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Unable to connect to our product from one particular phone

Hi

After doing a rebuild of a previously working project, my personal phone and a test phone is unable to connect to our product.

The device is discovered by the phone without a problem, but always times out when trying to connect. This happens from our app and from nRF Connect:

nRF Connect, 2020-02-08
Nordic_HRM (FD:B1:75:DE:F5:1A)
D    22:33:32.630    gatt.close()
D    22:33:32.632    wait(200)
V    22:33:32.834    Connecting to FD:B1:75:DE:F5:1A...
D    22:33:32.834    gatt = device.connectGatt(autoConnect = false, TRANSPORT_LE, preferred PHY = LE 1M)
D    22:34:02.844    [Callback] Connection state changed with status: 133 and new state: DISCONNECTED (0)
E    22:34:02.844    Error 133 (0x85): GATT ERROR
I    22:34:02.844    Disconnected

I have used the nrf sniffer with Wireshark, and I can't see a single packet from my phone when it is trying to connect to the device. The phone can connect to the previous version of our firmware on our device and on the PCA10040 kits. It work from other phones.

If I use the unmodified ble_app_hrs examples on a PCA10040, I get the same behaviour. I can't connect from my phone, but it work from other phones.

I honestly have no idea what can be wrong, and I have spent a lot of time to try to understand this.

Does anybody have a clue? It is hard to say that there is something wrong with the Nordic stuff since it works on other phones, at the same time it is strange that my phone should be picky about this particular build since old builds and other devices with just fine with it. Is there anything I can reset to shake this out?

Environment

My phone is a Google Pixel (G-2PW4100) running Android 10.

The test phone is an 3 year old Samsung phone, running something older than Android 10.

I'm building the firmware with SES 4.40, I'm not quite sure which version we used to build the original firmware with.

The original firmware is built with SDK 15.0.0 and we used the same for our DFU build.

Parents
  • Hi Trygve

    I'm sorry, but without seeing the more detailed sniffer side of things it's hard to say why the GATT NOT FOUND error occurs. The GATT request is nothing out of the ordinary, as 517 the default value Android phones request when updating MTU if I'm not mistaken. As this is just a request, the nRF52832 will reply by updating the MTU to as much as it can handle, being 247, which is reflected in the MTU changed to: 247 messages.

    Best regards,

    Simon

Reply
  • Hi Trygve

    I'm sorry, but without seeing the more detailed sniffer side of things it's hard to say why the GATT NOT FOUND error occurs. The GATT request is nothing out of the ordinary, as 517 the default value Android phones request when updating MTU if I'm not mistaken. As this is just a request, the nRF52832 will reply by updating the MTU to as much as it can handle, being 247, which is reflected in the MTU changed to: 247 messages.

    Best regards,

    Simon

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