nRF52 DK running ble_app_uart_c disconnects 6 seconds after connecting to peripheral error code: 0x08

[EricDelangis]

We have an nRF52 DK system running ble_app_uart_c example code and communicating with a peripheral device.  We setup a second development system using another nRF52 DK system running the exact same code as the first system but after about 6 seconds after a connection we get a timeout error 0x08 and it disconnects.  

I've tried changing the clock accuracy settings as you describe above but no effect. 

<info> app: Connected to device with Nordic UART Service.

<info> app: Disconnected.

<info> app: Disconnected. conn_handle: 0x0, reason: 0x8

<info> app: Connecting to target 520822071920

<info> app: ATT MTU exchange completed.

<info> app: Ble NUS max data length set to 0x14(20)

<info> app: Discovery complete.

<info> app: Connected to device with Nordic UART Service.

<info> app: Disconnected.

<info> app: Disconnected. conn_handle: 0x0, reason: 0x8

<info> app: Connecting to target 520822071920

<info> app: ATT MTU exchange completed.

<info> app: Ble NUS max data length set to 0x14(20)

<info> app: Discovery complete.

<info> app: Connected to device with Nordic UART Service.

<info> app: Disconnected.

<info> app: Disconnected. conn_handle: 0x0, reason: 0x8

You can see from the debug window that we are stuck in this loop.

We are also running the exact same development configuration on both systems:

SDK 15.3

Segger SES V 4.10

nRF DK PCA 10040

Please advise.

[Simonr]

Hi Eric

You're right of course, the ble_app_uart_c examples don't include bonding from scratch, but you can modify the example to do so if you'd like. My bad that I initially jumped to that conclusion.

Can you tell me more about your peripheral devices? Are they DKs as well, and are they running an example code or custom code? Are the two/three peripherals the same devices as one another. Also, please update me on the status of the third set up as well as the memory erase.

Best regards,

Simon

[EricDelangis]

Hi Simon,

The peripheral devices (all three) are made for us by a company that uses the Minew MS50SFA which is a BLE module that uses the nRF52810 chip.  The module has it's own clock source but I can't get any additional information on the module other than it uses the ble_app_uart example code unmodified.  I'm thinking that module (peripheral) is working fine because I can communicate with it using Minew's own UART app on an Android phone as well as your nRF Connect on Android.  So the problem seems to point to the DK.  I am waiting for another engineer to get the third development system up and running.  However, I did test the third peripheral device with my development system and have the same problem.

[EricDelangis]

Update!

Hi Simon,

I programmed a new Minew MS50SFA BLE module with the ble_app_uart (peripheral example) and was able to connect, and stay connected, to the DK running the ble_app_uart_c (central example) code.  So, now it seems clear that the problem is actually caused by code in the peripheral device that is causing the connection to drop.  Although, it is not clear yet why the peripheral device disconnects from the DK but not nRF Connect or Minew's own UART app. More to come...

[EricDelangis]

Solution:  The peripheral device was disconnecting when it received invalid response string.  The "echo" feature was enabled which caused an invalid response string to be sent.  Solution was to disable "echo" in central device and to have the manufacturer of the peripheral device to ignore invalid responses and disconnect only after a minute or two timeout of invalid responses.