On 10/12/05, Timothy J. Weber <tjweber@lightlink.com> wrote:
>
> You're right, thanks.
>
> I'd looked at that, but momentarily confused SPEN with TXEN.  Wishful
> thinking.
>
> Looks like I'm out of pins, so I need to either do the serial receive in
> software, or choose another chip.
>
> Thanks!

There's another option:

If you transmit continuous 0x00 out of the serial port, there is a
start bit, 8 low bits, and a stop bit. The start bit is low, the stop
bit is high.  So 90% of the time, the pin would be low.  (You could
even do 9-bit transmission, and make that 91% of the time).  Is 91%
good enough for you?  (Probably not, in a multiplexed LED array.  :( 
But I'll mention my idea anyway.)

When you need a high, you can stop transmitting, and the line will go high.

PS. I wrote some code to play audio on the TX pin of my PC's serial
port.  It doesn't sound too bad -- it takes a full ten minutes for the
headache to start!  Anyway, I'll post it once my blog is back online.

Regards,
Mark
markrages@gmail
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