How comunicate with UART Transparent service BLE in xamarin - xamarin.forms

Question

I'm trying to do an app with xamarin which can communicate with a chip rn4870. This BLE chip uses UART Transparent services. I'm new with bluetooth, so the most thing I read for do a communication with a ble device is to scan the device, connect it, looking for the service you want, get the characteristics and write,read or notify.
But, The most example I read, with heart rate device o smarthwath, the service is defined , for example a service for a battery, so, I can get the service, then the characteristic and read it. But with UART Transparent service, I get the 49535343-FE7D-4AE5-8FA9-9FAFD205E455 service to datatransfer, and then I get TX 49535343-1E4D-4BD9-BA61-23C647249616 and RX 49535343-8841-43F4-A8D4-ECBE34729BB3 characteristic but I don't know how to communicate.
Also I'm using plugin BLE of xamarin, with these plugin I can not see any particular function or documentation where I can use client/server functionality.
https://github.com/xabre/xamarin-bluetooth-le
So, if anyone has a idea how or which step I have to follow to can communicate with it and if you know how I could do it with xamarin, I will appreciate.
Thanks in advance.

Answer 1

You can handle the UART transparent service the same way you would handle a battery service.
Scan for available devices, even better if you use a filter to only find devices offering the UART service
adapter.DeviceDiscovered += (s,a) => deviceList.Add(a.Device);
await adapter.StartScanningForDevicesAsync(new[] { Guid.Parse("49535343-FE7D-4AE5-8FA9-9FAFD205E455"));
Connect to the device
try
{
await _adapter.ConnectToDeviceAsync(device);
}
catch(DeviceConnectionException e)
{
// ... could not connect to device
}
Get the UART service and both of the characteristics
var TX = await connectedDevice.GetServiceAsync(Guid.Parse("49535343-1E4D-4BD9-BA61-23C647249616"));
var RX = await connectedDevice.GetServiceAsync(Guid.Parse("49535343-8841-43F4-A8D4-ECBE34729BB3"));
Enable notifications on the TX characteristic to receive the answers and start writing to the RX characteristic
TX.ValueUpdated += (o, args) =>
{
// Do something with the received value
var bytes = args.Characteristic.Value;
};
await TX.StartUpdatesAsync();
await RX.WriteAsync(bytes);
If you want to test the connection and the communication procedure you can use a generic BLE scanner app such as nRF Connect. Use it to search for your device and you can read, write and activate notifications with it.
There is also a sample app using your xamarin plugin that offers this functionality:
check the ble status
discover devices
connect/disconnect
discover the services
discover the characteristics
see characteristic details
read/write and register for notifications of a characteristic