Firmware update (DFU) on NRF52

[Felipe Ribas]

Hi,

just a simple question: I need to create an update over the air system with my nrf52 and I was wondering if transferring the new image to the chip requires especial UART communication or something like this? The reason of my question is because I will have 2 separate BLE chips but one is going to have the radio off and the only connection between them is an one wire bus system (LIN bus). Can I use this to transfer the new image and then trigger the update all over this bus system? Note that between the LIN bus and the BLE there is a LIN<->UART chip.

[bjorn-spockeli]

First of all, which SDK and SoftDevice versions are you using? Second, which BLE chip is going to have its radio turned off, the nRF52 or the other one? It could sound like you want to update the nRF52 over UART.

[Felipe Ribas]

Sorry, I didn't specify properly. I'm using a pair of nRF52832 talking to each other via LIN bus. As the nRF doesn't support LIN natively there is also a UART-LIN between the nRFs. One of them has the radio off and it's only receiving infos from the other one. Will I be able to implement some OTA update via this serial connection? The softdevice I'm using is the s132

[bjorn-spockeli]

Yes, I think that should be possible, you will have to flash the BLE bootloader to the one that has the radio turned on and the serial bootloader to the one on the other nRF52 that has the radio turned off. Are both nRF52832s going to run the same firmware or is the one with the Radio of going to run another firmware? Not that it really matters, since in both cases you will have to forward the firmware received over the air to the serial interface.

[Felipe Ribas]

Understood. Yes, their firmwares are originally different. So the idea would be to transmit the update to the one with radio ON and this would forward via serial interface to the other one so it can update itself. So it's possible? I just have to boot different bootloaders and it should work?

[bjorn-spockeli]

Yes, that should be possible to implement, however, you will have to modify the existing BLE bootloader to forward the received packets to the serial interface instead of updating itself. The serial bootloader should not need any modifications.