DFU timeouts when slowing down connection interval

[PF-JohnF]

I am working on slowing down the connection interval in the secure_bootloader_ble example to reduce the average power usage. I've successfully slowed the interval down to 1 rx/tx every 1 second, but if I increase the min_conn_interval any further the DFU operation through NRF Connect BLE will fail due to a timeout about 20% to 40% of the way through the OTA DFU. Specifically, the error log says: "DFU failed with error: When writing 'CREATE' command to Control Point Characteristic of DFU Target: Characteristic value write failed: Could not get characteristic with id [DEVICE MAC].0.7.13"

My sdk_config.h has the following differences from the default:

#define NRF_DFU_BLE_MIN_CONN_INTERVAL 1200
...
#define NRF_DFU_BLE_MAX_CONN_INTERVAL 3200
...
#define NRF_DFU_BLE_CONN_SUP_TIMEOUT_MS 30000
...
#define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 80

nrf_dfu_ble.c:

#define APP_ADV_INTERVAL    MSEC_TO_UNITES(1600, UNIT_0_625_MS)

Otherwise, all other defines/configuration are the same, and no other code has been modified.

I believe NRF_DFU_BLE_MAX_CONN_INTERVAL and NRF_DFU_BLE_CONN_SUP_TIMEOUT_MS are near if not at their max values.

I am using soft device 132 version 6.0.0, and using SEGGER studio as the SDK.

I'm thinking I may be missing a configuration on the BLE device side. It's also possible that the NRF Connect BLE's timeout parameter is set to a maximum, in which case I'd be interested in increasing the timeout period.

Thanks in advance.

[Einar Thorsrud]

Hi,

I see the same on my end. Testing on nRF Connect for iOS this works, so there seems like there is an issue with the nRF Connect for desktop BLE app. I have created an internal bug report. I cannot say when it will be fixed, though.

[PF-JohnF]

I think I've found a solution, but I'm not sure if it will effect other pieces of the code.

Inside adapter.js, https://nordicsemiconductor.github.io/pc-ble-driver-js/adapter.js.html

Function _shortWriteWithoutResponse has a constant timeout time of 2 seconds on line 3833. Once I increased this to 4 seconds I stopped getting errors. I was getting timeout errors before as well, so this seemed like the fix. Is there anyway this could be set to be user configurable in the NRF Connect program? Having to go into the app.asar file's JS feels somewhat hacky.

[Einar Thorsrud]

Hi,

Thank you for the update, I am glad to hear you found the issue.

I have forwarded your request for a configurable timeout to the responsible development team so that they can look into it and consider it for a future release.