I've heard nothing yet. While I do understand that I2C clocking can vary, the fact that it varies this much for what should be a pretty standard I2C configuration is what troubles me, as well as the errors it appears to be causing. It's not pushing 400kHz no matter what I do, even with just a dummy ...

More info - I'm using GPIO21 for SDA and GPIO22 for SCL, which appear to be the defaults. Also, while the clock will drop somewhat with increased RC loading, the ESP32 is super-sensitive to it... I have to really work to get the Photon to react to increased capacitance, while the ESP32 readily drops...

I've been investigating this for a few days now, in both Arduino and in the IDF, and it's clear that the I2C clock significantly lags its set value. There's also another problem in terms of the duty cycle itself. I've looked at the ESP32 I2C HAL code and the way the clock is set is pretty straightfo...

I figured out what I did wrong, and wouldn't have asked had I not edited the wrong file. :| Once I straightened that out, I was good to go. Still, it's good to know more about newlib, so there's definitely that! Best of all - I've released another version of the RGB LED driver! The original code had...

So it's weird... here's the error: error: implicit declaration of function 'snprintf' [-Werror=implicit-function-declaration] note: include '<stdio.h>' or provide a declaration of 'snprintf' Turns out, if I #include <stdio.h> within the C code file itself, not just in the header file I'm already inc...

Does snprintf() exist for the ESP32? I see some references to it in esp-idf, but cannot actually seem to use it in code.

(If it just doesn't exist here, I'll work on including my own implementation.)

Along with several other updates, I'm now using the new interrupt allocator. Thanks again for the tip!

Followup: I got the RMT version of the WS2812 driver working in Arduino-ESP32 (the problem of driving NeoPixels is what prompted me to look into all this, though I still hope to gain more insight into the limits and quirks of GPIO):

https://github.com/MartyMacGyver/ESP32- ... ED-Drivers

You found the repo - and your fix worked! The update is pushed... I've got lots to do but getting this to work with the Arduino-ESP32 will hopefully be of benefit to those who wanted to see this working. I really appreciate your help - I still need to learn more about how everything operates at this...

I'm working on porting an RMT-driven NeoPixel/WS2812 driver to Arduino-ESP32 and in doing so I noticed that the main task is pinned to core 1: xTaskCreatePinnedToCore(loopTask, "loopTask", 4096, NULL, 1, NULL, 1); Why is that? I've run with core 0 and no core at all (just xTaskCreate) and my sketche...