I'm planning for a device with the ATmega64M1. To ease software development I'd like to be able to use Debugwire for debugging. As I understand it this requires programming the DWEN fuse, which disables the RESET function of the reset pin. This in turn removes the ability to use ISP as the reset function is gone. The only programming ability left is a kind of high voltage programming.
Am I correct with my understanding ?
In the case of the ATmega64M1, the only high voltage programming method seems to be parallel programming, is my reading of the datasheet correct ?
Parallel programming on the ATmega64M1 seems to need 18 pins, imposing severe constraints on the circuit. If using Debugwire requires resorting to debugwire, as it looks like to me, the I find this a severe restriction. In my case I think this makes Debugwire useless to me.