M200 interfacing continues...

From: Sean 'Captain Napalm' Conner <spc_at_conman.org>
Date: Fri Jan 3 01:22:01 2003

In the original message, Sellam said:
> The timing diagram of the M200 says that the Index Mark is pulsed for 6
> microseconds. Now, if I'm computing this right, that is already less time
> than it takes for the 6502 to wait for the pulse to fall back to false
> from true. The 6502 takes 10 cycles, or roughly 10 microseconds, assuming
> a cycle is equivalent to a microsecond.

But in this message, Sellam said:
> The problem I'm having now is timing out too quickly on the first column
> read of the first card. According to the M200 docs I thought I had only
> a few dozen microseconds to sense the first IM but it is timing out with
> an 8-bit counter set to 255 and polling the IM signal in a loop that
> takes about 14 cycles (14 * 255 = ~3500 cycles).

  It actually sounds like the timing is 6 milliseconds, not 6 uSecs as
originally stated. If it is indeed 6 milliseconds, you then need to pause
for 6,000 cycles.

  -spc (But it sounds like you may know that already ... )
Received on Fri Jan 03 2003 - 01:22:01 GMT

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