Re: [hatari-devel] falcon crossbar and ff8932

[Laurent Sallafranque <laurent.sallafranque@xxxxxxx>]

Hi,

When I coded the crossbar, I used another file that describes the registers.
I haven't got any official doc for this, I did it by guessing the 
behaviour and with the help of the hardware.txt file.
I don't ever think I had a Falcon by the time.

I don't think it is possible to disconnect completly the sound from the 
crossbar, I'll have to check this with my Falcon.

If you look at the compendium, it gives another mapping for this 
register (which seems to be wrong anyway).

I'll do some tests.

Laurent






Le 21/09/2016 à 00:40, Nicolas Pomarède a écrit :
> Hi
>
> in falcon/crossbar.c, I see the destination device connections are 
> tested using bits 13-13 in ff8932 :
>
>         Source: D/A Convertor                 BIT 15 14 13 12
>         00 - DMA output ------------------------------+--+
>         01 - DSP output ------------------------------+--+
>         10 - External input --------------------------+--+
>         11 - ADC input -------------------------------+--'
>
> But on the doc here 
> http://www.atari-wiki.com/index.php/Atari_ST/STe/MSTe/TT/F030_Hardware_Register_Listing 
> they have :
>
>        |     |Destination: D/A Convertor            BIT 15 14 13 12|
>        |     |1 - Connect, 0 - Disconnect ---------------'  |  | ||
>        |     |00 - Source DMA-PLAYBACK ---------------------+--+ ||
>        |     |01 - Source DSP-XMIT -------------------------+--+ ||
>        |     |10 - Source External Input -------------------+--+ ||
>        |     |11 - Source A/D Convertor --------------------+--' ||
>        |     |0 - Handshake on, 1 - Handshake off ----------------'|
>
> This would mean by setting bit 15, all sources would be disconnected 
> from the D/A destination.
>
> With current code in Hatari, it seems bit 15 is never tested, so that 
> would mean something is always connected to the D/A destination.
>
> Is that really how it works on real Falcon ? It's not possible to have 
> nothing connected to the DAC destination ?
>
> If we want to connect dma playback to DAC for example, should we write 
> 0xxx (bit 15=0) to ff8932 or 8xxx (bit 15=1) ?
>
>
> Laurent, as you wrote code for the crossbar.c, do you have some 
> official Atari documentation or some pointers to some articles that 
> would explain this ?
>
> (other possibility would be to look how tos 4 works when we call the 
> system function to connect source/dest in crossbar)
>
> Nicolas