Master/slave control of touch sensing

Abstract

Touch sensing can be accomplished using master/slave touch controllers that transmit drive signals to a touch surface and process sense signals including superpositions resulting from master/slave drive signals. The master/slave can drive and sense different sets of lines, respectively, of the touch surface. A communication link between master/slave can be established by transmitting a clock signal between master/slave, transmitting a command including sequence information to the slave, and initiating a communication sequence from the clock signal and sequence information. The slave can receive/transmit communications from/to the master during first/second portions of the communication sequence, respectively. Touch sensing operations can be synchronized between master/slave by transmitting a command including phase alignment information from master to slave, and generating slave clock signals based on the clock signal and the phase alignment information, such that sense signal processing by master clock signals are in-phase with sense signal processing by slave clock signals.

What is claimed is: 
     
         1 . A system comprising:
 master touch controller circuitry; and   slave touch controller circuitry coupled to the master touch controller circuitry;   wherein the master touch controller circuitry and slave touch controller circuitry are configured to stimulate sensing nodes of a touch sensitive surface at least partially simultaneously with a plurality of stimulation signals, wherein the plurality of stimulation signals include at least a first stimulation signal from the master touch controller circuitry and at least a second stimulation signal from the slave touch controller circuitry; and   wherein the slave controller circuitry is configured to sense one or more first sense signals from the sensing nodes of the touch sensitive surface, the one or more first sense signals affected by the first stimulation signal from the master touch controller circuitry and the second stimulation signal from the slave touch controller circuitry.   
     
     
         2 . The system of  claim 1 , wherein the master touch controller circuitry is configured to sense one or more second sense signals from the sensing nodes of the touch sensitive surface, the one or more second sense signals affected by the first stimulation signal from the master touch controller circuitry and the second stimulation signal from the slave touch controller circuitry. 
     
     
         3 . The system of  claim 2 , wherein the master touch controller circuitry is configured to transmit a first clock signal and a set clock command to the slave touch controller circuitry. 
     
     
         4 . The system of  claim 3 , wherein the master touch controller circuitry is configured to establish a serial communication between the master touch controller circuitry and the slave touch controller circuitry before transmitting the set clock command. 
     
     
         5 . The system of  claim 4 , wherein the communication between the master touch controller circuitry and slave touch controller circuitry includes alternating periods of transmission of the master touch controller circuitry and the slave touch controller circuitry. 
     
     
         6 . The system of  claim 5 , wherein the communication between the master touch controller circuitry and slave touch controller circuitry includes transmission of a second command that causes two consecutive periods of transmission for one of the master touch controller circuitry and the slave touch controller circuitry. 
     
     
         7 . The system of  claim 3 , wherein the slave touch controller circuitry is configured to generate, in response to the set clock command and based on the first clock signal, a plurality of slave clock signals, wherein the plurality of slave clock signals are generated in a known phase relationship with one or more master clock signals of the master touch controller circuitry wherein at least one of the plurality of slave clock signals is at a different frequency than the first clock signal. 
     
     
         8 . The system of  claim 7 , wherein the first stimulation signal from the master touch controller circuitry is generated based on the master clock signal, and the second stimulation signal from the slave touch controller circuitry is generated using one of the plurality of slave clock signals. 
     
     
         9 . The system of  claim 7 , wherein the master touch controller circuitry and slave touch controller circuitry are configured to demodulate the one or more first sense signals and the one or more second sense signals with in-phase demodulation signals based on the phase relationship of the plurality of slave clock signals and the one or more master clock signals. 
     
     
         10 . The system of  claim 7 , wherein the master touch controller circuitry includes a first decimation filter and the slave touch controller circuitry includes a second decimation filter operating on the one or more first sense signals and the one or more second sense signals, wherein the first decimation filter and the second decimation filter operate in-phase with each other based on the phase relationship of the plurality of slave clocks signals and the one or more master clock signals. 
     
     
         11 . A method comprising:
 stimulating sensing nodes of a touch sensitive surface at least partially simultaneously with a plurality of stimulation signals, wherein the plurality of stimulation signals include at least a first stimulation signal from master touch controller circuitry and at least a second stimulation signal from slave touch controller circuitry; and   sensing one or more sense signals from the sensing nodes of the touch sensitive surface, the one or more sense signals affected by the first stimulation signal from the master touch controller circuitry and the second stimulation signal from the slave touch controller circuitry.   
     
     
         12 . The method of  claim 11 , further comprising:
 transmitting a first clock signal from the master touch controller circuitry to the slave touch controller circuitry;   transmitting a first command from the master touch controller circuitry to the slave touch controller circuitry; and   generating, by the slave touch controller circuitry in response to the first command and based on the first clock signal, a plurality of slave clock signals in the slave touch controller circuitry, at least one of the plurality of slave clock signals different from the first clock signal, wherein the plurality of slave clock signals are generated in a known phase relationship with one or more master clock signals of the master touch controller circuitry.   
     
     
         13 . The method of  claim 12 , further comprising:
 establishing a serial communication link between the master touch controller circuitry and the slave touch controller circuitry before transmitting the first command.   
     
     
         14 . The method of  claim 12 , further comprising:
 transmitting a second command from the master touch controller circuitry to the slave touch controller circuitry; and   in response to the second command, causing two consecutive periods of transmission for the master touch controller circuitry or the slave touch controller circuitry.   
     
     
         15 . The method of  claim 12 , further comprising:
 demodulating the one or more sense signals with in-phase demodulation signals based on the phase relationship of the plurality of slave clock signals and the one or more master clock signals.   
     
     
         16 . A non-transitory computer readable storage medium storing instructions, which when executed by touch controller circuitry, cause the touch controller circuitry to perform a method, the method comprising:
 stimulating sensing nodes of a touch sensitive surface at least partially simultaneously with a plurality of stimulation signals, wherein the plurality of stimulation signals include at least a first stimulation signal from master touch controller circuitry and at least a second stimulation signal from slave touch controller circuitry; and   sensing one or more sense signals from the sensing nodes of the touch sensitive surface, the one or more sense signals affected by the first stimulation signal from the master touch controller circuitry and the second stimulation signal from the slave touch controller circuitry.   
     
     
         17 . The non-transitory computer readable storage medium of  claim 16 , the method further comprising:
 transmitting a first clock signal from the master touch controller circuitry to the slave touch controller circuitry;   transmitting a first command from the master touch controller circuitry to the slave touch controller circuitry; and   generating, by the slave touch controller circuitry in response to the first command and based on the first clock signal, a plurality of slave clock signals in the slave touch controller circuitry, at least one of the plurality of slave clock signals different from the first clock signal, wherein the plurality of slave clock signals are generated in a known phase relationship with one or more master clock signals of the master touch controller circuitry.   
     
     
         18 . The non-transitory computer readable storage medium of  claim 17 , the method further comprising:
 establishing a serial communication link between the master touch controller circuitry and the slave touch controller circuitry before transmitting the first command.   
     
     
         19 . The non-transitory computer readable storage medium of  claim 17 , the method further comprising:
 transmitting a second command from the master touch controller circuitry to the slave touch controller circuitry; and   in response to the second command, causing two consecutive periods of transmission for the master touch controller circuitry or the slave touch controller circuitry.   
     
     
         20 . The non-transitory computer readable storage medium of  claim 17 , the method further comprising:
 demodulating the one or more sense signals with in-phase demodulation signals based on the phase relationship of the plurality of slave clock signals and the one or more master clock signals.