001 - MakeCode MicroBit: Brickcell LCD I2C

Brickcell Development Kit comes with an LCD module which is a 16x2 LCD module with an I2C interface.

It has an alphanumeric dot matrix display screen, an HD44780 display controller developed by Hitachi, and a PCF8574T I2C to GPIO expansion IC which converts parallel IO to I2C. The LCD module can be access through 0x20 I2C address.

Working Details

• The I2C interface can only work with 4-bit mode (no 8-bit mode support).
• Register Select (RS pin):
  • Data register - contains what is displayed on the LCD
  • Instruction register - contains instructions for the display controller.
• Read/Write (R/W pin):
  • Reading mode
  • Writing mode
• Enable pin
• Data bus (8 bits, bi-directional) pin

Hardware Instruction

Let's explore how to connect the LCD I2C to a micro:bit microcontroller and utilize MakeCode for programming.

1. Connect the LCD GND pin to microbit GND pin.
2. Connect the LCD VCC pin to microbit VCC pin.
3. Connect the LCD SDA pin to microbit pin 20.
4. Connect the LCD SCL pin to microbit pin 19.

Software Instruction

Now, let's start programming the micro:bit to utilize the NTC temperature sensor.

1. Login to https://makecode.microbit.org/ using your Microsoft account.
2. Create a new project by clicking the “New Project” button. You may name it anything you want — for example, lcd-i2c-test.
3. Click the “Extensions” block just under the “Math” block.
4. Type https://github.com/gbantique/brickcell-lcd-i2c/ in the search bar.
5. Select the “brickcell-lcd-i2c” from the search results. The “lcd i2c” block should appear under the “Brickcell” block.
6. Copy the code provided below.

let loopCount = 0
Brickcell.init(0)
Brickcell.ShowString("Brickcell", 0, 0)
basic.forever(function () {
    loopCount += 1
    Brickcell.ShowNumber(loopCount, 0, 1)
    basic.pause(1000)
})

Or you can make a copy of my created project in your MakeCode workspace:

https://makecode.microbit.org/S97995-99534-94247-46039/

Expected Result

If you carefully follow the provided instructions above, you should be able to view the following on the LCD:

• First line: the word Brickcell
• Second line: a counter value that increases every 1000 milliseconds.

References And Credits

1. https://docs.arduino.cc/learn/electronics/lcd-displays/
2. https://www.playembedded.org/blog/hd44780-lcdii-and-chibioshal/
3. http://www.matidavid.com/pic/LCD%20interfacing/introduction.htm/