Posts Tagged ‘Racno ETC repair’

Ranco ETC-211000 uses AVR Atmega16L8

January 17, 2010

The Ranco ETC-211000 uses an Atmega16L8. The chip is initially protected so if you want to develop some code you will have to erase the chip first. The design is terrible, quit possible the worst i’ve ever seen in my reverse engineering time. ┬áMind you i have 20+ years experience. First of all there is a problem in the power supply in which voltage spikes can damage the onchip EEPROM, FLASH, and SRAM. They(Ranco, the engineer, the new guy) made their own RC-DAC from what i believe to a bit banged solution. The DAC is fed back into the analog comparator which then forms a ADC (most likely a staircase or SAR type). The lcd screen has 4 annunciators with 2 and 3/4 digits. At the time of this writing it is belived to be a static screen with a single common. 1/3 duty cycle seems to work fine. For more information on LCD screens check out Pacific Display Devices. Here is a rough-draft of the pinouts of the screen.