Debugging an Arduino

Yesterday I sat down to try and write some debug code for my sensor detector only to realize debugging a microcontroller is going to be more difficult than normal that normal software.

The only loop in the program is the main ‘loop’ procedure which is a standard arduino function. This procedure is called thousands of times a second.

To start the debugging, I need to know which of the procedures in this ‘outerblock’ is called when it goes into lala land.

I can’t just print a debug msg before each proc is called as the serial interface is way too slow for that. I decided to xmit a packet as each proc was called and then I’d look at the last packet when the problem occurred. Right. Within a minute thousands of packets were generated.

I had to stand back and think about the problem again.

I can’t really communicate with anything except memory. But when the hang occurs, I loose control and can’t dump memory.

BUT, I think that interrupts are probably still working since the problem must be a loop in a driver. So my current thought is to write to memory an identifier indicating where I am currently. Then I will have a watchdog timer running on an interrupt. If the watchdog sees the program is no longer running, it can send a debug packet and report the last procedure called.

Now just have to implement the idea.

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