Hi all

I am driving a DC motor with a Silabs c8051F040 the device(s) I am using are infineon BTN7960 (or 7970) which are very nice and easy to use High Current Half Bridge devices, I have them configured as an H bridge.

All my motor code is running fine and I was working on integrating some overcurrent protection on the system.

I am using the ADC0 (port 3.5 in particular) and I was wondering why I could not read any voltage on this port. After a long time thinking it was my code (I had nver used Port 3 ans AIN's before) I put a scope on the IS pin of the BTN7960, I had used a meter before this. and what do you know, it is giving a voltage that is switched at my PWM rate of 21kHz. Thinking about it of course it is.....

So My question is.....
How can I accurately calculate using the ADC on port 3.5 of the micro with no additional external filtering like a big capacitor, the voltage (which is proportional to current) over time?

ie, for a quick spike, I have a voltage and then for the rest of the time it is at 0v.

my process is slow so I can afford 1000mSecs to get the correct result.

I was thinking that I really have to run my ADC at a multiple of my PWM rate, like 84kHz or something huge, so that I can be sure to sample the voltage spike, and then I simply accumulate that data with all the 0v reading inbetween and that should give me the average voltage over time.....


This seems like a lot of work and fraught with danger, in missing the pulses, getting hung up doing the measuring that I can't do anything else and so on......

Any ideas?

Regards

Marshall