I have a couple Attiny85 based USB development boards (or rather, cheap Digispark clones from Ebay). The pin 5 seems to be always at high, no matter what I do. I am suspecting the manufacturer didn't disabled the reset. And hence it is pulled up internally.
Can someone please confirm this? I am tempted to lock the reset bit, but this means I can no longer program with over ISP. So I am hesitent.
Best Answer
nRESET does indeed source approximately Vcc when the RSTDISBL fuse is unprogrammed. Since this is meant to be a USB development platform, you should burn (and test) Micronucleus to the chip before programming the fuse.