Tying wires to microcontroller pins

Thu, 03 Apr 2008 20:07:23 -0700

I finished building the MON08 programmer circuit last week, so the next step was to run wires from the circuit onto the connection points on the primary PCB.

At first, I tried soldering 0.25mm wire wrap wires onto the OSC1 and RESET pins on the micro-controller. However, the tip of my soldering iron was far too big (and blunt) for the job, allowing me to accidentally solder the tops first three pins together!

What a mess that was! I spent half an hour scraping it away with the tip of a 1.8mm slotted screw driver. Afterwards, I ensured that that the pins were once again unconnected, independent, and free using my trusty continuity tester.

With that soldering lesson well learned, I proceeded to try a different approach: I would literally tie wires onto the pins (see photo above). This was tricky.

I stripped off some insulation from each wire and bent the underlying metal into a crude “U” shaped hook. After much persistence (though mostly luck, it seemed) I was able to loop each wire around its corresponding pin. Then it was just a matter of twisting the excess length of metal around the insulation. Et viola! A metal knot. :-)

Finally, I secured the wires using masking tape so that they don’t move around and accidentally cause the knots to touch the neighboring microcontroller pins.

The road ahead

Now I need to solder 0.60mm wires to the remaining connection points
and try to read the micro-controller’s flash EEPROM.

Initially, I thought I would have to install Windows XP on my computer (groan!) just to use the ICS08JBZ programmer software to communicate with my MON08 programmer circuit. But luckily, I found an excellent open source tool called monitor-68HC08 written by DEMAINE Benoît-Pierre which does the job. This tool’s source code will come in handy if I end up having to crack the microcontroller’s security code by brute force.

OpenAG5 project

Tying wires to microcontroller pins

The road ahead