MQTT-Enabled Scrolling Text with ATOM Matrix and MicroPython

For Windows:

1. Install Python, Esptool, and Ampy

If you have no Python 3 installation on your computer, please download the installer from https://www.python.org/downloads/ and execute it. Then install Esptool and Ampy with

> pip3 install esptool

> pip3 install adafruit-ampy

on the command line.

 2. Download and Install Firmware

Download https://micropython.org/resources/firmware/esp32-20220618-v1.19.1.bin. Connect your ATOM Matrix to your computer via USB. If you are connecting it the first time wait a little until Windows installs the driver. Open the Windows Device Manager and look into "COM & LPT" to find the correct COM port, e.g., COM6. Then install the firmware with

> esptool.py --chip esp32 --port COM6 erase_flash

> esptool.py --chip esp32 --port COM6 write_flash -z 0x1000 esp32-20220618-v1.19.1.bin

Reset your device after the installation is finished.

 3. Download and Install Libraries

Create a folder named lib on your computer. Download the files cooperative_multitasking.mpy, font5.mpy, mqtt.mpy, mqtt_client.mpy and neopixel_scroller.mpy from https://bitbucket.org/amotzek/micro-python/downloads/ into that lib folder. In the command line navigate to the folder above lib and then execute

> ampy.exe --port COM6 --delay 3 put lib

to upload the folder to your ATOM Matrix.

 4. Edit and Upload main.py

From the Code section of this project copy the file main.py to your computer and fill in your WLAN credentials in line 21, a username in line 19, and a MQTT topic name in line 49. Execute

> ampy.exe --port COM6 --delay 3 put main.py

to upload the file to your ATOM Matrix.

 5. Test

In your browser go to http://www.hivemq.com/demos/websocket-client/. Click the Connect button. Enter the topic name from line 49 into the Topic field. Enter

{ "message": "HELLO!" }

into the Message field. Click the Publish button. Your ATOM Matrix should display HELLO! now.

Only capital letters A to Z, digits and some other characters can be displayed. For a complete list see the source code of Font5 at https://bitbucket.org/amotzek/micro-python/src/master/src/main/modules/font5.py.

Code

import uos
from cooperative_multitasking import Tasks
from network import WLAN, AP_IF
from mqtt_client import MQTTClient
from machine import Pin
from neopixel import NeoPixel
from font5 import Font5
from neopixel_scroller import NeopixelScroller

tasks = Tasks()

ap = WLAN(AP_IF)
ap.active(False)
ap = None

client = MQTTClient(tasks,
                    hostname = 'broker.mqttdashboard.com',
                    client_id = '',
                    user_name = '...',
                    password = '')
client.activate_wlan([('...', '...')])
client.start()

gpio27 = Pin(27, Pin.OUT)
neopixels = NeoPixel(gpio27, 25)
font = Font5()
colors = [(20, 0, 0), (20, 20, 0), (0, 20, 0), (0, 0, 20)]
scroller = None

def randint(low, high):
    s = 0
    bs = uos.urandom(4)
    for b in bs:
        s = (s << 8) | b
    return low + (s % (high - low + 1))

def random_color():
    return colors[randint(0, len(colors) - 1)]

def receive_message(topic, payload_object):
    global scroller
    try:
        message = payload_object['message']
        color = random_color()
        scroller = NeopixelScroller(neopixels, message, font, foreground_color=color)
    except:
        pass

client.subscribe('...', receive_message)

def has_message():
    return scroller is not None

def await_message():
    tasks.when_then(has_message, scroll_message)

def is_connected():
    return client.is_connected()

def scroll_message():
    scroller.scroll()
    neopixels.write()
    if is_connected():
        tasks.after(300, scroll_message)
    else:
        tasks.now(clear_display)

def clear_display():
    global scroller
    scroller = None
    for pixel_index in range(25):
        neopixels[pixel_index] = (0, 0, 0)
    neopixels.write()
    tasks.now(await_message)

tasks.now(await_message)

while tasks.available():
    tasks.run()