Hi There!
I use Heltec Lora v2 and an Arduino Mega 2560 MCU. Both establish communication over Serial with each other. I have to use a logic level converter because ardu use 5 V as High logic level, and Heltec use 3.3 V as High logic level (ESP32 based). Heltec Lora v2 board has a 0.96 Oled display, and sometimes (randomly), the characters of the display are dissappearing, and the Heltec Lora v2 MCU seems to out of order. Maybe it always resets itself, but never reaches loop(). When I unplug then plug in back the wire from 3.3 V pin of the Heltec, then the board works correctly again. Then after some times it does it again. What could be the problem? I changed the logic level converter, selected different pins in Heltec lora v2, changed the wires. Nothing helped me.
The Serial Output is: rst:0x10 (RTCWDT_RTC_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT)
flash read err, 1000
ets_main.c 371
When I want to upload sketch to Heltec Lora v2 I have to unplug 3.3V pin connection from Heltec Lora v2 to upload properly the firmware, and when I want to connect via Serial (mini USB) with terminal I also have to unplug 3.3V pin wire.
Here is the connection:
I use this logic level converter: LINK
So the Serial connection is:
on Heltec Lora side:
3.3 V from Heltec to Logic level converter’s low voltage input
GND from Heltec to Logic level converter’s GND input
RX from Heltec to Logic level converter’s RX input
TX from Heltec to Logic level converter’s TX input
MEGA.begin(115200,SERIAL_8N1, 13, 12); //RX, TX
on Arduino Side:
5 V from Ardu to Logic level converter’s high voltage input
GND from Ardu to Logic level converter’s GND input
RX from Ardu to Logic level converter’s TX input
TX from Ardu to Logic level converter’s RX input
Here is the code where I start Serial communication on Heltec Lora V2 side:
Here is pinout diagram LINK
And I forgot to mention that I use another Arduino Mega 2560 with a same Heltec Lora v2 with the same Logic level shifter with the same connection and pins, and that Heltec Lora v2 does not freeze/reset and I don’t have to unplug the 3.3 V pin when I wan to upload a new firmware, and the Serial communication works continously.
Thanks in advance!