How do I automatically set the baud rate on a LoRa® module?

All of the RN2xx3 module’s settings and commands are transmitted over UART using the ASCII interface. The default settings for the UART interface are 57,600 bps, 8 bits, no parity, 1 stop bit, no flow control. The baud rate can be changed by triggering the auto-baud detection sequence of the module. To do this, the host system needs to transmit to the module a break condition followed by a 0x55 character at the new baud rate. The auto-baud detection mechanism can also be triggered during sleep to wake the module up before the predetermined time has expired.

A break condition is signaled to the module by keeping the UART_RX pin low for longer than the time to transmit a complete character. For example, at the default baud rate of 57,600 bps keeping the UART_RX pin low for 938 us is a valid break condition, whereas at 9,600 bps this would be interpreted as a 0x00 character. Thus, the break condition needs to be long enough to still be interpreted as such at the baud rate that is currently in use.

For more information, read the "RN2483 LoRa® Technology Module Command Reference User’s Guide".

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