr031epr2 -40 c to +85 c 1944 (8-pin udfn) 3-pads 0x4a tape and reel MPR032ep -40 c to +85 c 1944 (8-pin udfn) 3-pads 0x4b bulk MPR032epr2 -40 c to +85 c 1944 (8-pin udfn) 3-pads 0x4b tape and reel m status (m = fully qualified, p = preproduction) pr proximity sensor product ee x p number of electrodes (03 = 3 electrode device) package designator version (q = qfn, ej = tssop, ep = dfn)
mpr03x sensors freescale semiconductor 29 preliminary package dimensions page 1 of 3
mpr03x sensors 30 freescale semiconductor preliminary page 2 of 3
mpr03x sensors freescale semiconductor 31 preliminary page 3 of 3
mpr03x rev. 2.0 11/2008 how to reach us: home page: www.freescale.com web support: http://www.freescale.com/support usa/europe or locations not listed: freescale semiconductor, inc. technical information center, el516 2100 east elliot road tempe, arizona 85284 1-800-521-6274 or +1-480-768-2130 www.freescale.com/support europe, middle east, and africa: freescale halbleiter deutschland gmbh technical information center schatzbogen 7 81829 muenchen, germany +44 1296 380 456 (english) +46 8 52200080 (english) +49 89 92103 559 (german) +33 1 69 35 48 48 (french) www.freescale.com/support japan: freescale semiconductor japan ltd. headquarters arco tower 15f 1-8-1, shimo-meguro, meguro-ku, tokyo 153-0064 japan 0120 191014 or +81 3 5437 9125 support.japan@freescale.com asia/pacific: freescale semiconductor china ltd. exchange building 23f no. 118 jianguo road chaoyang district beijing 100022 china +86 010 5879 8000 support.asia@freescale.com for literature requests only: freescale semiconductor lite rature distribution center p.o. box 5405 denver, colorado 80217 1-800-441-2447 or +1-303-675-2140 fax: +1-303-675-2150 ldcforfreescalesemiconductor@hibbertgroup.com information in this document is provided solely to enable system and software implementers to use freescale semiconduc tor products. there are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document. freescale semiconductor reserves the right to make changes without further notice to any products herein. freescale semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does freescale semiconductor assume any liability ar ising out of the application or use of any product or circuit, and specifically discl aims any and all liability, including without limitation consequential or incidental damages. ?typical? parameters that may be provided in freescale semiconductor data s heets and/or specifications can and do vary in different applications and actual performance may vary over time. all operating parameters, including ?typicals?, must be validated for each customer application by customer?s technical experts. freescale se miconductor does not convey any license under its patent rights nor the rights of others. freescale semiconductor products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the fa ilure of the freescale semiconductor product could create a situation where personal injury or death may occur. should buyer purchase or use freescale semiconductor products for any such unintended or unauthorized application, buyer shall indemni fy and hold freescale semiconductor and its officers, employees, subsidiaries, affili ates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that freescale semiconductor was negligent regarding the design or manufacture of the part. freescale? and the freescale logo are trademarks of freescale semiconductor, inc. all other product or service names are the property of their respective owners. ? freescale semiconductor, inc. 2008. all rights reserved. rohs-compliant and/or pb-free versions of freesc ale products have the functi onality and electrical characteristics of their non-rohs-compliant and/or non-pb-free counterparts. for further information, see http:/www.freescale.com or contact your freescale sales representative. for information on freescale?s environmental products program, go to http://www.freescale.com/epp.

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