TOuch Screen COntroller ADS 7846

[keila]

ads7846

Hai!

I'm working on developing a touch panel interface to a graphic display.
The resolution of touch panel is 255*255.
THe touch screen controller i'm using is ADS 7846 which works on SPI.
The host controller is AT89c51RD2.
I had written a C code for calculation of the position of touch on touch panel.
The o/p i get is the coordinates in hexadecimal format.
Now coming to the problem,

I'm getting coordinates only in the range fron (00 to 1F), but not from (00 to FF).
So any one could help me in software?
Or anyone who can give me a better code?

Thanks in Advance.

 

[M!k]

7846 touch

Please check the datasheet of ADS7846: it's resolution is 12 bit (0x00 - 0x0FFF)
So perhaps you've got a problem with the representation of the bits or with the reception via SPI. A good way to check this is to you use a DSO at the SPI.

 

[keila]

ads7846 code

Tq for ur reply.

But 7846 is not limited to 12 bit resolution we can have 8 bit resolution also and it is programmed via the control byte needed for coordinates generation by the A/D.

There is a "MODE" bit in the control byte, with which we can select either 12 bit resolution or 8 bit resolution, and I took 8-bit resolution.

My doubt is, if we checked for 8 bit resolution, do I get the XY coordinates in the range from (0 to 255) or from (0 to 4096)?

 

[electronicart]

programming spi ads7846

can u tell me what mode and speed of SPI u have used to interface with ads7846
i am also usign ARM LPC2129 to interface with it but i am very confuse which mode should be used
can u help me