Avoiding Cross-talk

In ATMEL QTouch library variants that use QTouch acquisition technology, adjacent sensors are not measured at the same time. This prevents interference due to cross-talk between adjacent channels, but at the same time some sensor configurations take longer to measure than others.

For example, if an 8-channel device is configured to support 8 keys, then the library will measure the keys on channels 0, 2, 4, and 6 parallely, followed by keys on channels 1, 3, 5, and 7. If the same device is configured, say, to support 4 keys, putting them either on all the odd channels or on all the even channels means that they can all be measured simultaneously.

This means the library calls are faster, and the device can use less power. So, it is recommended that the appropriate channel numbers are used when using less than the maximum number of channels available for the device to ensure optimum performance. In a similar sense for faster execution and reduced power consumption, it is also advisable to use intra-port sensor configuration instead of inter-port sensor configuration while using 4 channels on the same port.