Read/write properties over BLE with gatttool

[seppe]

Hello @emathieu, welcome to the Decawave forum.

You can have a look at the Python script made by my colleague that uses the gatttool (through the pygatt wrapper).

@emathieu

I can’t write anything. When I try, gatttool hangs forever, the blue LED remains ON, and I have to kill the application to end it. Maybe I do something wrong, are there some working examples of writing properties ?

Could you clarify what exactly you are trying to write and what version of Bluez you are using? Note that Bluez 4 has some known (but badly documented) issues when using LE devices.

Also note that the BLE API is only designed to work with the LEAPS app, so there are some weird quirks. One of these quirks is that the device auto-disconnects after a couple of seconds of BLE inactivity. It could be the device disconnects before you are able to read/write the characteristics you are interested in. I suggest subscribing to notifications as soon as youare connected to prevent disconnects.

@emathieu

On the other hand, the property I’m interesed in is the Persisted Position, in Anchor mode. The documentation specifies that it is write-only, but doing some tests with the Android application on 2 phones, it seems that is can also be read. During all my tests, it happened once that I could read the actual stored value (which was the right one), but it never occured again. Is there something to be done to read/write this property ?

You are right, this property seems to be read/write. I think this might be a mistake in the documentation.