September 23, 2024

Biscotti firmware -- rescued by Pomona

An 8 pin SOIC clip by Pomona saved the day! I'll tell the whole story here.

As mentioned previously I took apart one of my Convoy S2+ flashlights. Once the driver PCB was exposed I took a good look at it and could see that pin 5 was soldered (to ground apparently). I got out my dremel tool with a fine bit and cut the trace. I'll note that a DIP package device on a breadboard works just fine with this pin floating, so there is no urgent need to reestablish this connection when flashing is finished.

I then tried many things using some inexpensive SOIC clips I purchased from somewhere (I have two, and neither of them work). They do work to flash code into an ATtiny13 I pull out of a tube of loose devices that I bought "just in case). So my wiring is at least correct.

I bit the bullet and purchased a "Pomona Electronics 5250 8-Pin Gold Plated SOIC Clip Test Clip with 0.1" Lead Spacing". It cost me $26.76. I connected it to my usbASP and it worked the first time without any fuss. I was able to read and double check fuses and burn an image.

So, you can buy worthless no-name test clips for $9.00 or so, but you will be sorry. My results with the Pomona:

make rfuse
avrdude -p attiny13 -c usbasp -B10 -U hfuse:r:-:h -U lfuse:r:-:h
Processing -U hfuse:r:-:h
Reading hfuse memory ...
Writing 1 byte to output file 
0xff

Processing -U lfuse:r:-:h
Reading lfuse memory ...
Writing 1 byte to output file 
0x75

make flash
avrdude -p attiny13 -c usbasp -B10 -U flash:w:biscuit.hex
Set SCK frequency to 93750 Hz
Set SCK frequency to 93750 Hz
Reading 288 bytes for flash from input file biscuit.hex
Writing 288 bytes to flash
Writing | ################################################## | 100% 2.15 s
Reading | ################################################## | 100% 1.63 s
288 bytes of flash verified

Avrdude done.  Thank you.
Now I just need to replace the driver back into the flashlight. This will require soldering the PCB back into the brass "pill". Then I can try things out.
Feedback? Questions? Drop me a line!

Tom's Light Info / [email protected]