examples: added more elaborated Python UART example

Closes #376.

Signed-off-by: Alex Tereschenko <alext.mkrs@gmail.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

examples/python/uart_receiver.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 
-# Author: Brendan Le Foll <brendan.le.foll@intel.com>
+# Author: Alex Tereschenko <alext.mkrs@gmail.com>
-# Copyright (c) 2015 Intel Corporation.
+# Copyright (c) 2015 Alex Tereschenko
 #
 # Permission is hereby granted, free of charge, to any person obtaining
 # a copy of this software and associated documentation files (the
@@ -24,5 +24,21 @@
 
 import mraa
 
+# Initialize UART
 u=mraa.Uart(0)
-print u.getDevicePath()
+
+# Set UART parameters
+u.setBaudRate(115200)
+u.setMode(8, mraa.UART_PARITY_NONE, 1)
+u.setFlowcontrol(False, False)
+
+# Start a neverending loop waiting for data to arrive.
+# Press Ctrl+C to get out of it.
+while True:
+  if u.dataAvailable():
+    # We are doing 1-byte reads here
+    data_byte = u.readStr(1)
+    print(data_byte)
+    # Just a two-way half-duplex communication example, "X" is a flag
+    if data_byte == "X":
+      u.writeStr("Yes, master!")

examples/python/uart_sender.py

@@ -0,0 +1,57 @@
+#!/usr/bin/env python
+
+# Author: Alex Tereschenko <alext.mkrs@gmail.com>
+# Copyright (c) 2015 Alex Tereschenko
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE
+
+import mraa
+import sys
+
+sys.stdout.write("Initializing UART...")
+u=mraa.Uart(0)
+print("...done")
+
+print("Setting UART parameters: baudrate 115200, 8N1, no flow control")
+u.setBaudRate(115200)
+u.setMode(8, mraa.UART_PARITY_NONE, 1)
+u.setFlowcontrol(False, False)
+
+msg_b = bytearray("Hello, mraa byte array!", "ascii")
+print("Sending message as a byte array: '{0}'".format(msg_b))
+u.write(msg_b)
+# Make sure the message gets out to the line.
+# It's generally unnecessary (and performance-degrading) to do this explicitly,
+# UART driver normally takes care of that, but it may be useful with specific
+# half-duplex endpoints, like Dynamixel servos.
+u.flush()
+
+msg_s = "Hello, mraa string!"
+print("Sending message as a string: '{0}'".format(msg_s))
+u.writeStr(msg_s)
+
+sys.stdout.write("Two-way, half-duplex communication, sending a flag...")
+u.writeStr("X")
+print("...sent, awaiting response...")
+# Checking for data in the RX buffer, giving it a 100ms timeout
+if u.dataAvailable(100):
+  print("We've got a response: '{0}', says the other side".format(u.readStr(20)))
+else:
+  print("No data received, do you have anything at the other end?")