Difference between revisions of "Interfacing with Python"

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Create a Python file called serial.py containing the following code:
 
Create a Python file called serial.py containing the following code:
<syntaxhighlight lang="python">
+
<source lang="python">
 
#!/usr/bin/python
 
#!/usr/bin/python
 
import serial
 
import serial
Line 35: Line 35:
 
print(line),
 
print(line),
 
ser.close()
 
ser.close()
</syntaxhighlight>
+
</source>
  
 
Note:  
 
Note:  
Line 47: Line 47:
 
Run the Python code using the command:
 
Run the Python code using the command:
  
python serial.py
+
  python serial.py
 +
 
 +
If you encounter any errors, see the following link for troubleshooting - http://anrg.usc.edu/contiki/index.php/Troubleshooting
  
 
You should see output similar to the following:
 
You should see output similar to the following:
connected to: /dev/ttyUSB0
+
  connected to: /dev/ttyUSB0
Available commands:
+
  Available commands:
?: shows this help
+
  ?: shows this help
binprint: print binary data in decimal format
+
  binprint: print binary data in decimal format
blink [num]: blink LEDs ([num] times)
+
  blink [num]: blink LEDs ([num] times)
collect: collect data from the network
+
  collect: collect data from the network
collect-view-data: sensor data, power consumption, network stats
+
  collect-view-data: sensor data, power consumption, network stats
echo <text>: print <text>
+
  echo <text>: print <text>
energy: print energy profile
+
  energy: print energy profile
exit: exit shell
+
  exit: exit shell
hd: print binary data in hexadecimal format
+
  hd: print binary data in hexadecimal format
help: shows this help
+
  help: shows this help
kill <command>: stop a specific command
+
  kill <command>: stop a specific command
killall: stop all running commands
+
  killall: stop all running commands
mac <onoroff>: turn MAC protocol on (1) or off (0)
+
  mac <onoroff>: turn MAC protocol on (1) or off (0)
netcmd <command>: run a command on all nodes in the network
+
  netcmd <command>: run a command on all nodes in the network
nodeid: set node ID
+
  nodeid: set node ID
null: discard input
+
  null: discard input
packetize: put data into one packet
+
  packetize: put data into one packet
power: print power profile
+
  power: print power profile
powerconv: convert power profile to human readable output
+
  powerconv: convert power profile to human readable output
powertrace [interval]: turn powertracing on or off, with reporting interval <interval>
+
  powertrace [interval]: turn powertracing on or off, with reporting interval <interval>
quit: exit shell
+
  quit: exit shell
randwait <maxtime> <command>: wait for a random time before running a command
+
  randwait <maxtime> <command>: wait for a random time before running a command
reboot: reboot the system
+
  reboot: reboot the system
repeat <num> <time> <command>: run a command every <time> seconds
+
  repeat <num> <time> <command>: run a command every <time> seconds
rfchannel <channel>: change CC2420 radio channel (11 - 26)
+
  rfchannel <channel>: change CC2420 radio channel (11 - 26)
routes: dump route list in binary format
+
  routes: dump route list in binary format
send <rexmits>: send data to the collector node, with rexmits hop-by-hop retransmissions
+
  send <rexmits>: send data to the collector node, with rexmits hop-by-hop retransmissions
sense: print out sensor data
+
  sense: print out sensor data
senseconv: convert 'sense' data to human readable format
+
  senseconv: convert 'sense' data to human readable format
size: print the size of the input
+
  size: print the size of the input
time [seconds]: output time in binary format, or set time in seconds since 1970
+
  time [seconds]: output time in binary format, or set time in seconds since 1970
timestamp: prepend a timestamp to data
+
  timestamp: prepend a timestamp to data
txpower <power>: change CC2420 transmission power (0 - 31)
+
  txpower <power>: change CC2420 transmission power (0 - 31)
5.0: Contiki>
+
  5.0: Contiki>
  
 
== Understanding the Code ==
 
== Understanding the Code ==
  
<syntaxhighlight lang="python">
+
<source lang="python">
 
  import serial
 
  import serial
</syntaxhighlight>
+
</source>
  
 
The first line will include the module for the serial port API. This API is provided by pySerial.
 
The first line will include the module for the serial port API. This API is provided by pySerial.
  
<syntaxhighlight lang="python">
+
<source lang="python">
 
ser = serial.Serial(
 
ser = serial.Serial(
 
     port='/dev/ttyUSB0',\
 
     port='/dev/ttyUSB0',\
Line 103: Line 105:
 
     bytesize=serial.EIGHTBITS,\
 
     bytesize=serial.EIGHTBITS,\
 
     timeout=0)
 
     timeout=0)
</syntaxhighlight>
+
</source>
  
 
This next line instantiates an object with the appropriate serial port configuration for communication with the Sky mote. The necessary settings are shown in the table below.
 
This next line instantiates an object with the appropriate serial port configuration for communication with the Sky mote. The necessary settings are shown in the table below.
Line 119: Line 121:
 
|}
 
|}
  
<syntaxhighlight lang="python">
+
<source lang="python">
 
  print("connected to: " + ser.portstr)
 
  print("connected to: " + ser.portstr)
</syntaxhighlight>
+
</soource>
  
 
The print statement is simply a sanity check. It just reminds us which port we are connected to.
 
The print statement is simply a sanity check. It just reminds us which port we are connected to.
  
<syntaxhighlight lang="python">
+
<source lang="python">
 
  ser.write("help\n");
 
  ser.write("help\n");
</syntaxhighlight>
+
</source>
  
 
This line demonstrates how data can be written to the serial port. In this example we send the command "help" to the Sky Shell so that it will send back the list of shell commands it supports.
 
This line demonstrates how data can be written to the serial port. In this example we send the command "help" to the Sky Shell so that it will send back the list of shell commands it supports.
  
<syntaxhighlight lang="python">
+
<source lang="python">
 
while True:
 
while True:
 
     line = ser.readline();
 
     line = ser.readline();
 
     if line:
 
     if line:
 
print(line)
 
print(line)
</syntaxhighlight >
+
</source>
  
 
Here, we read data from the serial port indefinitely and print it out, one line at a time. Note that in this case, ''line'' will typically end with a newline.
 
Here, we read data from the serial port indefinitely and print it out, one line at a time. Note that in this case, ''line'' will typically end with a newline.
Line 142: Line 144:
 
To terminate the program, you can use Ctrl + C to send an interrupt signal.
 
To terminate the program, you can use Ctrl + C to send an interrupt signal.
  
<syntaxhighlight lang="python">
+
<source lang="python">
 
  ser.close()
 
  ser.close()
</syntaxhighlight>
+
</source>
  
 
This last line never actually gets executed but it shows how the serial resource can be freed.
 
This last line never actually gets executed but it shows how the serial resource can be freed.
 
  
  
 
[[Contiki_tutorials | Back to Contiki Tutorials]]
 
[[Contiki_tutorials | Back to Contiki Tutorials]]

Latest revision as of 19:06, 27 September 2016

Back to Contiki Tutorials

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.


Sample output of make motelist

Step 2

Run the Python code using the command:

 python serial.py

If you encounter any errors, see the following link for troubleshooting - http://anrg.usc.edu/contiki/index.php/Troubleshooting

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> 

Understanding the Code

 import serial

The first line will include the module for the serial port API. This API is provided by pySerial.

ser = serial.Serial(
    port='/dev/ttyUSB0',\
    baudrate=115200,\
    parity=serial.PARITY_NONE,\
    stopbits=serial.STOPBITS_ONE,\
    bytesize=serial.EIGHTBITS,\
    timeout=0)

This next line instantiates an object with the appropriate serial port configuration for communication with the Sky mote. The necessary settings are shown in the table below.

Serial Configuration
Baud rate 115200
Data bits 8
Parity None
Stop bits 1
 print("connected to: " + ser.portstr)
</soource>

The print statement is simply a sanity check. It just reminds us which port we are connected to.

<source lang="python">
 ser.write("help\n");

This line demonstrates how data can be written to the serial port. In this example we send the command "help" to the Sky Shell so that it will send back the list of shell commands it supports.

while True:
     line = ser.readline();
     if line:
	print(line)

Here, we read data from the serial port indefinitely and print it out, one line at a time. Note that in this case, line will typically end with a newline.

To terminate the program, you can use Ctrl + C to send an interrupt signal.

 ser.close()

This last line never actually gets executed but it shows how the serial resource can be freed.


Back to Contiki Tutorials