WEC7 project (Platform Builder): touch screen display drivers issue

Question

I am trying to create a WEC7 image with Platform Builder, starting from an example workspace (from Variscite AM33 Ev. kit). I would like to connect a capacitive tousch screen display (Ampire AM-800480SBTMQW-T00): the touch screen does not work, perhaps the touch drivers included in the workspace are not compatible with my display ones. In the display datasheet there is a piece of source code: where should I have to add it in order to have the touch screen working? Is there a C source file, or maybe a registry that I should modify?

Answer 1

The Ampire panel is different from the one originally fitted on the Variscite board, so you will need to modify the touch PDD, i.e. the hardware-specific parts of the touch driver.

I am not familiar with the Variscite BSP, but a good place to look for the PDD would be in C:\WINCE700\PLATFORM\<BSP>\SRC\DRIVERS\TOUCH. For example, in the sample EVM3530 BSP the touch PDD is located in C:\WINCE700\PLATFORM\ti_evm_3530\SRC\DRIVERS\TOUCH. Generally, you are looking for the implementation of the functions documented here.

Without going into all the details, the way the touch PDD is supposed to work is that Windows CE (or, rather, the touch MDD) calls TchPdd_Init (your code in the PDD), passing a TCH_MDD_INTERFACE_INFO struct. This struct contains a pointer to a callback function in the MDD (pfnMddReportSampleSet), which the PDD can use to report touch events.

The PDD then typically sets up a thread to handle interrupts from the touch controller, read updated touch information from the hardware, and notify the MDD using the callback.