Example for ATSAM

Table 1. The example below will explain in detail the steps to follow for library selection
Criteria	Selection		Notes
Microcontroller	AT91SAM3S
IDE and compiler tool chain used	IAR Workbench and GNU compiler		The GCC compiled variant of the libraries for the device selected needs to be used.
Number of Keys required for the application	3		Each key requires 1 QTouch acquisition channel
Rotors and sliders required	Yes
Number of Rotors and Sliders required	3		Each rotor / slider will require 3 channels.
Number of Channels required for the application ( should be the sum of all channels required for all the keys ,rotors and sliders used in the design )	12		3 Keys + ( 3 rotors x 3 channels per rotor/slider )  12 channels
Charge cycle time required for the design	5 cycles		Assuming the device is configured with a clock frequency of 48Mhz
Number of SNS/SNSK port pairs needed	2 pairs		This is determined based on the free PIO of the board
Choice of ports available for the design	SNS/ SNSK Pair1 ports	SNS1 Port : A
	SNS/ SNSK Pair1 ports	SNSK1 Port : A
	SNS/ SNSK Pair 2 ports	SNS2 Port : B
	SNS/ SNSK Pair 2 ports	SNSK2 Port : B

Given the above requirements for the applications, the first step is to select the right library variant required.

Step 1: Selecting the right library variant

Referring to the library selection guide, we see that there are a few variants of libraries supported for AT91SAM3S. One library is for IAR and the other is for GNU. If we want to use IAR Workbench, we use the library name: libsam3s-32qt-k-8rs-iar.a.

Step 2: Defining the constants / symbols in the project space

In IAR, change preprocessor options by adding the good defines:

_TOUCH_ARM_
_QTOUCH_
SNS1=B
SNSK1=B
SNS2=A
SNSK2=A
QT_NUM_CHANNELS=32
_ROTOR_SLIDER_
QT_DELAY_CYCLES=10
_SNS1_SNSK1_SAME_PORT_
_SNS2_SNSK2_SAME_PORT_

Step3: Usage of library API’s

Now, you can use the touch API’s to create, initialize and perform touch sensing.