Micro:bit Honeycomb Dot Matrix Module

Introduction

This micro:bit honeycomb dot matrix module is a sensor that is fully compatible with the micro:bit control board. This module uses an HT16K33 chip to drive an 8 * 8 dot matrix and controls dot matrix via I2C communication port of the microcontroller, which greatly saves the microcontroller resources.

In the experiment, we connect this module to the micro:bit golden finger IO shield via a crocodile clip cable, then insert Micro:bit control board to shield. Therefore, we can control dot matrix to display different patterns by setting the corresponding code on the micro:bit control board.

Specification

• Working voltage: DC 3.0-3.3V
• Control port: I2C communication port
• Environmental attributes: ROHS

Connection Diagram

Test Code

Special attention: Setting is complicated because the chip drives the dot matrix, so the program is written in Python when setting the code. from microbit import *

class ht16k33:
    ADDRESS = 0x70
    BLINK_CMD = 0x80
    CMD_BRIGHTNESS = 0xE0

    def __init__(self):
        self.buffer = bytearray([0]*16)
        i2c.write(self.ADDRESS, b'\x21')
        # 0 to 3
        self.blink_rate(0)
        # 0 to 15
        self.set_brightness(10)
        # self.clear()

    def set_brightness(self, b):
        i2c.write(self.ADDRESS, bytes([self.CMD_BRIGHTNESS | b]))

    def blink_rate(self, b):
        i2c.write(self.ADDRESS, bytes([self.BLINK_CMD | 1 | (b << 1)]))

    def Display(self, num): 
        if num == 0:
            dat = bytearray([0]*5) + bytearray([126]) + bytearray([0]) + \
                  bytearray([195]) + bytearray([0]) + bytearray([195]) + \
                  bytearray([0]) + bytearray([126]) + bytearray([0]*4)
        elif num == 1:
            dat = bytearray([0]*5) + bytearray([1]) + bytearray([0]) + \
                  bytearray([255]) + bytearray([0]) + bytearray([65]) + \
                  bytearray([0]*6)
        elif num == 2:
            dat = bytearray([0]*5) + bytearray([121]) + bytearray([0]) + \
                  bytearray([201]) + bytearray([0]) + bytearray([201]) + \
                  bytearray([0]) + bytearray([79]) + bytearray([0]*5)
        elif num == 3:
            dat = bytearray([0]*5) + bytearray([127]) + bytearray([0]) + \
                  bytearray([201]) + bytearray([0]) + bytearray([201]) + \
                  bytearray([0]) + bytearray([73]) + bytearray([0]*5)
        elif num == 4:
            dat = bytearray([0]*5) + bytearray([24]) + bytearray([0]) + \
                  bytearray([255]) + bytearray([0]) + bytearray([24]) + \
                  bytearray([0]) + bytearray([248]) + bytearray([0]*5)
        elif num == 5:
            dat = bytearray([0]*5) + bytearray([79]) + bytearray([0]) + \
                  bytearray([201]) + bytearray([0]) + bytearray([201]) + \
                  bytearray([0]) + bytearray([121]) + bytearray([0]*5)
        elif num == 6:
            dat = bytearray([0]*5) + bytearray([79]) + bytearray([0]) + \
                  bytearray([201]) + bytearray([0]) + bytearray([201]) + \
                  bytearray([0]) + bytearray([127]) + bytearray([0]*5)
        elif num == 7:
            dat = bytearray([0]*5) + bytearray([127]) + bytearray([0]) + \
                  bytearray([192]) + bytearray([0]) + bytearray([192]) + \
                  bytearray([0]) + bytearray([64]) + bytearray([0]*5)
        elif num == 8:
            dat = bytearray([0]*5) + bytearray([127]) + bytearray([0]) + \
                  bytearray([201]) + bytearray([0]) + bytearray([201]) + \
                  bytearray([0]) + bytearray([127]) + bytearray([0]*5)
        elif num == 9:
            dat = bytearray([0]*5) + bytearray([127]) + bytearray([0]) + \
                  bytearray([201]) + bytearray([0]) + bytearray([201]) + \
                  bytearray([0]) + bytearray([121]) + bytearray([0]*5)
        else:
            return
        i2c.write(self.ADDRESS, dat)
        
    def test(self):
        data = bytearray([0]) + bytearray([255]*16)
        i2c.write(self.ADDRESS, data)
        self.blink_rate(1)
        sleep(3000)
        data = bytearray([0]) + bytearray([0]*16)
        i2c.write(self.ADDRESS, data)
        self.blink_rate(0)

    def clear(self):
        self.buffer = bytearray([0]*16)
        i2c.write(self.ADDRESS, self.buffer)

# declare an instance
keyes = ht16k33()
keyes.test()
while True:
    for a in range(0, 10):
        keyes.Display(a)
        sleep(1000)

Test Result 

Wire according to connection diagram, upload the test code successfully, and after power- on, the dot matrix on the micro:bit honeycomb dot matrix module will display 0-9 10 digital patterns in a loop.

Resource

Test Code:
https://1drv.ms/u/s!ArhgRvK6-RyJhChqWXpUgiImKD_d?e=AIn3fL