October 27, 2019

The slow SCK jumper on a USBasp dongle

About two weeks ago, I got fed up with all of this and put my USBasp dongles and all the parts pertaining to this project in a box and pushed them aside. I also ordered another batch of DIP package ATTiny13A chips from an Ebay seller. My thinking was that maybe the DIP package chips I ordered from AliExpress are all duds. Maybe there are just plastic with no chip inside. I really doubt it, but another sample will help me decide.

The chips arrived, and after letting them sit around for over a week, I decided to see what I could do with them. They give me the same sort of problems that the first batch did. It must be me doing something wrong.

I decided "just for the heck of it" to try installing the slow SCK jumper onto one of my USBasp boards. This is an unlabeled pair of pads marked JP3 on my boards. With this jumper installed, everything WORKS!. Why didn't anyone tell me this in the myriad of tutorials online? I now get: 

avrdude -c usbasp -p t13

avrdude: AVR device initialized and ready to accept instructions
Reading | ################################################## | 100% 0.02s
avrdude: Device signature = 0x1e9007 (probably t13)
avrdude: safemode: Fuses OK (E:FF, H:FF, L:6A)
avrdude done.  Thank you.
And again, AVRdude thanks me. What polite software!

I have 3 batches of ATtiny13A chips, and they all work nicely the same way. I don't deeply understand what this jumper does, and may or may not dig deep enough to find out. I am satisfied with just getting things done at this stage.

Oddly enough, it only seems to work with the voltage jumper in the 5V setting. It does not see the chip with the jumper on 3.3 volts.

I did through my junk box and find an old board with shorting jumpers, desolder three of them, and install them on my 3 USBasp boards. And all 3 board work! I am on to new and exciting things -- such as programming ATTiny13A chips!

Feedback? Questions? Drop me a line!

Tom's Light Info / tom@mmto.org