Snr - aware active mode touch scans

Abstract

A touch controller can dynamically balance performance criteria, such as signal-to-noise ratio (SNR) thresholds, with power consumption for touch sensitive devices. A touch controller can be configured to reduce power consumption by reconfiguring bank boundaries for an active mode scan so as to reduce the number of banks scanned with a banked active mode scan. Additionally or alternatively, the stimulation signal amplitude and integration time of the touch controller can be dynamically adjusted to balance performance criteria with power consumption. Default integration times and default stimulation signal amplitudes can be increased in higher-noise operating environments to raise SNR, and can be reduced to save power in lower-noise operating environments. Additionally or alternatively, the touch scanning rate of the touch controller can be dynamically adjusted to reduce power consumption of the touch sensitive device or to reallocate touch sensing frames to increase integration times and thereby SNR performance.

What is claimed is: 
     
         1 . An electronic device comprising:
 a touch-sensitive surface; and   one or more processors coupled to the touch-sensitive surface and configured to:
 detect one or more conditions of the electronic device; 
 in accordance with a determination that one or more performance requirements are satisfied under the one or more conditions, perform touch scanning at a first touch scanning rate; and 
 in accordance with a determination that the one or more performance requirements are not satisfied, perform the touch scanning at a second touch scanning rate, greater than the first touch scanning rate. 
   
     
     
         2 . The electronic device of  claim 1 , wherein detecting the one or more conditions comprises determining a number of objects proximate to the touch-sensitive device, and wherein the one or more performance requirements include a performance requirement that is satisfied when the number of objects proximate to the touch-sensitive device is two or greater. 
     
     
         3 . The electronic device of  claim 1 , wherein detecting the one or more conditions comprises detecting a peripheral device communicatively coupled to the touch-sensitive device, and wherein the one or more performance requirements include a performance requirement that is satisfied while the peripheral device is detected. 
     
     
         4 . The electronic device of  claim 1 , further comprising:
 in accordance with the determination that the one or more performance requirements are satisfied under the one or more conditions, performing touch scanning with stimulation signals having a first stimulation signal amplitude and a first integration time; and   in accordance with the determination that the one or more performance requirements are not satisfied, performing touch scanning with stimulation signals having a second stimulation signal amplitude and a second integration time, wherein the second stimulation signal amplitude is greater than the first stimulation signal amplitude or the second integration time is greater than the first integration time.   
     
     
         5 . The electronic device of  claim 1 , wherein detecting the one or more conditions comprises detecting one or more noise levels, and determining whether the one or more performance requirements are satisfied under the one or more conditions comprises determine a signal to noise ratio at the second touch scanning rate. 
     
     
         6 . The electronic device of  claim 1 , wherein detecting the one or more conditions comprises detecting a peripheral device communicatively coupled to the touch-sensitive device, and determining whether the one or more performance requirements are satisfied under the one or more conditions comprises determine a signal to noise ratio at the second touch scanning rate for touch scans and for scans for the peripheral device. 
     
     
         7 . The electronic device of  claim 1 , wherein performing the touch scanning at the first touch scanning rate comprises dropping one or more scans to save power. 
     
     
         8 . The electronic device of  claim 1 , wherein performing the touch scanning at the first touch scanning rate comprises reallocating scanning time to increase an integration time of a touch scan or a scan for a peripheral device. 
     
     
         9 . The electronic device of  claim 1 , wherein the one or more performance requirements include a performance requirement that is satisfied when a threshold signal to noise ratio for is met for touch signals. 
     
     
         10 . A method for adjusting a touch scanning rate of a touch-sensitive device comprising:
 detecting one or more conditions of the touch-sensitive device;   in accordance with a determination that one or more performance requirements are satisfied under the one or more conditions, performing touch scanning at a first touch scanning rate; and   in accordance with a determination that the one or more performance requirements are not satisfied, performing the touch scanning at a second touch scanning rate, greater than the first touch scanning rate.   
     
     
         11 . The method of  claim 10 , wherein detecting the one or more conditions comprises determining a number of objects proximate to the touch-sensitive device, and wherein the one or more performance requirements include a performance requirement that is satisfied when the number of objects proximate to the touch-sensitive device is two or greater. 
     
     
         12 . The method of  claim 10 , wherein detecting the one or more conditions comprises detecting a peripheral device communicatively coupled to the touch-sensitive device, and wherein the one or more performance requirements include a performance requirement that is satisfied while the peripheral device is detected. 
     
     
         13 . The method of  claim 10 , further comprising:
 in accordance with the determination that the one or more performance requirements are satisfied under the one or more conditions, performing touch scanning with stimulation signals having a first stimulation signal amplitude and a first integration time; and   in accordance with the determination that the one or more performance requirements are not satisfied, performing touch scanning with stimulation signals having a second stimulation signal amplitude and a second integration time, wherein the second stimulation signal amplitude is greater than the first stimulation signal amplitude or the second integration time is greater than the first integration time.   
     
     
         14 . The method of  claim 10 , wherein detecting the one or more conditions comprises detecting one or more noise levels, and determining whether the one or more performance requirements are satisfied under the one or more conditions comprises determine a signal to noise ratio at the second touch scanning rate. 
     
     
         15 . The method of  claim 10 , wherein detecting the one or more conditions comprises detecting a peripheral device communicatively coupled to the touch-sensitive device, and determining whether the one or more performance requirements are satisfied under the one or more conditions comprises determine a signal to noise ratio at the second touch scanning rate for touch scans and for scans for the peripheral device. 
     
     
         16 . The method of  claim 10 , wherein performing the touch scanning at the first touch scanning rate comprises dropping one or more scans to save power. 
     
     
         17 . The method of  claim 10 , wherein performing the touch scanning at the first touch scanning rate comprises reallocating scanning time to increase an integration time of a touch scan or a scan for a peripheral device. 
     
     
         18 . The method of  claim 10 , wherein performing the touch scanning at the first touch scanning rate comprises reallocating scanning time to increase an integration time only while detecting no objects proximate to the touch-sensitive device. 
     
     
         19 . The method of  claim 10 , wherein the one or more performance requirements include a performance requirement that is satisfied when a threshold signal to noise ratio for is met for touch signals. 
     
     
         20 . A non-transitory computer readable storage medium storing instructions, which when executed by an electronic device including a touch-sensitive surface and one or more processors, cause the one or more processors to perform a method, the method comprising:
 detecting one or more conditions of the electronic device;   in accordance with a determination that one or more performance requirements are satisfied under the one or more conditions, performing touch scanning at a first touch scanning rate; and   in accordance with a determination that the one or more performance requirements are not satisfied, performing the touch scanning at a second touch scanning rate, greater than the first touch scanning rate.