CapSense wake up on finger touch

Question: Can I make a design in a such a way that the CapSense PSoC wakes up from sleep when the finger touch us detected

 

Answer:


PSoC CapSense uses the technique of continuous scanning (polling) the sliders and buttons for detecting finger touch. Therefore PSoC has to be awake to receive inputs from sliders or buttons and it is not possible generate an interrupt that can return PSoC from sleep mode. However the device can use the sleep timer to return from sleep mode. Following method can be used to reduce the current consumption:

Wake up from sleep on sleep timer interrupt >> scan the capsense sensors >> go to sleep again

To reduce the power consumption even further, instead of all the sensors, only one proximity sensor can be scanned such that the active time (time required to scan all sensors) is reduced. Note that the proximity sensor need not be an extra sensor on the layout, various buttons can be ganged together to form the proximity sensor as well.
 

Related resources:

1. Code examples

2. Power consumption calculation

3. Getting started with CapSense design guide