Recently, I am trying to make sort of "light control" on Arduino. I use Raspberry Pi to send the control message via serial port (USB cable).Here is the Arduino code :
int redled = 12; int whiteled = 48; void setup() { Serial.begin(9600); pinMode(redled,OUTPUT); pinMode(whiteled,OUTPUT); } void loop() { if(Serial.available()) { char cmd = Serial.read(); switch(cmd) { case'r': digitalWrite(redled,HIGH); delay(2000); digitalWrite(redled,LOW); break; case'w': digitalWrite(whiteled,HIGH); delay(2000); digitalWrite(whiteled,LOW); break; } } else { Serial.println("hello pi"); delay(1000); } } After that, I used pySerial from Python interpreter to control the pins, and everything was working fine. Here is a piece of interpreter output:
Python 2.7.3 (default, Mar 18 2014, 05:13:23) [GCC 4.6.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import serial >>> ser = serial.Serial('/dev/ttyACM0',9600) >>> x = ser.read(10) >>> print 'x = ',x x = hellhello >>> ser.write('w') #white led turn on and off 1 >>> ser.close() >>> Everything worked fine and led did turn on and off, so I decided to write a simple Python script to do the same:
import serial import time ser = serial.Serial('/dev/ttyACM0',9600) x = ser.read(10) print 'x = ',x time.sleep(2) ser.write('w') ser.close() The following is the execution command and result:
pi@raspberrypi ~ $ python serialtest.py x = helello pi It only appeared the string from Arduino, but no led turn on at all. It looks like everything should be fine, so I don't know what the problem can be. I already search some articles and add "time.sleep(2)" before "ser.write()", but it still couldn't work.I would appreciate any help, many thanks in advance!
UPDATE : I made the controller send me back the data it was receiving and it looks like it isn't receiving anything when I am running the script, but receives everything when I send the data from the interpreter. The code of the arduino code now looks like this:
int redled = 12; int whiteled = 48; void setup() { Serial.begin(9600); pinMode(redled,OUTPUT); pinMode(whiteled,OUTPUT); } void loop() { if(Serial.available()) { char cmd = Serial.read(); switch(cmd) { case'r': digitalWrite(redled,HIGH); delay(2000); digitalWrite(redled,LOW); Serial.println("Cmd received"); break; case'w': digitalWrite(whiteled,HIGH); delay(2000); digitalWrite(whiteled,LOW); Serial.println("Cmd received"); break; } } }