we are currently testing BLE chip FR8000 FW update procedures over UART, and we got a situation that we think requires further analysis.

we downloaded over UART a new FW version in the chip and commanded reboot but after reboot the BLE chip does not work anymore meaning that the new FW does not start and we cannot erase or program anymore the chip using SWD interface.

probably we did some error in the UART update procedure (is under development), but the serious problem is that, from that moment, the chip can't be re-flashed with a valid FW even using the SWD interface.

when using JFlash we successfully connect to the device it's ok but sending Erase chip command we got errors or sending Erase sector we got errors also trying to Program the device results in errors.
During JFlash SWD operation, the FR8000 chip seems to reset itself several times.

Considering this problem from a general perspective, an error during FW transfer over UART is always possible and there should be a way to recover this situation by starting a new FW download over UART.

From FW upload documentation is seems that the new FW is copied in an alternative flash bank and only after checking CRC consistency the new FW is applied at reboot.
Is that statement, correct?

which is the root cause of the situation we generated with our UART FW update attempt?

Thank You for your support

Thanks. The attached example does not include AT command handling.
Starting from the ble_at example from the SDK, is there a complete example that also includes OTA UART?

I need to implement the OTA firmware update via UART and with AT commands.
The FR800X_sdk1.2_43ed3f4 SDK contains an example for AT commands, and evt.event_id = AT_RECV_UPGRADE_DATA is also provided.

The procedure begins with AT+MODE:U
at_ota_init(); --> missing api
chk_ret = check_whole_pkt_in_upgrade_mode(); --> missing api
but the code is not complete.

firmware upgrade process is expected while receiving from uart:
app_at_recv_c
if(gAT_ctrl_env.upgrade_start == true)
gAT_env.upgrade_data_processing == 0

Where can I find the complete code and manual?