blink.ino

/* Blink.ino */

int pin;
int state;

void do_serial_read ( void );
int  read_number    ( char * );

void setup ( void ) {
  Serial.begin(9600);
  pin = 13;
  state = 0;
}

void loop ( void ) {
  Serial.println("Hello, Pi!");
  if (Serial.available()) {
    do_serial_read();

    Serial.print("Updating state of pin ");
    Serial.print(pin);
    Serial.print(" to state ");
    Serial.print(state);
    Serial.println(".");

    digitalWrite(pin, state);
  }
}

void do_serial_read ( void ) {
  Serial.println("Trying to read arguments");
  char *pin_str, *stt_str;
  int arg_ind, chr_ind;
  char in;

  pin_str = (char *) malloc(4 * sizeof(char));
  stt_str = (char *) malloc(4 * sizeof(char));
  Serial.println("Memory allocated!");

  pin_str[3] = '\0';
  stt_str[3] = '\0';
  arg_ind = 0;

  while (Serial.available() > 0) {
    Serial.println("Reading character.");
    if (chr_ind > 3) {
      Serial.println("Unable to parse :: input too long!");
      return;
    }
    in = Serial.read();
    if (in == ':') {
      arg_ind = 1;
      chr_ind = 0;
      Serial.println("Switching to second argument");
    } else {
      (arg_ind ? pin_str : stt_str)[chr_ind++] = in;
    }
  }
  Serial.println("Arguments read.");

  pin   = read_number(pin_str);
  state = read_number(stt_str);

  free(pin_str);
  free(stt_str);
}

int read_number (char *str) {
  Serial.println("Parsing.");
  int n, pt;
  n = 0;
  for(pt = 0; str[pt] != '\0'; pt++) {
    Serial.println("Parsed character");
    n += str[pt] - '0';
  }
  return n;
}

/* Local Variables: */
/* mode: c */
/* End: */

blink.py

# Blink.py

import sys

pin, state = sys.argv[1], sys.argv[2]

def immediate(s):
    print s
    sys.stdout.flush()

try:
    int(pin)
    int(state)
except:
    print('Your numbers are bad and you should feel bad.')
    exit()

immediate('Importing Serial library...')
import serial
immediate('Done.')

immediate('Opening connection to Arduino...')
tty = '/dev/ttyACM0'
arduino = serial.Serial(tty, 9600)
immediate('Connection established.')

to_arduino = '{}:{}'.format(pin, state)
immediate('Writing command `{}` to Arduino on {}...'.format(to_arduino, tty))
arduino.write(to_arduino)

immediate('Command sent.  Waiting for response...')

while True:
    print ' > ', arduino.readline()

immediate('Closing connection Arduino...')
arduino.close()
immediate('Done')

gist

https://gist.github.com/7969727