round of applaue everyone, it has taken HOURS every day for a few days to crack this problem.
And cracked I beleive the problem is.
The problem was in the earth supply to the max chip. I'm still trying to work out why as the traces seem okay, but they have very high resistance (well, virtually no conductivity whatsoever). They look fine, it's only when you multimeter that specific trace do you realise 'oh bugger'.
So - a simple fix. I knew it would be, but i couldn't think for hell what it could be i'd tried everything. I allowed myself to be convinced that because the pic was receiving changing voltages at the uart when data was being transmitted, and that the idle voltages on both rs232 and ttl sides of the max were okay, that it's power supply was okay too. It wasn't.
This is one for the books.
And cracked I beleive the problem is.
The problem was in the earth supply to the max chip. I'm still trying to work out why as the traces seem okay, but they have very high resistance (well, virtually no conductivity whatsoever). They look fine, it's only when you multimeter that specific trace do you realise 'oh bugger'.
So - a simple fix. I knew it would be, but i couldn't think for hell what it could be i'd tried everything. I allowed myself to be convinced that because the pic was receiving changing voltages at the uart when data was being transmitted, and that the idle voltages on both rs232 and ttl sides of the max were okay, that it's power supply was okay too. It wasn't.
This is one for the books.