Hi Adam, On Mon, Mar 21, 2022 at 4:03 PM Adam Pigg <adam@xxxxxxxxxxx> wrote: > > Hi > > A bit of background, I write a linux desktop/mobile app called > Amazfish which interfaces with several watches over BLE using their > GATT services. To do this, I use the bluez dbus api (technically a > thin wrapper around it I wrote called qble > https://github.com/piggz/qble) > > All has been good so far, I support several generations of > Huami/Amazfit watches, as well as the open source Pinetime and > Bangle.js. For the Amazfit watches, i have implementations for older > devies such as the Bip, and newer ones such as the GTS. > > Much of the reverse engineering comes from the Android Gadget Bridge > project, which supports many more devices. > > My community of users donated to buy me a newer device called a GTR2, > which, according to the GB devs uses the same protocol as the slightly > older GTS, and the packet captures I have from Android would support > this. > > But this is where my trouble starts with Bluez, my existing > implementation doesnt work at all. Normally, after a connection, I > would wait for the ServicesResolved signal, which happens pretty fast > on all other devices, but on the GTR2, it takes about 30 seconds, by > which time, the watch has disconnected. (i get a disconnected signal > immediately after the ServicesResolved signal) > > To rule out my code, I have tried several things: > Gatttool > With gattool, i can connect, get the services, enable a notification, > write a value and get the expected results seemingly fine > > Python-gatt (using the bluez dbus api) > Im unable to iterate the services, like my app, it takes 30 seconds to > get the signal and then swiftly disconnects > > Gattlib (https://github.com/labapart/gattlib) > Gattlib is interesting as it appears to have "borrowed" much of its > code directly from bluez. When built against the system bluez, if the > version is > 5.42, it will use the dbus api. When I do this, again im > unable to list services on the watch. However, if I edit the build to > force it to use its internal gatt implementation, which appears to be > the same one used by gatttool, then, it IS able to interrogate the > watch. > > I have attached 3 files > 1. test python program which should print services, and associated btmon > 2. btmon output while using gatttool > 3. btmon output running gattlib discover example > > Note, other than discovery, I havnt been able to get gattlib to > read/write/notify! > > It seems as though I may be triggering a bug in the bluez dbus api? > Can anyone suggest anything? What version are you using? I would first try with the latest to see if that something already fixed. -- Luiz Augusto von Dentz
