6502.org

Posted: **Fri Nov 01, 2024 7:50 pm**

Hello.

I found this schematic on how to drive a simple 3-bit DAC with a VIA (CB2).

http://wilsonminesco.com/6502interrupts/index.html#3.3

However, I was wondering if I could do the same thing with CA2. I'm reading over the data sheet but I'm just not getting how all of the timers work or I'm not finding how a timer can output data out to CA2 or CB2.

If that circuit only works with CB2, I will just have to swap my ports around. But I'd rather not if I don't have to.

Thanks!

Posted: **Fri Nov 01, 2024 8:27 pm**

The VIA's SR (shift-register serial port) is confined to using CB2 for data and CB1 for clock. If the clock is controlled by a VIA timer, it will be T2. There are quite a few modes of operation for each; but as is the case also with microcontrollers, the various timers and pins have limitations in the mix-and-match options.

Posted: **Fri Nov 01, 2024 8:52 pm**

GARTHWILSON wrote:

The VIA's SR (shift-register serial port) is confined to using CB2 for data and CB1 for clock. If the clock is controlled by a VIA timer, it will be T2. There are quite a few modes of operation for each; but as is the case also with microcontrollers, the various timers and pins have limitations in the mix-and-match options.

Dang it! I was afraid of that. LOL.

Well, I will just have to swap the two ports so no big deal.

BTW, one of the biggest reasons I am building this one is so that I can tinker with these chips and not have to ask so many questions.

Thanks!

6502.org

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Re: Driving a 3-bit DAC from a VIA