I developed a tiny webserver on Python. Its aim is to translate an URL's parameters (such as http://192.168.0.17:6066/?rly=7&status=1&port=ttyUSB0) in an command (here RLY71) and write it on a serial port (here /dev/ttyUSB0), where the Arduino is connected.
Here is the WebServer code (many many "print" for debugging purpose) :
__author__ = 'deadbird'
import time
import BaseHTTPServer
from urlparse import urlparse, parse_qs
import serial
from time import sleep
HOST_NAME = '192.168.0.17'
PORT_NUMBER = 6066
class MyHandler(BaseHTTPServer.BaseHTTPRequestHandler):
def do_HEAD(s):
s.send_response(200)
s.send_header("Content-type", "text/html")
s.end_headers()
def do_GET(s):
port = -1
status = -1
rly = -1
"""Respond to a GET request."""
s.send_response(200)
s.send_header("Content-type", "text/html")
s.end_headers()
s.wfile.write("<html><head><title>Piscine</title></head>")
parameters = parse_qs(urlparse(s.path).query)
if parameters.has_key('rly'):
rly = parameters['rly'][0]
if parameters.has_key('status'):
status = parameters['status'][0]
if parameters.has_key('port'):
port = parameters['port'][0]
if port != -1 and status !=-1 and rly !=-1:
#ser = serial.Serial("/dev/ttyUSB0")
#ser.write("RLY11\n")
#ser.close()
try:
print "All parameters ok, sending command\n"
print "Opening port: {0}".format(port)
ser = serial.Serial("/dev/{0}".format(port), 9600, timeout=1)
print "Opened port \'{0}\'".format(ser.name)
if ser.isOpen():
print "Port successfully opened"
print "isWritable = {0}".format(ser.writable())
else:
print "Cannot open port :("
command = "RLY{0}{1}".format(rly, status)
print "Command = \'{0}\'".format(command)
print "Writing command on serial port"
written = ser.write("RLY{0}{1}\n".format(rly, status))
print "Bytes written = {0}".format(written)
print "Reading result"
ret = ser.readline()
if len(ret) == 0:
s.wfile.write("NOTHING DONE")
else:
print ret
s.wfile.write(ret)
ser.flushOutput()
ser.flushInput()
ser.close()
except (serial.SerialException, serial.SerialTimeoutException) as e:
s.wfile.write(e)
s.wfile.write("</body></html>")
if __name__ == '__main__':
server_class = BaseHTTPServer.HTTPServer
httpd = server_class((HOST_NAME, PORT_NUMBER), MyHandler)
print time.asctime(), "Server Starts - %s:%s" % (HOST_NAME, PORT_NUMBER)
try:
httpd.serve_forever()
except KeyboardInterrupt:
pass
httpd.server_close()
print time.asctime(), "Server Stops - %s:%s" % (HOST_NAME, PORT_NUMBER)
This work perfectly on a Mac with PySerial installed. When I run the very same script on a RaspberryPi, nothing happens. For example, when I use the URL http://192.168.0.17:6066/?rly=7&status=1&port=ttyUSB0, the result on the console is the following:
192.168.0.16 - - [19/Apr/2014 20:59:28] "GET /?rly=7&status=1&port=ttyUSB0 HTTP/1.1" 200 -
All parameters ok, sending command
Opening port: ttyUSB0
Opened port '/dev/ttyUSB0'
Port successfully opened
isWritable = True
Command = 'RLY71'
Writing command on serial port
Bytes written = 6
Reading result
192.168.0.16 - - [19/Apr/2014 20:59:30] "GET /favicon.ico HTTP/1.1" 200 -
I tried chmown-ing the port to user "pi", chmod-ing it to 777, nothing changes.
I ran some more tests. I wrote this stripped down version if the script:
import serial
ser = serial.Serial("/dev/ttyUSB0")
ser.write("RLY11\n")
ser.close()
When I run it as a .py file, is fails. But when I run it from a command-line using python interactive shell (ie: line per line), it works! I have absolutely no idea of what to do, can someone help?
