Cybords by Ward Cunningham.

I think I might use Bynase in my "World's Dumbest Calculator" project. I don't understand cybords, but I want to. I got the bynase2.inc file and built a simple cybord on a Tiny13 chip. I figured a ramp would be a good thing to have, so my first try was as follows:

main:
 inc byout
 rcall byop
 rcall bydle
 rjmp main

I put an LED and a current limiting resistor from PO to ground. Worked like a lead balloon (not at all).

Sat and thought awhile. Part of my problem is I don't understand how to debug these things. Perhaps I should download the pre-defined cybords and see if I can get them working.

After some thought I decided to slow my ramp down. I have a 256 count delay (decrement R17 until it underflows, then decrement byout). Not much better. So I changed it to decrement byout every fourth time through the loop. Now it goes from dim to bright slow enough to watch it. I put the voltmeter on PO and it was going from zero to about half a volt.

Took another look at the specification on c2.com. Bynase puts a high signal than waits hundreds of counts before repeating. I guess in a way I'm doing a very low-level PWM signal. So the LED lights up but not as much as I want. My next step is to add a second cybord chip that listens to signals on PI and translates the value to a real PWM signal. Have to figure out the settings for the timer to do PWM. Or I could just get the TV output ported to Tiny13. The ValueFilterMeter would help me see what is on the bynase circuit.

Eventually I plan to have a Tiny2313 read the 8-bit input switchbank and send the calculator status on two bynase signals. One for the input number and one for the accumulator. The Tiny2313 already on the display board will read the bynase signals and update the LED outputs.