Problem of TouchScreen

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originally posted by jimyh@Jun 27 2006, 10:29 AM

i added a touchscreen to my system and found some problems.

the touch screen controller is ads7843. i want to use a spi core inside nios ii to access the controller, but, failed. i found the timing graph for ads7843 is not match with the spi master core in nios ii.

i use pio to simulate the spi protocal which ads7843 needed, and everything is fine. the result is the code size and bad performance.

did anyone do this before?

and in ads7843, the master must read data from it 2 times without cs signal go high. but in nios's spi, if the data width is setted, 2 times data read will occur the event that cs signal back to high and go low again. how to solve it? add a dedicated cs signal from pio and controll it?

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There is a SPI master/slave IP core on the opencores web site. Maybe it would help, but I think you will have to create an avalon interface before using it in SOPC.

You will find the project here :

http://www.opencores.org/projects.cgi/web/spi/overview (http://www.opencores.org/projects.cgi/web/spi/overview)

Regards.