PA/LNA in bootloader

[Zhenya Zh]

Hello.

I have pa/lna on my device. It works properly in application (rssi is about 30 dbm). But when application goes into bootloader (dfu over ble using nrfconnect on android) rssi is about 95-100 dbm. 

I tried to add pa/lna init to secure_bootloader code. And when i download this on erased chip, I see that rssi is about 20-30 in bootloader mode. But function sd_ble_opt_set() return 1. And when I download the application and start dfu, the application goes into bootloader mode and the signal level becomes 100 again.

Why it happens?

[Einar Thorsrud]

Hi,

I assume the PA/LNA is controlled by GPIO pins using the PA/LNA support in the SoftDevice? Essentially this is just the SoftDevice asserting selected GPIO pins when there is radioactivity, so it is no different than controlling any other GPIO pins. It should be the same in the bootloader and application, but it has to be configured in both since the SoftDevice is initialized separately in the bootloader and application. Have you checked with a logic analyzer to see if the GPIO pins are controlled as expected? How do you configure the PA/LAN control in the SoftDevice and application?

[Zhenya Zh]

I fix this problem by adding pa/lna init at ble_dfu_transport_init() fucntion in nrf_dfu_ble.c after ble_stack_init(). 

But I do not think this is a good solution. How to solve this?

[Einar Thorsrud]

Hi,

I am sorry for the late reply.

I am glad to hear you got it working. Why is it not a good idea to do the PA/LNA configuration in ble_dfu_transport_init()? I would say that is exactly where you should put it in the bootloader since that is where the SoftDevice (BLE stack) is initialized.

[Zhenya Zh]

Hi,

I think it is not a good idea beacause i need to modify sdk. Can I do it in my *.c files?

[Einar Thorsrud]

Hi,

I see your point, but I do not see a good way to do this without modifying the DFU library code. The reason is that there is no sensible way to put this in the example bootloader project since it has to be done after the SoftDevice is initialized. (It wold be tempting to implement the nrf_dfu_init_user() function and put it there, but this will not work since it is called before nrf_dfu_init(), which is when the transport is initialized).

[Zhenya Zh]

Thank you.