Step 1: LEDs Explanation
green on – patient successfully cured, fusebits repaired. If lockbits are enabled, just verify fusebits with factory ones – and if they ok – light up green.
red on – signature problem, can’t read, no device in socket, or no such signature in database.
green flashing – signature ok, fusebits are wrong. Lockbits enabled, chip erase permission required (read below).
red flashing – signature ok, no lockbits, but for some reason can’t write new fusebits, can’t pass verification after 10 attempts.
Step 2: How It Works
Step 3: Jumper Setting
chip erase – permit to erase whole flash memory. If lockbits are enabled, there is no possibility to set new fusebits. And there is only one way to disable lockbits – by erasing whole flash. Jumper close – permission to erase flash
unknown signature – it happens very rare, but it happens, that uC has erased signature. Signature, calibration bytes, and other data are not permanently stored in uC structure and they can be accidentally erased due to power supply spikes during programming or power cycling. Generally signature will be read as FF FF FF, but chip will work good, flash can be readed and written. If signature will not match to one from doctor database (FF FF FF or 00 00 00 too), closing this jumper will write a universal fusebits pack which will mess oscillator options and such, but will repair functionality of reset (disable RSTDISBL) and ISP programming (enable SPIEN). Microcontroller will be possible to further repair on SPI normal programmer. DO NOT use this option with Attiny11 or Attiny15.
Step 4: Download
ATTENTION: FIRMWARE IN BETA VERSION. I was not able to test all of the mentioned uC’s, so if something is going bad, please contact me and i immediately make corrections in code.
DOWNLOAD eagle 5.4.0 project files, PDF & PNG schematic and PCB’s
HEX & BIN beta firmware.
Project site: AVR Attiny Fusebit Doctor (HVSP) - check for code update
Coming soon: AVR Atmega Fusebit Doctor (HVPP)