Details: I have our external MCU (STM32L4R5ZI) UART connected to RAK4270 UART1. I chose to use UART1 so that we might write a firmware updater that runs on our MCU. I see that the RAK internal bootloader uses YModem protocol, do you publish the details for communicating with your internal RAK bootloader so that we can write our own RAK4270 firmware updater that runs on our MCU?
You can update the firmware using YModem procotol, as you already find out. The command sequence for the firmware update is:
The firmware upgrade uses the Ymodem protocol. Two command operations are required before upgrading. The command sequence to start the update is:
at+boot\r\n
at+update\r\n
Send new firmware using Ymodem protocol to upgrade.