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Friday, 27 June 2014

Programming Shrimps - the best laid plans...

I'm working on the preparations for my Monday evening Shrimping session at BCS SPA 2014, and as always things are taking a little longer than planned.

Phenoptix AVR ISP
I got an AVR ISP shield from Phenoptix a while back and verified that it would program the chips I need for Monday. It has standard IC sockets, which means that you need to be a bit careful when removing the chips after you've burned the bootloader. If you don't do a straight pull you can bend the legs of the chip and the damage can make the chip unusable.

I decided a few days ago that I'd use a Zero Insertion Force (ZIF) socket for the programming. These allow you to drop a chip in, close the gripper of the ZIF, program the chip and then release it. You can then remove the chip easily without any risk of damage.
ZIF Socket

It's a ZIF socket, Jim, but not as we know it

I got a couple of sockets which were surprisingly hard to find in the UK. When they arrived I discovered that they had pins 0.6" apart, rather than the 0.3" that the Phenoptix board expects.

No problem, thought I. I can use a bit of stripboard and add two rows of header pins 0.3" apart, solder in the ZIF socket, and plug the whole thing into the Phenoptix shield.

Today I tried. It won't work, because the pins on the ZIF socket are too short. Even worse, the pins are so short that they won't work reliably in a breadboard.

Plan B - DIY ISP

DIY ISP
So here I am, at 6 PM on a Friday evening, soldering up my very own ISP shield based around the ZIF socket. I'm nearly done, and will finish it tomorrow, but a task that should have taken 5 minutes will end up taking the best part of a day.

Luckily I still have plenty of time in hand, so don't worry if you're planning to attend Monday's Shrimping session.

If you are coming to Monday's Diversion

Remember:

  • Sign up on Monday Morning. We're limited to twenty people.
  • Bring a Laptop with WiFi and a spare USB port, and
  • Install version 1.0.5 of the Arduino IDE before you come