4 ms·

This has been analysed extensively on our forum and the root cause was a bug in the software serial Arduino library as well as a slightly wrong command send fro

This has been analysed extensively on our forum and the root cause was a bug in the software serial Arduino library as well as a slightly wrong command send from our library. Details [1] [1] https://forum.airgradient.com/t/co2-reading-of-3-constantly/605/6 https://forum.airgradient.com/t/co2-reading-of-3-constantly/...

mtlmtlmtlmtl 3y ago
Arduino library eh? Would definitely recommend getting away from that as soon as possible. When I worked with avr controllers we eventually ended up writing all of our own library code because it was still faster than trying to debug these strange heisenbugs caused by gnarly bugs in the libraries. I specifically remember softserial was very problematic, and actually reading the code convinced me to dump it. Might be fixed now, but there's timing code in there that could easily break on a compiler update because it's still written in C++ and has handcounted delays based on counting instructions in compiler output. Now, maybe they recheck those on every single release of avr-gcc to make sure the count didn't change, but why rely on that? We're talking about the same maintainers here who kept conditionally compiled ASM code to manually push and pop the stack in every function because some absolutely ancient MacOS 9(or something like that) version of GCC somehow didn't emit those instructions. That was still there in 2015, hopefully they removed it since then... It also sets interrupts. I don't like library code doing this at all. I wanted complete control over that so I always know what interrupts might occur. And even worse it uses a circular buffer for storing data but IIRC offers no method of detecting a full buffer. Which led to a lot of "fun" debugging. Arduino libraries are fine for simple prototyping, but they're not high quality enough for writing reliable microcontroller code.
- rgovostes 3y ago
  Is there a library that you do recommend using for serial comms?

mtlmtlmtlmtl 3y ago

Arduino library eh? Would definitely recommend getting away from that as soon as possible. When I worked with avr controllers we eventually ended up writing all of our own library code because it was still faster than trying to debug these strange heisenbugs caused by gnarly bugs in the libraries. I specifically remember softserial was very problematic, and actually reading the code convinced me to dump it. Might be fixed now, but there's timing code in there that could easily break on a compiler update because it's still written in C++ and has handcounted delays based on counting instructions in compiler output. Now, maybe they recheck those on every single release of avr-gcc to make sure the count didn't change, but why rely on that? We're talking about the same maintainers here who kept conditionally compiled ASM code to manually push and pop the stack in every function because some absolutely ancient MacOS 9(or something like that) version of GCC somehow didn't emit those instructions. That was still there in 2015, hopefully they removed it since then... It also sets interrupts. I don't like library code doing this at all. I wanted complete control over that so I always know what interrupts might occur. And even worse it uses a circular buffer for storing data but IIRC offers no method of detecting a full buffer. Which led to a lot of "fun" debugging. Arduino libraries are fine for simple prototyping, but they're not high quality enough for writing reliable microcontroller code.

rgovostes 3y ago
Is there a library that you do recommend using for serial comms?