Re: [R-engine-developers] After 2 nights of testing

[Peter M. <pe...@mc...>]

Two nights is nothing to get frustrated over! You're doing a fine
Stirling job! The problem here is that there are 256! or 32! possible
combinations for which GPIO pins do what. They are called General
Purpose because hardware designers are free to use any pin for anything
and quite often they select a pin because it makes the PCB layout easier
not be cause it makes logical pin sense.

Cheers,
Peter.

On Wed, 2005-08-17 at 23:23 +0200, Cedric Cellier wrote:
> Hello the list !
> 
> After 2 nights playing with the GPIO I am disapointed now.
> First, When you set all pins to inputs and read GPIOREAD, you got 
> '0xBB'. That is all ones but 2 bits. Ive read on V4Lwiki, and it seams 
> reasonnable, that the 1 bits are good candidates for outputs.
> 
> I then tryed all combinations involving thoses 6 bits for SDA and SCL, 
> trying to address chip address 0x42 (more probable address of a SAA7114, 
> considering the SAA7113 was addressed on it's default address too).
> 
> None of these combinations give me an ACK after the address was written.
> 
> So, I reversed my reasoning and try bits 0x4 and 0x40 alone for SDA and 
> SCL. This, neither, does not give ACK... except if you clear the bit 6 
> in what I call the 'Magick 0xC8FFFFCF', that is the 'end of reset' in 
> the mb86393_reset function that's called first.
> 
> I don't know where the 'CF' goes, but as its related to the GPIO I 
> played with it a bit. The only thing I am certain of, is that if you use 
> 0x40 for SDA and if you clear bit 0xb0 of this 0xc8ffffcf, then you will 
> have all the ack you want when reading the sda (?) line.
> 
> After two nights, this result is a bit frustrating. :-(
> 
> 
> 
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Peter McNeil
http://www.mcneils.net