Re: Touchscreen chip is not an ADS 7846

Hello Pierre,

Tuesday, January 30, 2007, 12:06:54 AM, you wrote:

> Paul Sokolovsky a ecrit :
>> Hello Pierre,
>>
>> Monday, January 29, 2007, 9:26:04 PM, you wrote:
>>
>> []
>>
>>>> Yes, I refactored it exactly for your use, and I'd appreciate if you
>>>> give it try (and win ;-) ). Please see h4000 code fro how to use it
>>>> (pretty simple actually, you just need to pass in pen down IRQ).
>>>>
>>>> I also confirmed that ADS7846 and TSC2046 are exact clones. Quoting
>>>> doc:
>>>> "The TSC2046 is 100% pin-compatible with the existing
>>>> ADS7846, and will drop into the same socket."
>>>> They talk about pin compatibility here, but looking at command bits,
>>>> programmatical interface is the same too. So, this is great news,
>>>> meaning that the whole dozen of PDAs can use the same driver. I will
>>>> try ads7846ts_ssp on hx4700 as the next thing to do too.
>>>>
>>>>
>>> ok : go for it, then :-)
>>> Just a question : do you have any idea of the transfer laws to be used ?
>>> I get some really non-linear measurements...
>>>
> Something goes wrong with the device-independent 7846 driver.
> It seems that the SPI communication is faulty. As long as the stylus is
> down, it prints :

> ads7846_ssp_putget: warning: timeout while waiting for SSSR_RNE_MSK
> ads7846_ssp_putget: warning: timeout while waiting for SSSR_TNF_MSK
> ads7846_ssp_putget: warning: timeout while waiting for SSSR_RNE_MSK
> ads7846_ssp_putget: warning: timeout while waiting for SSSR_TNF_MSK

> I do not understand why...
> Attached is the touchscreen module I hacked, if it can help.

  Well, I actually also reviewed the ads7846ts_ssp vs hx4700_ts code,
preparing to use the first in place of second, and discovered few
things and fixed few issues. First of all, PXA25x and PXA27x appear to
have differences in SSP ports. PXA27x has few more features and
different base SSP frequency. But even with that, ads7846_ssp should
still work on PXA27x (the frequency it uses is still lower than used
on hx4700_ts and offshots). Of course, as long as SSP1 port is used,
and that appears to be your case. At the same time, I fixes some race
condition in ads7846_ssp. So, please try it now, and if it still won't
work, then oops, I'll need to make it run on hx4700 first then.

> Pierre

-- 
Best regards,
 Paul                            mailto:pmiscml_at_gmail.com