Let's Make Robots!

PicAxe 20X2 mainboard

This is the second board I received from sparkfun / batchPCB. The other one, a motor driver, is tested and done.

This one came with the same design fault: too small holes for the resistors. i'll have some work getting them mounted. Perhaps I should solder them to the surface instead of drilling out the holes. Drilling tends to destroy the solder pads and the through connection, making it next to impossible to properly solder anything.

There are 4 transistor buffered outputs (bottom left) and two general purpose outputs (or inputs). A socket for an EEPROM is on board as wel as a I2C port with a jumper to connect or disconnect the I2C pull up resistors (4K7).

The C-port pins, on the left of the picaxe are all general purpose (IO, V, Gnd) and the last 4 can be pulled down with 10K resistors that are connected with a DIP switch so that the pull downs can be disconnected if needed.

J3 is used to connect a jack for programming the picaxe. (Gnd, Serial-In, Serial-Out)

The board is 43mm x 58mm.

I'll add more info and a picture when I have the components mounted and did some testing. Everything has been tested and works perfectly.

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Hey Mv, nice work but now I 'm curious, do you know which resistors component you used? I have a few designs I've been kicking around but haven't submited yet, so want to prevent running into the same issue.

I got the resistors mounted by drilling next to the pads instead of in the center. That way the pad stays intact so there is something left to solder on after the drilling. That is why the resistors are not mounted straight in the picture.

I was using the RES300 in DIPtrace. The RES400 is the correct size for regular resistors. You can check this by right clicking a pad and opening pad-properties. That will show you the pad size and hole size.

But you could also alter the pad properties of the Res300. 

I figured you had to drill close but not into the main hole for the pad for the exact reason you mentioned...

Hrmm....are the RES300's around the size of the 1/8watt resistors? I don't recall the size I had set on mine, but will take a look at it when I get home this eve. Does anyone know where to find the info on what res300, etc means?

I just changed the board designs without replacing the Res300 with res400. When click a pad and change the size, you have the option to change "all similar pads" so that will fix them all in one go.

I'll use the res400 in new designs, but this trick will help to quickly fix existing designs

I looked at my 2 latest designs and they use the res300....ah man, I'm glad I held off on sending mine to get produced!!

I'll have to try the trick you mentioned...thats a life and time saver!


The R300 pattern is correct, but it is for the tiny 1/4 watt resistors. They have a finer leg comming out of them. I have run into this same problem as after I got my boards, I found out that the value I needed was not available locally in a 1/4w version. I too, drilled out the holes and destroyed the pads. I ended up surface-soldering as well. It sorta sucks because those tiny little resistors sure do fit well a lot of places. --Great to hid under the pic itself.