So we start with the Python this time:
#!/usr/bin/python2.7
from time import sleep
import serial
from serial.tools import list_ports
if __name__ == "__main__":
ports = [port[0] for port in list_ports.comports()]
print "Using serial port %s" % (ports[-1])
serial = serial.Serial(ports[-1],baudrate=9600, timeout=0, writeTimeout=1)
serial.flushInput()
serial.flushOutput()
while True:
content = serial.readline() # Read the newest output from the Arduino
if content:
print content
sleep(.1) # Delay for one tenth of a second
Now when I run this program it will wait for a message and if there is anything write it out.
Now we can add to the sketch:
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
// Set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);
String oldContent; //Keep this between usb reads();
void setup(){
pinMode(7, INPUT_PULLUP); //Set pin 7 to INPUT_PULLUP, this uses the inbuilt resistor on the pin
lcd.begin();
Serial.begin(9600); // USB is always 12 Mbit/sec
oldContent=""; //Initialise this variable
}
void loop(){
String content = getString(); //Get the USB content
checkButton(); //Check for a result
//If there was USB content display it
if (content != ""){
content.concat(" "); //Add another character
oldContent = content;//Save the content
}
//If there is something to display
if (oldContent!=""){
displayMessage(oldContent); //show me!
}else{
//Otherwise check again soon!
delay(250);
}
}
String getString(){
String content = ""; //Set up return variable
char character; //char to read from USB
while(Serial.available()) { //While there is more to read, do more
character = Serial.read(); //Read the char
content.concat(character); //Add it to the return variable
delay (10); //make sure we don't act too quickly and assume it's over before it really is
}
Serial.print(content); //Echo back the content heard on USB
return content;
}
void displayMessage(String message){
if (message!=""){ //Make sure there is something to show
lcd.home(); //Start at row 1
printRows(message,0); //print the message, possibly on 2 rows
delay(2500); //Show the first screen for a while, give people a change to read
for (int posCounter = 0; posCounter < message.length(); posCounter++){ //For all of the chars
checkButton();
printRows(message,posCounter); //print the message, possibly on 2 rows
delay(600);
}
delay(600);
}
}
void printRows(String message, int pos){
lcd.clear();//Clear the screen again
lcd.setCursor(0,0);
lcd.print(message.substring(pos,pos+16));
if (message.length() >16){
lcd.setCursor(0, 1); //Set to the second row
lcd.print(message.substring(pos+16,pos+32));
}
}
// a little check for a button
void checkButton(){
if (digitalRead(7) == LOW ) {
Serial.print("button pressed");
}
}
There are two new bits here. First we echo back what we heard on USB after it was received. Second we have a couple of checks for a button on pin 7. I turned this into a function so I can add the check in more places as there are quite a few loops that could miss the event.
This function would allow me to break out of my loops if the button was pressed if I returned true instead of just printing.
Not a major development but now with the two python programs I can dynamically update my message and listen to my device for anything happening locally.
Next goal is to have a "service" react to the button and trigger something happen like get a REST service response to display a message on the LCD, baby steps :)
Here's a picture of a cat:
