@AdamAnt You could replace the 200K with a 270K preset so that you can adjust it to give the maximum resolution. Remember that you are not measureing voltage with this set up, but an analog 'value' that is 'roughly' proportional to the voltage applied.

@mkaiser yes, that's correct

I had the same error and realized it was caused in combination with an interrupt routine . Having read the answers above I tried only to introduce this directive ICACHE_RAM_ATTR void Interrupt_routine() { ...code... } ... and it was all fine :)

@scalz Thanks for the link to the 3.3v USBASP mod! i have been pulling my hair out trying to get bare 328p chips programmed using a generic ASP thank you!!!

@adamant yes that's correct. The (other) difference is that the stock arduino version writes 0x00 to each location, while the MySensors version writes 0xFF. 0xFF is the value the eeprom has before it is written to the first time when it comes out of the factory.