I have an SeP32S3 connected to RAK3172, We read serial printline from the ESP which gives information about the data sent to the RAK.
The MCU UART is connected to UART2 of the RAK and we are able to send and receive AT commands through the MCU. Right after flashing the MCU OTA, the LoRa is lost (Does not send OK upon sending AT requests from the MCU to the LoRa onboard). Functionality is restored when we do power reset.
We tried to jump the reset pin on the RAK to GND, we got an info stating that Lora was reset to LoraWAN then the serial port is not printing anything.
The hardware connection is good since we are able to restore comms after a power reset.
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I cannot follow your setup. Maybe you can clarify some details:
ESP32 performed an OTA update then RAK3172 stop responding on its command via UART2? What are the changes implemented on OTA? New commands? New UART speed?
When you say functionality is restored after power reset, is it working again? I am confused here because on the next statements, you said Lora was reset to LoraWAN then the serial port is not printinng.
What is your power source of RAK3172? Is it stable?
We have an ESP32S3 development board connected to RAK3172 breakout board, We read serial print line from the ESP which gives information about the data sent to the RAK Like below.
RUI firmware version 4.
The OTA is for the development code on the ESP, we are not touching the RAK firmware. Moreover, we don’t change any parameters in the code or RAK. After the firmware is uploaded OTA to the ESP, the LoRa is lost (Does not send OK upon sending AT requests from the ESP to the LoRa onboard). LoRa functionality is restored when we do power reset. We get the screenshot below.
The ESP powers the RAK through the 3.3VDC pins. When connecting the RAK to an external power supply and have a common GND between ESP and RAK, we get nothing in the serial (without OTA, just ordinary send and receive) like below.
Can you advise why this happens?
We found that driving the RST pin low through a GPIO pin restores connection to the RAK when it is powered through the ESP.
This is a strange behavior. The module will have limited AT command response if it goes to Bootloader mode either RUI3 or STM32 Bootloader. We have hanging issues before but we fixed this already on v4.0.5 and usually requires reupload of firmware. In your case, you can recover it via reset.
My suggestion is monitor UART lines, VDD supply line and BOOT pin. It will be helpful to see what is happening on this lines during OTA of ESP32.
As with external power issue of no communication between RAK3172 and ESP32, this is highly likely a setup/wiring issue (if you can confirm that RAK3172 is working if you send commands to it direct).
