I am trying to interface a megaAVR (it'll be a 103L, even though at the moment I only got a 163L sample), operating at 3.3V, to a 5V LCDisplay. Unfortunately I will have to read data from the display occasionally (and the Busy line), so that I need some kind of 5V --> 3.3V conversion. The AVR is aparantly not 5V tolerant (datasheet says Vcc +0.5V max).
Are the port outputs of the AVR clamped to Vcc with internal diodes ?
I mean, in order to protect the AVR port outputs, would it be sufficient to put e.g. 1kOhm resistors in series ? (AVR port - resistor - LCD port)
Of course it would increase current consumption, but most of the time the lines are tri-stated anyway. I just don't want to damage the AVR.
The 4MHz megaAVR103L will work from 2.7V, according to the datasheet.
The 6MHz megaAVR103 starts at 4V ...
can I naivly just draw a line between 2.7V/4MHz and 4V/6MHz, and operate a megaAVR103L at 3.4Volts and 4.9152MHz ?
Any help is appreciated,