Add tools/pyboard.py, a simple module to communicate with the pyboard.

Using pyboard.py you can use Python running on your PC to execute
commands on the connected pyboard.  See examples in that file.

tools/pyboard.py

@@ -0,0 +1,127 @@
+"""
+pyboard interface
+
+This module provides the Pyboard class, used to communicate with and
+control the pyboard over a serial USB connection.
+
+Example usage:
+
+    import pyboard
+    pyb = pyboard.Pyboard('/dev/ttyACM0')
+    pyb.enter_raw_repl()
+    pyb.exec('pyb.Led(1).on()')
+    pyb.exit_raw_repl()
+
+"""
+
+import time
+import serial
+
+class Pyboard:
+    def __init__(self, serial_device):
+        self.serial = serial.Serial(serial_device)
+
+    def close(self):
+        self.serial.close()
+
+    def enter_raw_repl(self):
+        self.serial.write(b'\r\x01') # ctrl-A: enter raw REPL
+        self.serial.write(b'\x04') # ctrl-D: soft reset
+        data = self.serial.read(1)
+        while self.serial.inWaiting() > 0:
+            data = data + self.serial.read(self.serial.inWaiting())
+            time.sleep(0.1)
+        if not data.endswith(b'raw REPL; CTRL-B to exit\r\n>'):
+            print(data)
+            raise Exception('could not enter raw repl')
+
+    def exit_raw_repl(self):
+        self.serial.write(b'\r\x02') # ctrl-B: enter friendly REPL
+
+    def eval(self, expression):
+        ret = self.exec('print({})'.format(expression))
+        ret = ret.strip()
+        return ret
+
+    def exec(self, command):
+        command_bytes = bytes(command, encoding='ascii')
+        for i in range(0, len(command_bytes), 10):
+            self.serial.write(command_bytes[i:min(i+10, len(command_bytes))])
+            time.sleep(0.01)
+        self.serial.write(b'\x04')
+        data = self.serial.read(2)
+        if data != b'OK':
+            raise Exception('could not exec command')
+        data = self.serial.read(2)
+        while self.serial.inWaiting() > 0:
+            data = data + self.serial.read(self.serial.inWaiting())
+            time.sleep(0.1)
+        if not data.endswith(b'\x04>'):
+            print(data)
+            raise Exception('could not exec command')
+        if data.startswith(b'Traceback') or data.startswith(b'  File '):
+            print(data)
+            raise Exception('command failed')
+        return data[:-2]
+
+    def get_time(self):
+        t = str(self.exec('pyb.time()'), encoding='ascii').strip().split()[1].split(':')
+        return int(t[0]) * 3600 + int(t[1]) * 60 + int(t[2])
+
+def run_test():
+    device = '/dev/ttyACM0'
+    pyb = Pyboard(device)
+    pyb.enter_raw_repl()
+    print('opened device {}'.format(device))
+
+    print('seconds since boot:', pyb.get_time())
+
+    pyb.exec('def apply(l, f):\r\n for item in l:\r\n  f(item)\r\n')
+
+    pyb.exec('leds=[pyb.Led(l) for l in range(1, 5)]')
+    pyb.exec('apply(leds, lambda l:l.off())')
+
+    ## USR switch test
+
+    if True:
+        for i in range(2):
+            print("press USR button")
+            pyb.exec('while pyb.switch(): pyb.delay(10)')
+            pyb.exec('while not pyb.switch(): pyb.delay(10)')
+
+        print('USR switch passed')
+
+    ## accel test
+
+    if True:
+        print("hold level")
+        pyb.exec('accel = pyb.Accel()')
+        pyb.exec('while abs(accel.x()) > 10 or abs(accel.y()) > 10: pyb.delay(10)')
+
+        print("tilt left")
+        pyb.exec('while accel.x() > -10: pyb.delay(10)')
+        pyb.exec('leds[0].on()')
+
+        print("tilt forward")
+        pyb.exec('while accel.y() < 10: pyb.delay(10)')
+        pyb.exec('leds[1].on()')
+
+        print("tilt right")
+        pyb.exec('while accel.x() < 10: pyb.delay(10)')
+        pyb.exec('leds[2].on()')
+
+        print("tilt backward")
+        pyb.exec('while accel.y() > -10: pyb.delay(10)')
+        pyb.exec('leds[3].on()')
+
+        print('accel passed')
+
+    print('seconds since boot:', pyb.get_time())
+
+    pyb.exec('apply(leds, lambda l:l.off())')
+
+    pyb.exit_raw_repl()
+    pyb.close()
+
+if __name__ == "__main__":
+    run_test()