[RPi4] I2C LCD & Python

0. Ref

https://learn.adafruit.com/adafruit-16x2-character-lcd-plus-keypad-for-raspberry-pi/python-usage

Adafruit 16x2 Character LCD + Keypad for Raspberry Pi

1. 연결

RPi4	I2C LCD 20x4
5V (2, 4)	VCC
GND (6, 9, 14, ...)	GND
SDA (3)	SDA
SCL (5)	SCL

2. 샘플 코드

import board
import busio
import adafruit_character_lcd.character_lcd_i2c as character_lcd
lcd_columns = 20
lcd_rows = 4
i2c = busio.I2C(board.SCL, board.SDA)
lcd = character_lcd.Character_LCD_I2C(i2c, lcd_columns, lcd_rows)
lcd.clear()
lcd.message = "Hello\nCircuitPython"

실행

python3 lcd.py

Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/adafruit_bus_device/i2c_device.py", line 154, in __probe_for_device
    self.i2c.writeto(self.device_address, b"")
  File "/usr/local/lib/python3.7/dist-packages/busio.py", line 166, in writeto
    return self._i2c.writeto(address, buffer, stop=stop)
  File "/usr/local/lib/python3.7/dist-packages/adafruit_blinka/microcontroller/generic_linux/i2c.py", line 49, in writeto
    self._i2c_bus.write_bytes(address, buffer[start:end])
  File "/usr/local/lib/python3.7/dist-packages/Adafruit_PureIO/smbus.py", line 314, in write_bytes
    self._device.write(buf)
OSError: [Errno 121] Remote I/O error

3. 연결확인

pi@raspberrypi:~ $ i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- 27 -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

4. 엘레파츠 블로그 확인

https://blog.naver.com/PostView.naver?blogId=elepartsblog&logNo=221583231746&parentCategoryNo=&categoryNo=34&viewDate=&isShowPopularPosts=false&from=postView 

라즈베리파이에서 파이썬으로 1602 I2C 캐릭터 LCD 사용하기

5. 샘플 코드 다운로드, 실행

git clone https://github.com/eleparts/RPi_I2C_LCD_driver
cd RPi_I2C_LCD_driver
python3 example.py