XPT2046 Touch Controller

[KansaiRobot]

Hello
I am trying to control a XPT2046 touch controller.
I have programmed it but it does not work.
I have come to the conclusion that the SPI part might be the culprit.

My first question would be at what speed do I have to set the SPI clock???

Thanks a lot for any advice or comment

[PCM programmer]

Post a link to the data sheet for the XPT2046 touch controller.

[KansaiRobot]

Thanks for the reply

the datasheet is at

http://www.waveshare.com/w/upload/9/98/XPT2046-EN.pdf

[PCM programmer]

[Ttelmah]

Other obvious things are:

1) Remember Din on the chip = SDO on the PIC. Dout = SDI. It is very common to forget this swapping.
2) SPI mode number.
Looking at it the clock idles low. So CPOL=0, and data changes on the falling edge, so CPHA=0. SPI mode 1.

#USE SPI (SPI1, MODE=1, BAUD=2500000, STREAM=XPT)

Assuming you are using hardware SPI 1.

Drop CS - output_low(CS_PIN);
Clock out the 8bit command - spi_xfer(XPT, command,8);
Wait for 'BUSY' to go low. - while(INPUT(BUSY_PIN);
Read the 16bit reply - reply=spi_xfer(XPT,0,16);
Raise CS - output_high(CS_PIN);

Then reply/=16.

Obviously with suitable defined values for CS_PIN, BUSY_PIN, and value for 'command', and an int16 variable for 'reply'.

[KansaiRobot]

I have written a program and I would appreciate some help
but it is written in XC compiler for PICs. Can I post it here??

[PCM programmer]

No, this is the CCS compiler forum. If you're using XC8, then post your
questions in one of the Microchip forums:
http://www.microchip.com/forums/Forums

[KansaiRobot]

I see. Thank you for the indication.

Your explanation of the Frequency was very useful too. Very much grateful for that too