I have spent the last couple of days researching and understanding GATT to control my new adjustable bed which I can currently only control via Manufacturer's app but I want to control via my smart home setup.
I am able to get characteristics which are read and write with/without response so I know I am on right track and I have used PacketLogger on OSX to get values which I now know are acceptable when sent by myself using an IOS app called BLE Scanner which just asks for a Hex or Text Value to send to the characteristics for the device (bed) and I have sent the values I extracted from PacketLogger when using the manufacturer's app (5212 006E 0100 4EBD) as Hex separately and it vibrates the bed!
I just need to be able to this myself now with Noble by sending either straight to the peripheral.writeHandle function or via the characteristic.write function. I have tried many different things but I don't get the same effect as BLE Scanner app when it sends the values individually as Hex so I know the device isn't happy with what i'm sending. I noticed there is some padding added for what I think is L2CAP but as I say BLE Scanner just works for (5212 006E 0100 4EBD) as long as they are sent separately as Hex.
Would really appreciate some help to get me over the line.
I have tried so far to write to the characteristic and also tried direct to the periphel as there is no mention of the characteristic UUID in the PacketLogger logs when writing via BLE Scanner whereas when using the Manaufacturer app PacketLogger shows the write characteristic UUID so both I think will work. I have tried many variations of
peripheral.writeHandle(18, Buffer.from("5212006E01004EBD", "hex"),
true, function(err) { console.log('writehandle'+err) });
and
characteristic.write(Buffer.from("5212006E01004EBD", "hex"), true,
function (error) {
if (!error) {
console.log("write succesful");
} else {
console.log("write unsuccesful");
}
}.bind(this));
I do see a difference in the ATT Send PacketLogger entry for the BLE Scanner App which works and my attempt in Noble which doesn't work - Write Request - Handle:0x0012 - Value: 5212 006E 0100 4EBD Opcode is 0x0012 is the working packetlogger entry for BLE Scanner whereas my attempt shows multiple entries for each attempt and the first entry is always Exchange MTU Request - MTU: 104 and the Opcode is 0x0002. No matter what I change in Noble the Opcode remains the same.
