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SubjectRe: Sounds suspiciously like a homework question :) *nt* Reply to this message
Posted bysellenoff
Posted on08/10/04 11:53 PM



Thanks Riff!

Yes, it is the 68B09, and i'm glad you pointed out that the previous versions of the chip showed E & Q as inputs, since I was quite confused when 2 different sets of data sheets showed the pins differently..

I'll check out seeing how it sounds with 1/2 the freq, thanks!


> If you look at Figure 10 - Clock Generator in the Motorola 6809 Technical Data
> manual, you will notice that E and Q are both nominally half the frequency of
> the input XTAL frequency. If XTAL is nominally 8 Mhz, E is nominally 4 Mhz.
> Looking at the clock generator example you should also be aware that it is not
> always the case that E and Q are always half the frequency of XTAL. In the
> clock generator circuit, an extra flip-flop is used to generate a signal which
> adds wait states, causing the duty cycle of E and Q to be stretched out. There
> may be a limit to how long E and Q can be stretched out. If a 6908B is being
> used then you don't need to worry about it as the E and Q pins are outputs. The
> E and Q inputs are meant to provide a means of external synchronization, but I'd
> have to read through the 6809 manual again to be sure that the internally
> generated E and Q signal frequencies are constant. If they werent, they
> probably wouldnt be used for triggering sound generation, so its probably not an
> issue, allowing for the assumption that they are always clocked at half the
> frequency of the oscillator input.
>




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Entire Thread
Subject  Posted byPosted On
*E & Q timing on M6809  sellenoff08/09/04 06:15 PM
.*Sounds suspiciously like a homework question :) *nt*  Bart T.08/09/04 11:55 PM
..*Re: Sounds suspiciously like a homework question :) *nt*  sellenoff08/10/04 12:22 PM
...*Re: Sounds suspiciously like a homework question :) *nt*  Bart T.08/10/04 09:12 PM
....*Re: Sounds suspiciously like a homework question :) *nt*  sellenoff08/10/04 11:56 PM
...*Re: Sounds suspiciously like a homework question :) *nt*  Riff08/10/04 08:21 PM
.....Re: Sounds suspiciously like a homework question :) *nt*  sellenoff08/10/04 11:53 PM