[hatari-devel] No sound in the Pacemaker Demo

[David Savinkoff <dsavnkff@xxxxxxxxx>]

----- Nicolas Pomarède wrote:
> Le 29/05/2014 20:00, Jerome Vernet a écrit :
> > On 29/05/14 16:28, Eero Tamminen wrote:
> 
> >
> > Still no sound in the Pacemaker Demo.
> >
> 
> It seems  there's a problem when microwire mixer is set.
> 
> Demo set mask to 0xc1ff and data to 0x8000, which should decode as 
> command 10 000 000000 and set mixer=0.
> 
> But as it was tested lately on real STE (see 
> http://www.atari-forum.com/viewtopic.php?f=3&t=26360&start=250#p252373
> , mixer=0 doesn't give any sound. So, this was recently modified in Hatari.
> 
> But this demo use a non standard mask of 0xc1ff instead of 0x7ff, maybe 
> in that case the microwire ignores the command and we should keep the 
> value set by TOS, which is mixer=1.

I believe you are correct ( 0xc1ff erroneously contravenes specifications).

> 
> I need to check that in the microwire doc.
> 
> Nicolas
> 

I looked at the LMC1992 data sheet, here is what I surmise:

1) The mask must be at least eleven consecutive bits long, or the
   LMC1992 is left in an intermediate state, and restarts the sequence
   when there is a break in the mask. Think of the Mask as an enable
   signal.
   (Six usable 11 bit Masks. eg. 0011111111111000, 0000011111111111)
   (Five usable 12 bit Masks)
   (Zero usable Masks less than 11 bits long)

   Note that it may be possible to send two (or more) 16 bit Masks that
   act as a single 32 bit Mask.
   ( 0000000000011111, 1111110000000000 )

2) The first two Mask bits are a device address. The last nine bits
   are register bits. Any bits between the first two and last nine are
   lost when the Mask is longer than eleven bits.