New Mega88AP with entirely default fuses (no BOD, 1Mhz etc). 10k pullup to VCC on the reset line.
+ If I run it at 5V, all is well
+ if won't run if powered from a stable 2.0V/120mA buck.
+ If I reset the AVR at 2.0V, even repeatedly, it doesn't start.
+ If I ground the reset line, apply 2.0V power, and release the 2.0V reset line, the AVR doesn't start either.
+ If, with the VCC power on, stable at 2V (and the AVR not started as mentioned) I prode the reset line with 5V, the AVR starts (without even puling the pin down/up!)
+ Any further reset (with the normal 2V line) works fine once the AVR is running.
As mentioned, I don't have a BOD, and I tried with two different AVR. same behaviour..
I just don't understand, it's like that AVR is "hung" in power-on-reset, despite being given .2V over it's spec.
The code on the AVR is tiny. It disables most peripherals in the PRR, first thing.
Anyone see that before ? tried a LOT of things already (caps on reset etc) with no differences...