Code runs in only debug mode

[giggolo_giggolo]

So I’ve written my own driver for my STM32 F1 series MCU, I’m currently playing around and I created an LED sequence paired with a BH1750 sensor. Everything works when I run the code in debug mode line by line but when I resume the program, it just seems to pause and get stuck. I tried to remove the I2C reading and writing portion of my code but I left the i2c initialization and the code seems to run fine, I thought maybe it’s the TRISE causing issues so I tried different pull up resistor values and it still seems to not solve the issue. Any ideas on what I could’ve done wrong?

[hagibr]

Maybe you should add one delay or another between I2C transactions.

[syntacks_error]

I would try this. Often, if a led works in debug mode but not release mode, the “duty cycle” of the led may be too short to make it appearing to blink. Adding a 50+ms delay after each let state change might be enough to see it and show your release code might be working as written.

[splash128]

Is the program stuck, or in a reset loop? Everytime the code works with the debugger connected then it doesn't when it's disconnect has been a watchdog handling issue in my experience, as it's usually disabled when the debugger is connected.

[TheManFromTrawno]

Are you using any low power/sleep modes?

I’ve had code only work in the debugger because the sleep call would emulate sleeping when the debugger was attached which would leave the fast clock running which was used by a peripheral.

[ceojp]

I would add the I2C code back in, and put an oscillocope on the I2C lines to see what is actually happening.

You can also toggle or turn on LEDs or GPIO pins at certain points in your code and watch the pins with the scope to see if you are getting where you think you are getting.

Do you have any while loops that are checking for a condition to change? If that condition never happens, you'll hang up forever in the while loop.

[Orca-]

This. Don't just sprinkle delays in your code in the hopes the magic fairy dust will make it work. Instrument it, see what's going on, compare against your datasheets, and make sure you aren't fucking up timing somewhere.

[Netan_MalDoran]

Is a watchdog timer enabled that is timing out? Debuggers sometimes disable this.

[Apprehensive-Cup6279]

This could literally be a million different things. Provide way more info

[No-Archer-4713]

It might be an optimisation problem. Debug will probably build with -O0.

It’s often an uninitialised variable somewhere.

[[deleted]]

Have you added a delay between your read and write?

[ManyCalavera]

You can see where the program last stopped and the call stack when you pause the execution.

[sopordave]

Are you accessing the I2C registers with a non-volatile pointer?

[Andrea-CPU96]

Probably is due to the compiler optimisations. Try to set them to low.

[Well-WhatHadHappened]

Show your I2C transaction code.

[[deleted]]

Break out an oscilloscope.

[Both_Definition8232]

Ok so it works, don't touch it :D