spi: bit bang via UART in Scala

Author: schoeberl

src/main/scala/spi/SerialSpiTest.scala

@@ -7,26 +7,80 @@ class SerialSpiTest {
 }
 
 object SerialSpiTest extends App {
+
+  def writeRead(s: String): String = {
+    for (c <- s) {
+      out.write(c.toByte)
+    }
+    // println("Wrote: " + s)
+    val buf = new Array[Byte](1)
+    var ret = ""
+    var stop = false
+    while (!stop) {
+      if (port.bytesAvailable() > 0) {
+        port.readBytes(buf, 1)
+        val c = buf(0).toChar
+        ret = ret + c
+        stop = c == '\n'
+      }
+    }
+    // print("Received: " + ret)
+    Thread.sleep(300)
+    ret
+  }
+
+  def writeByte(v: Int) = {
+    for (i <- 0 until 8) {
+      val bits = ((v >> (7-i)) & 1) << 1
+      // clock off, set data
+      writeRead(s"w44$bits\r")
+      // clock on, keep data
+      writeRead(s"w44${bits + 1}\r")
+    }
+    // not now, writeRead("w440\r") // clock off
+  }
+
+  def readByte() = {
+    var v = 0
+    for (i <- 0 until 8) {
+      writeRead("w440\r") // clock off
+      // data changes after neg edge
+      writeRead("w441\r") // clock on
+      // sample on pos edge
+      val rx = writeRead("r")
+      // println("received: " + rx(8))
+      // '8' is bit set
+      val bit = if (rx(8) == '8') 1 else 0
+      v = (v << 1) | bit
+    }
+    writeRead("w440\r") // clock off (maybe?), does not heart on multibyte read
+    v
+  }
+
+  def readAdx(cmd: Int): Int = {
+    writeRead("w444\r")
+    writeRead("w440\r")
+    writeByte(cmd)
+    writeByte(0)
+    val ret = readByte()
+    writeRead("w444\r")
+    ret
+  }
+
   // TODO: fix this hard coded thing
   val port = SerialPort.getCommPort("/dev/tty.usbserial-210292B408601")
   port.openPort()
   port.setBaudRate(115200)
   // port.setComPortTimeouts(SerialPort.TIMEOUT_READ_SEMI_BLOCKING, 0, 0)
   port.setComPortTimeouts(SerialPort.TIMEOUT_NONBLOCKING, 0, 0)
   val out = port.getOutputStream
-  val buf = new Array[Byte](1)
-  val s = "Hello World"
-  for (i <- 0 until 10) {
-    val v = s(i)
-    out.write(v)
-    Thread.sleep(100)
-    println(s"Wrote ${v.toChar}")
-    if (port.bytesAvailable() != 0) {
-      println(s"Bytes available: ${port.bytesAvailable()}")
-      val cnt = port.readBytes(buf, 1)
-      println("read: " + cnt + " " + (buf(0).toChar))
-    }
-  }
+
+  print(writeRead("w444\r"))
+  print(writeRead("w440\r"))
+  print(writeRead("r"))
+  val v = readAdx(0x0b) // dev id
+  println("device id is 0x" + v.toHexString)
+  writeRead("w444\r")
   out.close()
   port.closePort()
 }