SWRU622A August 2024 – September 2024 AWRL1432 , AWRL6432 , IWRL1432 , IWRL6432 , IWRL6432AOP
When the Flash device is not present or discoverable from the JEDEC response, the bootloader looks for an image to be loaded via SPI or UARTA interface, if the first ping/command is initiated through UART interface then RBL switch to UART mode of image download.
The UART communication protocol involves a simple command-response flow. The host first sends the command packet to the xWRLx432 device and then waits for a response from the device. Multi-byte fields are transmitted in big endian format with MSB bytes transmitted followed by the LSB bytes. Each command packet is immediately processed by the bootloader without any scheduling or processing in the background and then a valid response packet is sent. The response can either be an ACK, a NACK or it may contain some specific response information. For more details on booting over UART, see the AWRL6432, IWRL6432, AWRL1432, IWRL1432 Technical Reference Manual.