AOUT-LC questions

[jjonas]

Hi,

I've built an MBSID with a single SID chip in it, and I'd like to add an SSM2044 filter to it. So I need two channels: one for cutoff, one for resonance.

In the MBSID sources (setup_8580.asm) there's the choice between three different resolution options:

    ;; only relevant if one or more AOUT_LC modules are used:
    ;; define the resolution configuration here
    ;;   0: first channel 12bit, second channel 4bit
    ;;   1: first channel 8bit, second channel 8bit
    ;;   2: combines M1,M2 and/or M3/M4: first channel 12bit, second channel 12bit, third channel 8bit, fourth channel ignored!
    ;; all other values invalid!
#define AOUT_LC_RESOLUTION_OPTION_M1 0
#define AOUT_LC_RESOLUTION_OPTION_M2 0
#define AOUT_LC_RESOLUTION_OPTION_M3 0
#define AOUT_LC_RESOLUTION_OPTION_M4 0

I'm interested in the third option, as it would give me 12bit cutoff and 12bit resonance CVs. But I'm not sure that I've understood it correctly, as option 2 is  not described on the info page on the AOUT-LC module (or the MBSID CV options page).

With options 0 and 1, the first LC module provides channels 1 and 2, the second LC module provides channels 3 and 4, and so on. Ok. So each board provides two CV outs, either 12 and 4 bit ones, or two 8 bit ones. But with option 2, which CV outputs on which modules give out the CVs?

1. Does it mean that the first LC module's first CV out gives a 12bit CV, the first LC module's second CV output gives another 12bit CV out, and then the second board's first CV out gives an 8bit CV out, and the second CV gives out nothing (or nothing useful)? Like so:

 

2. Or does it mean that the first LC module's first CV out gives a 12bit CV (=channel 1), the second LC module's first CV out gives a 12bit CV (=channel 2), the third LC module's first CV out gives an 8bit CV (channel 3), and the fourth channel (also on the 3rd LC module) doesn't do anything useful.

 

I guess I could also use option 1, and just use channel 1 (12bit) for cutoff and channel 3 (12bit) for resonance, and just leave the 4bit channels (2 and 4) unused?

With option 2, should my setup_8580.asm be changed to:

#define AOUT_LC_RESOLUTION_OPTION_M1 2
#define AOUT_LC_RESOLUTION_OPTION_M2 0
#define AOUT_LC_RESOLUTION_OPTION_M3 0
#define AOUT_LC_RESOLUTION_OPTION_M4 0

Or should it be:

#define AOUT_LC_RESOLUTION_OPTION_M1 2
#define AOUT_LC_RESOLUTION_OPTION_M2 2
#define AOUT_LC_RESOLUTION_OPTION_M3 0
#define AOUT_LC_RESOLUTION_OPTION_M4 0