Hi Andy,

I think you have misunderstood my previous post, what I mean is when you have 64kbyte of program to play about with and compilers are so cheap(certainly for the AVR), it makes sense to use a compiler, in fact I have done some test's on the '51, I wrote my own bit banging routine for the MCP3302 12bit+sign adc, at the start of the routine I set a port pin low and at the end of the routine set the port pin high and then measure aquisition speed on a scope, I wrote the same code using my compiler, and although the asembler was faster it was very marginal, not much difference in speed.
As I've said elsewhere, I have a LCR meter prototype on my bench using a '51 processor, the communication with the adc is written in assembler.
the processor first samples 32 16 bit integer bins, sampling then stops after 32 bins have been read and the processor then converts all the 16 bit bins into 32 bit floats and then the data is passed through the fft routine which takes about 300mSec to complete.
Now the interesting thing is on the AVR, the integral 10bit adc can be made to free run and interrupt the processor when the conversion is finished, great idea because the processor is not tied up bit banging for a value, the problem is, I'm experiencing chronic chross talk between channels, when used in differential mode.

cheers
JA