nrf52840 Dongle giving 0x3D reason on Disconnect after a while.

RE: nrf52840 Dongle giving 0x3D reason on Disconnect after a while.

Simonr — Fri, 25 Nov 2022 07:37:17 GMT

Please note that if you erase the full flash on an nRF52840 Dongle you will need to do some soldering to reflash the the DFU bootloader that lets you flash projects directly to the Dongle (see the "Recover after an accidental UICR erase" section in our Dongle Programming tutorial for details.)

But in order to erase and program your nRF52840 Dongle using the Programmer app, you should be able to detect it as an Open DFU Bootloader when choosing your device. Please note that it must be in the Bootloader mode (press the side mounted button next to the white one while it is powered to enter the bootloader mode.

Best regards,

Simon

RE: nrf52840 Dongle giving 0x3D reason on Disconnect after a while.

noob_123 — Thu, 24 Nov 2022 11:59:49 GMT

I can erase all the Flash from nrf52833 using nRF Connect Programmer but how to fully erase nrf52840 dongle?

RE: nrf52840 Dongle giving 0x3D reason on Disconnect after a while.

Simonr — Thu, 24 Nov 2022 09:04:12 GMT

Try deleting the bonding information on the nRF52833 peripheral as well in case that is the device that is keeping this "old" information hindering the Dongle from connecting correctly to it. You can also try doing a full erase using the nRF Connect Programmer application for example.

Best regards,

Simon

RE: nrf52840 Dongle giving 0x3D reason on Disconnect after a while.

noob_123 — Wed, 23 Nov 2022 14:10:26 GMT

I updated the Firmware on both devices but still it is showing the same behavior with particular dongle. But if I change the dongle everything works fine.
What else then updating the firmware can resolve this issue?

RE: nrf52840 Dongle giving 0x3D reason on Disconnect after a while.

Simonr — Wed, 23 Nov 2022 14:06:40 GMT

Disconnect reason 0x3D means that a message failed a Message Integrity Check (MIC) which means the other end is required to disconnect by the specification, as the connection is no longer secure. This should only happen when the key used for encryption is wrong, and my guess is that you connected and bonded once, then perhaps erased the bonding information on either of the sides before trying to connect again with the old bonding info, which might result in an error like this as the wrong encryption will be returned from the side with no bonding information.

I think you should be able to get the device back up and running if you make sure bonding information on both devices is deleted, then connect and pair again. This was also reported just a few days ago, but there the issue was a phone having trouble with Bluetooth connections in some WiFi states.

Best regards,

Simon