I am trying to use a attiny85 reset pin (data 5) as a output. I have a sketch loaded to control a 74HC4051, and have it working despite I need the 3rd data line to get the full 8 bits. It reads 4 bits now and sends the data over I2C (as I2C will use pins 0 and 2) Pin 1 reads the values and pins 3 and 4 is data select, where I need pin 5 to be the third select pin to get a fill 8 bits. It works fine at 8Mhz. I found the instructions and the calculator to reset the fuse (High fuse at 5F opposed to DF) and when I set the fuse using avrdude it takes and I can no longer program the chip, but at the same time I get nothing from the chip anymore. I will need to setup a HV programmer so I can recover the chip, but is there a different fuse I also have to set in order to use that pin as a output and still have I2C work? I have done this twice now and have two unresponsive chips, nothing over I2C now. Works fine until I change the High fuse to 5F to make data pin 5 work. Any suggestions??
Second related question, I have a ATTINY USB programmer, can I wire it on a breadboard and use a transistor to make the reset pin 12v and then just program it like normal, or do I have to reset the fulse first and then make changes and put the fuse back? Is the HV programmer just to reset fuses or can it be used to program the chip like normal? Thanks!