Exception on connection with nRF52 as connectivity chip

[gkovelman]

I'm using the pc-nrfutil v3.3.2 executable on Windows 10 which is using the ble driver v0.11.3. Connectivity chip is NRF52 on PCA10040. I'm trying to perform secure buttonless DFU on my custom board.

The error that I'm seeing is:

x:\nrfutil\bin>nrfutil_332.exe -v dfu ble -pkg "pkg.zip" -ic NRF52 -p COM37 -n xxx -f Shared library: C:\Users\Me\AppData\Local\Temp_MEI31~1\lib\win\x86_32\pc_ble_driver_shared_sd_api_v3.dll Swig module name: pc_ble_driver_sd_api_v3 Board already flashed with connectivity firmware. Using connectivity board at serial port: COM37 Sending Application image.

BLE: ble_enable with local ATT MTU: 247 BLE: Scanning for xxx Received advertisement report, address: 0x705681D2C705, device_name: Received advertisement report, address: 0x705681D2C705, device_name: Received advertisement report, address: 0xD7D7784BF5B7, device_name: Received advertisement report, address: 0xD7D7784BF5B7, device_name: xxx BLE: Found target advertiser, address: 0xD7D7784BF5B7, name: xxx BLE: Connecting to 0xD7D7784BF5B7 Received advertisement report, address: 0xDCA904951E08, device_name: Received advertisement report, address: 0xD7D7784BF5B7, device_name: BLE: Found target advertiser, address: 0xD7D7784BF5B7, name: BLE: Connecting to 0xD7D7784BF5B7 Received advertisement report, address: 0xD7D7784BF5B7, device_name: xxx BLE: Found target advertiser, address: 0xD7D7784BF5B7, name: xxx BLE: Connecting to 0xD7D7784BF5B7 Received advertisement report, address: 0x4F351FA8E874, device_name: Received advertisement report, address: 0x4F351FA8E874, device_name: BLE: Connected to [215L, 215L, 120L, 75L, 245L, 183L] ATT MTU exchanged: conn_handle=0 att_mtu=247 Successfully Connected BLE: Service Discovery Traceback (most recent call last): File "nordicsemi__main.py", line 871, in File "site-packages\click\core.py", line 722, in call File "site-packages\click\core.py", line 697, in main File "site-packages\click\core.py", line 1066, in invoke File "site-packages\click\core.py", line 1066, in invoke File "site-packages\click\core.py", line 895, in invoke File "site-packages\click\core.py", line 535, in invoke File "nordicsemi\main.py", line 747, in ble File "nordicsemi\dfu\dfu.py", line 122, in dfu_send_images File "nordicsemi\dfu\dfu.py", line 83, in _dfu_send_image File "nordicsemi\dfu\dfu_transport_ble.py", line 453, in open File "nordicsemi\dfu\dfu_transport_ble.py", line 147, in connect File "site-packages\pc_ble_driver_py\ble_driver.py", line 124, in wrapper File "site-packages\pc_ble_driver_py\ble_adapter.py", line 196, in service_discovery TypeError: 'NoneType' object has no attribute 'getitem' Failed to execute script main__

Secure buttonless DFU is working with the iOS/Android apps/libraries, so my BLE profile is compatible. This is also working correctly when the connectivity chip is nRF51 on PCA10031. Log is the following:

x:\nrfutil\bin>nrfutil_332.exe -v dfu ble -pkg "pkg.zip" -ic NRF51 -p COM38 -n xxx -f Shared library: C:\Users\Me\AppData\Local\Temp_MEI14~2\lib\win\x86_32\pc_ble_driver_shared_sd_api_v2.dll Swig module name: pc_ble_driver_sd_api_v2 Flashing connectivity firmware... Connectivity firmware flashed. Using connectivity board at serial port: COM38 Sending Application image. BLE: Scanning for xxx Received advertisement report, address: 0xDCA904889157, device_name: Received advertisement report, address: 0xD7D7784BF5B7, device_name: Received advertisement report, address: 0xD7D7784BF5B7, device_name: xxx BLE: Found target advertiser, address: 0xD7D7784BF5B7, name: xxx BLE: Connecting to 0xD7D7784BF5B7 Received advertisement report, address: 0xDCA904889157, device_name: Received advertisement report, address: 0xDCA904889157, device_name: Received advertisement report, address: 0x479528C8E156, device_name: BLE: Connected to [215L, 215L, 120L, 75L, 245L, 183L] Successfully Connected BLE: Service Discovery Bonded Buttonless characteristic discovered -> Bond etc...

[bihanssen]

Hi, with ATT_MTU=247 it might be that the data is being sent to the bootloader too fast, we have seen this happen before. Could you try to reduce the MTU and see if that helps?

The pca10031 runs a softdevice that does not support MTU above 23, so that might explain why the problem is not occuring there.

[gkovelman]

So fast that the service discovery fails, even before the data transmission? Weird.

I'll try to reproduce this with ATT MTU=23

[bihanssen]

You're probably right, the error happens too fast for the MTU to be the issue here, unless in some indirect way.

[gkovelman]

Confirming that reducing the MTU helps with the issue. I modified to #define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 23 and the PCA10040 could perform DFU. Can we expect support for larger ATT MTU?

[bihanssen]

Related to https://github.com/NordicSemiconductor/pc-nrfutil/issues/147 To be looked into.