Try adding -e to the upload_flags of the platformio.ini for an erase.
The upload_flag took care of the error. The SCA-GND voltage is now 5V but SDA-GND is 2.18V so I tried with a 1.5kΩ resistor on PB0 and raised it to 2.6V. If I disconnect the SDA & SCL wires and measure voltages on PB0 and PB2 I get 1.4V and 1.8V. I don’t know if that is normal or not. How can I test the Sparkfun Programmer for faults?
maxgerhardt
I sent a question to Sparkfun through their support page explaining the problems I have with the voltage levels and this is what they said:
AVR Tiny Programmer is only intended to program an ATtiny, it can’t act as a development board after programming. The reason it won’t work is the circuitry on the programmer will interfere with any attached device that’s not an ATtiny.
If you remove your chip from the programmer it should function as programmed though.
So I’m using the programmer in a way it wasn’t intended for. It makes sense, or …?
Well makes sense to me, I didn’t take into account what other circuitry you have on the programmer. Probably explains why it’s working so painlessly for me and Digistump ATTiny85 board, it gets programmed via only two USB lines (D+, D-) and I don’t use those pins for display or UART so they’re all free.