You're a star. All working now, thank you. My mistake was to install the "SER"driver because I thought this was … err … a serial device. And although I'd previously read the excellent guide at One Transistor, I'd missed the bit about using the PAR driver. Wonderful.

I’d appreciate some very basic advice on CH341x programmers. I know this topic comes up from time to time, but stuff changes, so I hope a refresh is in order. In particular, I see some unexpected things happening with jumper positions.

[My plan is to learn to read and write 24CO2 EEPROMs via I2C. The first target is the one in my Uni-T clamp meter, but before tackling that I have some brand-new EEPROMs to practice on.]

I have two basic Chinese programmers. One is the blue board with a CH341A and two rows of pin headers. To my untrained eye it looks like all the others....

Greetings all. Charles here from Norfolk, UK. Now retired from engineering journalism and marketing, I've revived my youthful interest in electronics and am proud to volunteer at a repair café in my town. My experience is pretty limited but we do see a lot of SMPSs!...