Want to drive 2-digit LED from PC

Thread Starter


Joined May 29, 2009

I got the circuit working now. I used a PicAxe18x as the microcontroller. I started out by buying the wrong type of display, I got two 74LS247 7-seg decoders and got a Common Cathode 2-digit display instead of common anode. By the time I found my mistake I already had everything breadboarded and it wasn't working. With the inclusion of three 74LS04 hex inverter chips, I sorted out the problem and got the displays to light.

Then... I miswired the data outputs on the PicAxe18x by following someone's advice on the PicAxe forum. Fortunately I was able to work around it with a couple of lookup lines in my code.

I'm sending the log file from the program out to the comport using a batchfile in cmd.exe, if it exists, then I delete the log. Since there is one instance in the log where the keyword I use to start reading the digits is used in a different fashion ("credits used" is first instead of "credits remaining"), I found a unique characteristic of that particular line (Action: Game End), I use findstr to send the other lines to the comport. The command is:

findstr /v /C:"Action: Game End" filename.ext >com1

This causes any lines that do not have the "Action: Game End" to be sent to the comport but lines with that string are skipped.


Joined Jul 1, 2008
Hi Wayne. I'm really glad to hear that you got the circuit working. Best of all, you did it with a Picaxe. I love turning people on to Picaxe, as they're so damn much fun to use and easy to learn. You're my second inductee here on the forum.