Develop Reference

read data from serialport

I am new to C# and programming in general.
I am trying to communicate with a ohmmeter which is conneted via usb to my computer.
I am able to configurate the device and even recieve data.
But i can not acces this data. I can just print it on to the console.
(Was inspired by the code on the microsoft site)
Here is the constructer of my "communication"-class where i configurate the port:
public SCPI_Commands()
{
_SerialPort.PortName = SetPortName(_SerialPort.PortName);
_SerialPort.BaudRate = 115200;
_SerialPort.Parity = Parity.None;
_SerialPort.DataBits = 8;
_SerialPort.StopBits = StopBits.One;
_SerialPort.Handshake = Handshake.None;
_SerialPort.ReadTimeout = 500;
_SerialPort.WriteTimeout = 500;
_SerialPort.Open();
_SerialPort.DataReceived += _serialPort_DataReceived;
}
Here is my function which sends a query to the device (The constant Measurment_Value represents a scpi command which is understood by my ohmmeter) :
public void get_measurement()
{
_SerialPort.WriteLine(Measurment_Value);
}
And here is the private function which checks if the device is sending data and printing it on the console (not sure how this function works) :
private void _serialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
Console.WriteLine(_SerialPort.ReadLine());
}
Unfortunately i am not able to return the data as a string. My goal is to do some calculations with the received data.
Does someone has any ideas ?
Greetings from Germany.
Luke

You can read from buffer to temp byte array and then get it as string, see the below example. Put this in _serialPort_DataReceived
// this the read buffer
byte[] buff = new byte[9600];
int readByteCount = _serialPort.BaseStream.Read(buff, 0, _serialPort.BytesToRead);
// you can specify other encodings, or use default
string response = System.Text.Encoding.UTF8.GetString(buff);
Side Note
If you want to keep your sanity while working with SerialPort, always send and receive as byte array. Then, get the equivalent string using Encoding.

How to write data to USB HID device in Android with only a single input endpoint

I have a USB HID device that I would like to communicate with. I am successfully doing so on Windows using the HidSharp library (link: https://github.com/treehopper-electronics/HIDSharp). My Windows application is developed using the .NET Framework 4.5, C#, and Visual Studio.
I now want to communicate with this same USB HID device from an Android tablet instead of from the Windows desktop. I am encountering some problems doing so. When I have the device plugged in to my tablet, it reports a single interface with a single "read" endpoint. Here is what is reported to me:
Interface #0
Class: Human Interaction Device (0x3)
Endpoint: #0
Address : 0x81 (10000001)
Number : 1
Direction : Inbound (0x80)
Type : Intrrupt (0x3)
Poll Interval : 1
Max Packet Size: 64
Attributes : 000000011
As you can see, it only reports a single endpoint, which is an inbound endpoint. I need to be able to output simple commands to this device, which I was able to do so successfully on Windows using HidSharp.
HidSharp abstracted everything into a single "stream" object that you could read from and write to. Using the Android APIs, there isn't a single "stream" object, but rather there seem to be 3 different ways of reading/writing: bulk transfer, control transfer, and USB Request. I've tried sending out data using all 3, but with seemingly no success.
Any suggestions on what to do? Is there a reason why I could send out data to this device on Windows, but seemingly cannot do so from Android? Is there a way to use a single endpoint as both a read and a write endpoint? Is there something that I am just obviously missing and not understanding?
I am using Xamarin as my development environment (C#, Visual Studio 2017). Since code is always helpful, here is how I am connecting to the device:
int VendorID = 0x04d8;
int ProductID = 0x2742;
UsbManager USB_Manager = null;
UsbDevice USB_Device = null;
UsbDeviceConnection DeviceConnection = null;
UsbInterface DeviceInterface = null;
UsbEndpoint OutputEndpoint = null;
UsbEndpoint InputEndpoint = null;
//Grab the Android USB manager and get a list of connected devices
var USB_Manager = MyMainActivity.ApplicationContext.GetSystemService(Android.Content.Context.UsbService) as Android.Hardware.Usb.UsbManager;
var attached_devices = USB_Manager.DeviceList;
//Find the device in the list of connected devices
foreach (var d in attached_devices.Keys)
{
if (attached_devices[d].VendorId == VendorID && attached_devices[d].ProductId == ProductID)
{
USB_Device = attached_devices[d];
break;
}
}
//Assuming we found the correct device, let's set everything up
if (USB_Device != null)
{
for (int j = 0; j < USB_Device.InterfaceCount; j++)
{
DeviceInterface = USB_Device.GetInterface(j);
for (int i = 0; i < DeviceInterface.EndpointCount; i++)
{
var temp_ep = DeviceInterface.GetEndpoint(i);
if (temp_ep.Type == Android.Hardware.Usb.UsbAddressing.XferInterrupt)
{
if (temp_ep.Direction == Android.Hardware.Usb.UsbAddressing.In)
{
InputEndpoint = temp_ep;
}
if (temp_ep.Direction == Android.Hardware.Usb.UsbAddressing.Out)
{
OutputEndpoint = temp_ep;
}
}
}
}
//Request permission to communicate with this USB device
UsbReceiver receiver = new UsbReceiver();
PendingIntent pending_intent = PendingIntent.GetBroadcast(Game.Activity, 0, new Android.Content.Intent(UsbReceiver.ACTION_USB_PERMISSION), 0);
IntentFilter intent_filter = new IntentFilter(UsbReceiver.ACTION_USB_PERMISSION);
Game.Activity.RegisterReceiver(receiver, intent_filter);
USB_Manager.RequestPermission(USB_Device, pending_intent);
bool has_permission = USB_Manager.HasPermission(USB_Device);
var device_connection = USB_Manager.OpenDevice(USB_Device);
device_connection.ClaimInterface(DeviceInterface, true);
DeviceConnection = device_connection;
}
Next, here is how I attempt to read from the device:
//3 methods of attempting to read from the device
//Method 1:
byte[] inpt = new byte[64];
var request = new UsbRequest();
request.Initialize(DeviceConnection, InputEndpoint);
var byte_buffer = ByteBuffer.Allocate(64);
request.Queue(byte_buffer, 64);
DeviceConnection.RequestWait();
byte_buffer.Rewind();
for(int i = 0; i < 64; i++)
{
inpt[i] = (byte) byte_buffer.Get();
}
//Method 2:
byte[] inpt = new byte[64];
DeviceConnection.BulkTransfer(InputEndpoint, inpt, inpt.Length, 1000);
//Method 3:
byte[] inpt = new byte[64];
DeviceConnection.ControlTransfer(UsbAddressing.In, 0, 0, 0, inpt, 64, 1000);
And finally, here is how I attempt to write data to this device:
//Method 1:
byte[] output_msg; //This variable is assigned elsewhere in the code
DeviceConnection.BulkTransfer(OutputEndpoint, output_msg, output_msg.Length, 30);
//Method 2:
byte[] output_msg; //This variable is assigned elsewhere in the code
DeviceConnection.ControlTransfer(UsbAddressing.Out, 0, 0, 0, output_msg, output_msg.Length, 1000);
//Method 3:
byte[] output_msg; //This variable is assigned elsewhere in the code
var write_request = new UsbRequest();
write_request.Initialize(DeviceConnection, OutputEndpoint);
var byte_buffer_write = ByteBuffer.Wrap(output_msg);
request.Queue(byte_buffer_write, output_msg.Length);
DeviceConnection.RequestWait();
"OutputEndpoint" is typically null because there is no output endpoint, so I often replace "OutputEndpoint" with "InputEndpoint", but with no success.
Any help would be greatly appreciated! Thanks!!!

You are dealing with HID devices which means you should do Interrupt Transfers.
In Android, you should use UsbRequest to perform Interrupt Transfers (as it does Asynchronous NonBlocking IO).
The endpoints are unidirectional and can be used for both inbounds and outbound (but not at the same time)
If the endpoint is inbound then submit the Urb using UsbRequest and queue as you tried before but using empty buffer with expected bufferLength.
The RequestWait will return UsbRequest Object back upon completion.
If the usbRequest.getEndPoint().getDirection() is inbound then your buffer variable will be updated with read buffer from the device.
If the usbRequest.getEndpoint().getDirection() is outbound then you should pass your buffer to write data to the device

Bluetooth C# using 32feet.net to connect to a speaker

I am currently trying use 32feet.net to connect to a bluetooth speaker that once shutdown (the computer or the speaker) they stay paired but they dont auto reconnect. Therefore I want to make an windows service that tries to reconnect to it every so often if its not connected and if it can find it.
I have tried
C# 32feet.Net: Handling two bluetooth connections in seperate threads, gives SocketException
Code but for some reason there is a few things that light up red.
I am also trying to figure out and make this code work at the same time for the same purpose
public void btconnect()
{
List<Device> devices = new List<Device>();
InTheHand.Net.Sockets.BluetoothClient bc = new InTheHand.Net.Sockets.BluetoothClient();
InTheHand.Net.Sockets.BluetoothDeviceInfo[] array = bc.DiscoverDevices();
int count = array.Length;
for (int i = 0; i<count; i++)
{
Device device = new Device(array[i]);
devices.Add(device);
}
foreach(Device d in devices)
{
if (d.DeviceInfo.ToString().Equals("myphonesdevicenumber"))
{
Guid MyServiceUuid
= new Guid("{00112233-4455-6677-8899-aabbccddeeff}"); // found this somewhere not sure what the string represents.
byte[] guidbytearray = d.DeviceInfo.ToByteArray(); // guid as a byte array.
string guidstring = d.DeviceInfo.ToString(); //guid as a string.
Int64 guid64 = d.DeviceInfo.ToInt64(); // guid as an int64.
Guid g = new Guid(guidbytearray);
bc.Connect(d.DeviceInfo,MyServiceUuid);
// turnoff = false;
}
}
}
List devices = new List();
in the orignal code this wasnt there and I dont know if he was using (Device) it from a external reference or not.

In the article of 32feet, they list an inner-class named Device. You should use it in your program.
The Guid is the identifier for the socket used to connect to your BT device.
The format is a 32 digit long of hex numbers divided into group of 8, 4 ,4 ,4 and 12. Between the groups there is a '-'.

Bluetooth api for surface pro 3 windows 8.1

I have a bluetooth button from Radius networks. The builtin - "add a bluetooth device" finds it every time.
I need the api or a stack that I can use to do from my app. I am doing this in c#. the library 32 feet is not compatible

To enumerate RFCOMM Bluetooth devices attached to a device, do:
var DEVICE_ID = new Guid("{00000000-0000-0000-0000-000000000000}"); //Enter your device's RFCOMM service id (try to find it on manufactorer's website
var services = await Windows.Devices.Enumeration.DeviceInformation.FindAllAsync(
RfcommDeviceService.GetDeviceSelector(
RfcommServiceId.FromUuid(DEVICE_ID)));
To connect to a the first available device, do:
if (services.Count > 0)
{
var service = await RfcommDeviceService.FromIdAsync(services[0].Id);
//Open a socket to the bluetooth device for communication. Use the socket to communicate using the device's API
var socket = new StreamSocket();
await socket.ConnectAsync(service.ConnectionHostName, service.ConnectionServiceName, SocketProtectionLevel
.BluetoothEncryptionAllowNullAuthentication); //Substitue real BluetoothEncryption
}
To send data to the device and read data back, do:
var BYTE_NUM = 64 as UInt32; //Read this many bytes
IInputStream input = socket.InputStream;
IOutputStream output = socket.OutputStream;
var inputBuffer = new Buffer();
var operation = input.ReadAsync(inputBuffer, BYTE_NUM, InputStreamOptions.none);
while (!operation.Completed) Thread.Sleep(200);
inputBuffer = operation.GetResults();
var resultReader = DataReader.FromBuffer(inputBuffer);
byte[] result = new byte[BYTE_NUM];
resultReader.ReadBytes(result);
resultReader.Dispose();
//Do something with the bytes retrieved. If the Bluetooth device has an api, it will likely specify what bytes will be sent from the device
//Now time to give some data to the device
byte[] outputData = Encoding.ASCII.GetBytes("Hello, Bluetooth Device. Here's some data! LALALALALA");
IBuffer outputBuffer = outputData.AsBuffer(); //Neat method, remember to include System.Runtime.InteropServices.WindowsRuntime
operation = output.WriteAsync(outputBuffer);
while (!operation.Completed) Thread.Sleep(200);
await output.FlushAsync(); //Now the data has really been written
This will work for all RFCOMM (normal) bluetooth devices, if your device uses Bluetooth Low Energy please use the corresponding GATT classes.

Unable to read from Serial Port using C# Mono (RaspberryPi)

I'm attempting to write a C# library which looks at all available USB serial ports on a Raspberry Pi so that I can enumerate, identify and communicate with a set of Arduinos connected to the Pi via a USB hub.
I am able to make this work on my windows machine (several Arduinos connected to my desktop computer) and have even been able to make it work on my Pi however, I am struggling to understand how to generalize the fix.
If I attempt to run the program by itself on the Pi, I am able to open the serial port and send data however, I cannot receive anything from the Arduinos: I get timeout exceptions. I understand that Mono's implementation of SerialPort is limited and I must use SerialPort.ReadByte() instead of Readline() and the data received events (my solution is based on code from HowToSystemIOPorts). My Serial port enumeration is using a method outlined in another stack exchange response here.
My timeout is currently set to 4 seconds, which is several orders of magnitude longer than I expect to receive the message.
After a lot of googling, I came across mention of using minicom to initialize the serial port here, which to my surprise allowed me to receive data from the Arduino. The biggest drawback is that I need to initialize the port using minicom and leave the process opening each time I boot the Pi. I also can't seem to figure out how to make this work with multiple Arduinos.
Here is what I have tried so far:
Updated the Pi firmware and software to their latest versions
Attempted to use both an Arduino MEGA 2560 R3 and Arduino UNO
Changed the owner of the tty* ports (ttyACM0 and ttyUSB0 in this case) to both my user and group
Successfully configured the port via minicom, left the process running and start the program and read/wrote data. A manual process which only seems to work for one Arduino at a time
Successfully run the program in Windows without fault
Verified the Arduinos are recognized by the Pi running "dmesg | grep tty"
Here is what I hope to solve:
Automatic setup/initialization of the Arduino serial ports. Whether through a shell script run before the main program or within Mono code so that the code below can run as intended.
Here is my connection code:
public bool StartArduinoComms()
{
string[] ports = GetPortNames();
foreach (string port in ports)
{
mLogger.LogMessage(ProsthesisCore.Utility.Logger.LoggerChannels.Arduino, string.Format("Found serial port {0}", port));
}
bool foundCorrectArduino = false;
var idPacket = new ArduinoMessageBase();
idPacket.ID = ArduinoMessageValues.kIdentifyValue;
string jsonOutput = Newtonsoft.Json.JsonConvert.SerializeObject(idPacket);
foreach (string port in ports)
{
SerialPort serialPort = new SerialPort(port, kArduinoCommsBaudRate);
serialPort.Parity = Parity.None;
serialPort.DataBits = 8;
serialPort.StopBits = StopBits.One;
//Only check unopened ports
if (!serialPort.IsOpen)
{
serialPort.Open();
//Disable telemtry just incase
var toggle = new { ID = ArduinoMessageValues.kTelemetryEnableValue, EN = false };
string disableTelem = Newtonsoft.Json.JsonConvert.SerializeObject(toggle);
serialPort.Write(disableTelem);
//Discard any built up data
serialPort.DiscardInBuffer();
serialPort.Write(jsonOutput);
serialPort.ReadTimeout = kIDTimeoutMilliseconds;
string response = string.Empty;
for (int i = 0; i < kNumRetries; ++i)
{
try
{
//This is guaranteed to timeout if not configured through minicom
response = ReadLine(serialPort);
break;
}
//Catch case where the serial port is unavailable. MOve to next port
catch (TimeoutException)
{
continue;
}
}
if (!string.IsNullOrEmpty(response))
{
//Perform response validation
}
else
{
//Got no response
}
if (!foundCorrectArduino)
{
serialPort.Close();
}
}
}
return foundCorrectArduino;
}
/// <summary>
/// From https://stackoverflow.com/questions/434494/serial-port-rs232-in-mono-for-multiple-platforms
/// </summary>
/// <returns></returns>
private static string[] GetPortNames()
{
int p = (int)Environment.OSVersion.Platform;
List<string> serial_ports = new List<string>();
// Are we on Unix?
if (p == 4 || p == 128 || p == 6)
{
string[] ttys = System.IO.Directory.GetFiles("/dev/", "tty*");
foreach (string dev in ttys)
{
//Arduino MEGAs show up as ttyACM due to their different USB<->RS232 chips
if (dev.StartsWith("/dev/ttyS") || dev.StartsWith("/dev/ttyUSB") || dev.StartsWith("/dev/ttyACM"))
{
serial_ports.Add(dev);
}
}
}
else
{
serial_ports.AddRange(SerialPort.GetPortNames());
}
return serial_ports.ToArray();
}

Have a look at stty command. It will let you set/read teminal settings
http://linux.about.com/od/lna_guide/a/gdelna38t01.htm will give a rundown on it's use.
It would be easier to call out to than minicom, and the settings stay on the device.

I have done something like the same as you before.
I had to read and write data through USB Serial adapter, and didnt use minicom.
It may not be god code but i found that inorder to read the data I could create a new thread and have that check for data, my code include a lot of stuff but basicly i did this:
System.Threading.Thread newThread;
newThread = new System.Threading.Thread(this.check_get_data);
and the check_get_data method
public void check_get_data ()
{
byte tmpByte = 0;
while (m_objSerialPort.BytesToRead != 0) {
tmpByte = (byte)m_objSerialPort.ReadByte ();
DoSomethingWithByte(tmpByte);
Thread.Sleep(20);
}
}
this is currently running with two usbserials. dont know if it helps but hope you find your solution