Bodmer
commented
5 years ago The problem is in the DS3231 library.
Within the DS3231 library dateFormat function the author has created a buffer to contain the result, this buffer only exists in that function and is released upon exit of the function. The function therefore returns a pointer to a buffer that no longer exists because the function ends! The ESP32 is very intolerant of coding errors like this. With other processors you can "get lucky" and the problem is a hidden latent bug.
You need to find a DS3231 library that is actively updated.
zoli2750
Hi Bodmer, I have encountered a "Guru Meditation Error: Core 1 panic'ed (LoadProhibited). Exception was unhandled." issue on my Widora Air clone. I'm on Arduino IDE 1.8.5, Win10, Board library installed today (version 1.0.0) from github/espressif/arduino-esp32
TFT and DS3231 not connected to the board, just the USB for the upload. PIN settings for the TFT is the standard in the user setup file.
Excpetion Decoder says: PC: 0x400d671e: TFT_eSPI::textWidth(char const*, int) at C:\Users\zoli\Documents\Arduino\libraries\TFT_eSPI\TFT_eSPI.cpp line 2271 EXCVADDR: 0x00000000
Decoding stack results 0x400d671e: TFT_eSPI::textWidth(char const, int) at C:\Users\zoli\Documents\Arduino\libraries\TFT_eSPI\TFT_eSPI.cpp line 2271 0x400d6745: TFT_eSPI::drawString(char const, int, int, int) at C:\Users\zoli\Documents\Arduino\libraries\TFT_eSPI\TFT_eSPI.cpp line 4299 0x400d1bea: loop() at C:\Users\zoli\Documents\Arduino\BasicOTA_ESP32zoli/BasicOTA_ESP32zoli.ino line 86 0x4012cafa: loopTask(void*) at C:\Users\zoli\AppData\Local\Arduino15\packages\esp32\hardware\esp32\1.0.0\cores\esp32\main.cpp line 17
The affected line in my sketch: tft.drawString(rtc.dateFormat("Y-m-d H:i:s", dt), 60, 20, 1); the same when the date format is shorter: tft.drawString(rtc.dateFormat("i:s", dt), 230, 80, 2);
Using the library: https://github.com/jarzebski/Arduino-DS3231 the problematic function in this library: https://github.com/jarzebski/Arduino-DS3231/blob/ea18fe451ac82b524f03a94e5ac27f172c00a1d9/DS3231.cpp#L171
Uncommenting the lines containing the dateformat function there is no Guru panic issue.
I assume the issue is that either the TFT_eSPI or the ESP32 core are have conflicting calculations for the length or for the width of a textstring when it is produced by a somewhat complex function.
On Nodemcu 1.0 12E there is no such problem, TFT displays the string : " rtc.dateFormat("Y-m-d H:i:s", dt) " correctly without any issue. You can surely assign it to the ESP32 support if there is no TFT_eSPI implication.