Check for power supply problems. Although unlikely, you could be
running your power supply on the edge - problems wouldn't appear on the
32Mb version, but the 64Mb version with slightly higher power
requirements could just push you over the edge.
Otherwise, there shouldn't be any differences between the 64/32 mib
versions with regard to SPI connected devices.
One question though: You have written a kernel driver to talk to the the
SPI display device right? This idea that writing to hardware using
user-mode code is completely brain-dead - you have no control over
timing problems, interrupts, or for that matter any access to the
features that the linux kernel provides you for device driver management.
-Brett
jeremfg wrote:
> Hi!
>
> We are currently trying to use the serial Digilent PmodCLS LCD with the SPI
> bus on a TS-7400 64mb version. The PmodCLS is a serial LCD including it's own
> microchip, so we only need to send ASCII characters on the SPI bus, and
> everything else is handled by the LCD.
>
> PmodCLS ->
> http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,401,473&Prod=PMOD-CLS
>
> Currently, it's working really fine with the 32mb version of the card, we can
> write on the CPU's registers of the SPI bus, and everything shows up fine on
> the LCD...
>
> However, as soon as we move to the 64mb version of the card, there is some
> messup... Even though the card seems indentical, same CPU and everything else
> seems identical except for the extra memory chip, it doesn't work well...
>
> I can assure you that the issue is hardware related... We've also tryed using
> the same SD card with the exact same OS on the 32-bit and 64-bit version...
>
> half the times, it simply does nothing on the LCD, the other half is splitted
> in two... some time writing the last character of the string I was sending,
> or in the second case, the last character of the last attempt followed by
> the first character of the current attempt....
>
> Never more than two characters, and it seems really slow in execution,
> compared to the 32mb version. Looking on an oscilloscope, we can clearly see
> that the LCD obey what it is sent... Only one, two or zero characters are
> sent, electrically, to the LCD so it isn't the issue!
>
> So, Is there any difference at all between the 32Mb version and the 64Mb
> version that isn't visible to the naked eye?
>
> Or does anyone have an hypothesis on what the problem could be?
>
> All I know, is that I base my C code on the temp_sensor example, and followed
> the documentation of the CPU thoroughly for initialisation and operation
>
> Any help would be greatly welcome!
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
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