Interfacing with Python
Introduction
In this tutorial you will learn how to programmatically communicate with the Tmote Sky using the Python programming language. This will enable you to do such things as process data from your mote in real-time. In addition, you can send commands or data back to the mote to impact its operation. The possibilities are endless.
Setup
This tutorial was written and tested using the following:
- Contiki 2.7
- Python 2.7.3 (and pySerial)
- Ubuntu 12.04
- Tmote Sky
Connect the Tmote Sky to your computer using a USB cable and install the Sky Shell example. See the @Sky Shell@ tutorial for instructions on how to do this. We use this example so that we’ll have data to ensure that we are correctly reading and writing to the mote.
Step 1
Create a Python file called serial.py containing the following code:
#!/usr/bin/python
import serial
ser = serial.Serial(
port='/dev/ttyUSB0',\
baudrate=115200,\
parity=serial.PARITY_NONE,\
stopbits=serial.STOPBITS_ONE,\
bytesize=serial.EIGHTBITS,\
timeout=0)
print("connected to: " + ser.portstr)
ser.write("help\n");
while True:
line = ser.readline();
if line:
print(line),
ser.close()
Note: This code assumes the mote you are using for this tutorial is connected to /dev/ttyUSB0. Please check this using the make motelist command as shown in the figure below. If the mote you are using is connected to a different device file, please modify the Python code accordingly.
Step 2
Run the Python code using the command:
python serial.py
You should see output similar to the following:
connected to: /dev/ttyUSB0 Available commands: ?: shows this help binprint: print binary data in decimal format blink [num]: blink LEDs ([num] times) collect: collect data from the network collect-view-data: sensor data, power consumption, network stats echo <text>: print <text> energy: print energy profile exit: exit shell hd: print binary data in hexadecimal format help: shows this help kill <command>: stop a specific command killall: stop all running commands mac <onoroff>: turn MAC protocol on (1) or off (0) netcmd <command>: run a command on all nodes in the network nodeid: set node ID null: discard input packetize: put data into one packet power: print power profile powerconv: convert power profile to human readable output powertrace [interval]: turn powertracing on or off, with reporting interval <interval> quit: exit shell randwait <maxtime> <command>: wait for a random time before running a command reboot: reboot the system repeat <num>
