Archive for July, 2012

OS X ATtiny25 Programming Walkthrough

Saturday, July 7th, 2012

A while back I bought a batch of ATtiny25 microcontrollers and today I finally put one to use and got it programmed. MIT’s High-Low Tech group has put together a really nice package for programming ATtiny45s and ATtiny85s from the Arduino IDE, but it doesn’t support ATtiny25s, presumably because the limited memory doesn’t leave enough space after the bootloader is installed. I had a dickens of a time trying to find instructions to walk through programming an ATtiny25, much less on OS X; but it turned out to be pretty easy after pulling together a few separate resources. Here’s the path to blinkemness.

ATtiny25 board with USBtinyISP and Saleae Logic, overhead view


Hand-Soldering SOIC

Monday, July 2nd, 2012

I wouldn’t want to do it for a living, but it’s an enjoyable diversion once in a while, particularly as a favor for a friend.

Breakout boards with SOIC

I aligned each chip’s pins by hand, clamped it to the board with a gator clamp (with heatshrinked jaws), soldered the far row of pins, rotated the board, and soldered the now-far row of pins.

Three rows I was able to do by blob-and-drag (heat the pins at the uphill end of the row, make a big solder blob, and drag it down the row at a pace slow enough to heat the pins but fast enough to keep the surface of the blob from oxidizing too badly, trusting surface tension to bring the blob with you and leave only a lovely solder fillet below each pin). Three rows I ended up doing slop-and-wick (get solder all over the place, then use “Size: Good” solder braid to remove solder bridges from between the pins, leaving a lovely solder fillet below each pin and evidence scorched flux everywhere).

I’d take recommendations on a good flux remover — preferably detailed recommendations indicating whether you have to scrub or just spray, how cleanly it washes off, etc. You can see that the rubbing alcohol I used leaves a bit of residue.