USB Serial Kotlin - kotlin

Question

I am looking for an Android USB-Serial example in Kotlin.
Almost every example I have found is in Java, which I suppose is still ok, but I haven't been able to compile any of them successfully.
I am quite new to Android / Kotlin, and just want to get the most basic send and receive going from my phone to a USB device over an OTG cable.
Any help / pointers / suggestions gratefully received.
Thank you
Garrett

Answer 1

I was able to dig up some old code to reference for this. I don't guarantee any of it, but in combination with your Java based libraries, this should be a start, and then combining with reference from: https://github.com/mik3y/usb-serial-for-android
One thing I recall being a massive problem, was we had to have the app as a system level app. Which was either by installing it in a specific directory and checking the "System App" permission.
class SerialPort(private val serialPort: Any) {
private val serialPortR: Class<*> = Class.forName("android.hardware.SerialPort")
fun read(buffer: ByteBuffer): Int {
val read = serialPortR.getMethod("read", ByteBuffer::class.java)
return read.invoke(this, buffer) as Int
}
fun write(buffer: ByteBuffer, len: Int) {
val write = serialPortR.getMethod("write", ByteBuffer::class.java, Int::class.java)
write.invoke(this, buffer, len)
}
fun close() {
val close = serialPortR.getMethod("close")
close.invoke(this)
}
}
class SerialManager private constructor(private val serialService: Any) {
private val serialManager: Class<*> = Class.forName("android.hardware.SerialManager")
fun openSerialPort(port: String, baudRate: Int): SerialPort = reflectSerialPort(port, baudRate)
private fun reflectSerialPort(port: String, baudRate: Int): SerialPort {
serialManager.cast(this)
val openSerialPort = serialManager.getMethod("openSerialPort", String::class.java, Int::class.java)
return SerialPort(openSerialPort.invoke(serialManager, port, baudRate))
}
companion object {
fun get(c: Context): SerialManager {
val serialService = getSerialService(c)
return SerialManager(serialService)
}
#SuppressLint("WrongConstant")
private fun getSerialService(c: Context) = c.getSystemService("serial") ?: throw Exception("No Serial Service")
}
}