Writing on LCD Display using Python and Arduino. Requires pyfirmata module.

lcd.py

from pyfirmata import Arduino, util, STRING_DATA
board = Arduino('COM6')
board.send_sysex( STRING_DATA, util.str_to_two_byte_iter('Hello!') )

def msg( text ):
    if text:
        board.send_sysex( STRING_DATA, util.str_to_two_byte_iter( text ) )

lcdFirmata.ino

#include <LiquidCrystal.h>
#include <Firmata.h>

LiquidCrystal lcd(9, 8, 5, 4, 3, 2);
int lastLine = 1;

void stringDataCallback(char *stringData){
   if ( lastLine ) {
     lastLine = 0;
     lcd.clear();
   } else {
     lastLine = 1;
     lcd.setCursor(0,1);
   }
   lcd.print(stringData);
}

void setup() {
  lcd.begin(16,2);
  Firmata.setFirmwareVersion( FIRMATA_MAJOR_VERSION, FIRMATA_MINOR_VERSION );
  Firmata.attach( STRING_DATA, stringDataCallback);
  Firmata.begin();  
}

void loop() {
  while ( Firmata.available() ) {
    Firmata.processInput();
  }
}

lcdWeather.py

from pyfirmata import Arduino, util, STRING_DATA
import requests, time
board = Arduino('COM6')

def msg( text ):
    if text:
        board.send_sysex( STRING_DATA, util.str_to_two_byte_iter( text ) )
    else:
        board.send_sysex( STRING_DATA, util.str_to_two_byte_iter( ' ' ) )

def load():
    msg('Atualizando...')
    rio = requests.get('http://api.hgbrasil.com/weather/?format=json&cid=BRXX0201')
    rio_json = rio.json()['results']
    msg('Carregou')
    screens = [
    [ rio_json['city_name'], rio_json['date'] + ' ' + rio_json['temp'] + 'C' ],
    [ rio_json['city_name'], rio_json['description'] ],
    [ rio_json['city_name'], 'Min:'+rio_json['forecast'][0]['min']+'C Max:' + rio_json['forecast'][0]['max'] + 'C' ],
    [ rio_json['city_name'], 'Vento:'+rio_json['wind_speedy'] ],
    [ rio_json['city_name'], 'Humidade:' + rio_json['humidity'] + '%' ],
    [ rio_json['forecast'][1]['weekday'] + ' ' +  rio_json['forecast'][1]['date'], rio_json['forecast'][1]['description'] ],
    [ rio_json['forecast'][1]['weekday'] + ' ' +  rio_json['forecast'][1]['date'], 'Min:'+rio_json['forecast'][1]['min']+'C Max:' + rio_json['forecast'][1]['max'] + 'C' ],
    [ rio_json['forecast'][2]['weekday'] + ' ' +  rio_json['forecast'][2]['date'], rio_json['forecast'][2]['description'] ],
    [ rio_json['forecast'][2]['weekday'] + ' ' +  rio_json['forecast'][2]['date'], 'Min:'+rio_json['forecast'][2]['min']+'C Max:' + rio_json['forecast'][2]['max'] + 'C'  ],
    [ rio_json['forecast'][3]['weekday'] + ' ' +  rio_json['forecast'][3]['date'], rio_json['forecast'][3]['description'] ],
    [ rio_json['forecast'][3]['weekday'] + ' ' +  rio_json['forecast'][3]['date'], 'Min:'+rio_json['forecast'][3]['min']+'C Max:' + rio_json['forecast'][3]['max'] + 'C'  ],
    [ 'Atualizado em', time.asctime()[:16] ]
    ]
    return screens

screens = load()
start_time = time.time()
while (True):
    time_now = time.time()
    if (time_now - start_time) > 1800.0:
        screens = load()
        start_time = time.time()
    for screen in screens:
        msg(screen[0])
        time.sleep(0.01)
        msg(screen[1])
        time.sleep(2)

I have just started using pyfirmata, and I am trying to get a message sent from Arduino.

Arduino Code:

Firmata.begin(57600);
Firmata.sendString("Hello world");

//
How do I get that message on my pc using pyfirmata? Thanks

great code, Thank you.

I have just started using pyfirmata, and I am trying to get a message sent from Arduino.

Arduino Code:

Firmata.begin(57600);
Firmata.sendString("Hello world");

//
How do I get that message on my pc using pyfirmata? Thanks

@jesualdocc you need to implement a command handler for STRING_DATA using the add_cmd_handler method of the Board object.

Hey man when I try to send a long string the last couple letters get corrupted any fix?

Hey man when I try to send a long string the last couple letters get corrupted any fix?

How long is your string?

How to connect display using python Arduino
Can you show me any diagram of circuit
Please.....

This helped me get an RSS feed ticking across my panel, tysm <3

@ZacharyTalis awesome! Would you share some pictures if i'm not asking too much? :)

@varlen Took me a month, but: here ya go! https://diode.zone/w/qZ6XjGWYRuxen3SkFZnGX7

lcd.setCursor doesn't work inside of the stringDataCallback function but does in setup and loop. How do I fix this?

This is an amazing example. I have not tested my example out yet but this seems so simple and obvious! Thank you! Do you have any good reference to the pyfirmata project? The documentation I am seeing are simply too basic and does not cover any of the packages such as the use of STRING_DATA?

@varlen thank you!

@nildude I believe that the firmata protocol docs may help you https://github.com/firmata/protocol/blob/master/protocol.md

Thanks for the inspiring feedback :)

Hi, I'm using Arduino Uno and HD44780 16x2 LCD screen with an I2C converter. I've just copied your first code but instead pyfirmata I'm using pyfirmata2. I've added an extra line of code "print("code works")" just to check if everything is working and everything works perfectly but after running a script my display goes out and lights up but instead of my text "Hello" I still have old text which I've loaded by Arduino IDE. I would like to load or display my own text by python via Studio Visual Code without using Arduino IDE. Any idea? Thx for help!

hey, when i do it it dosent work i am using a techspace learning I2C converter 🙂

@wonton1234 i also dont have a working camera to show you...