Download a pre-compiled HEX file from the OpenEVSE Sources for your OpenEVSE product and your desired configuration.

Download the latest firmware and save files into a local folder. You will need 3 files: flash.bat, open_evse.hex and eeprom_24.bin

Run the flash.bat file. Programming and verification should take about 60 seconds.

If the command window pops up and goes away immediately there is a problem with the Device driver and/or the WinAVR installation.

Warning can not set SCK period is normal and can be ignored.