Question

我只有我的RPi 3B和I²C显示器，我没有任何GrovePi帽子，我想在该显示器上显示一些文本。有办法使它起作用吗？

My display。
i2cdetect -y 1显示此result，表示RPi正在检测I²C显示，它应该可以工作。但是，除了第一行的完整块之外，似乎什么都没有显示。
我已经尝试了互联网上的所有内容，有些库可以正常工作（如无错误），但是显示仍然保持不变，第一行显示完整的块。
我已经安装了python3，smbus，smbus2和i2c-tools。我已将地址更改为3e。
我最近的 *。py 文件。它确实写有“ LCD打印”，但没有其他作用。
我找不到改变LCD对比度的方法（没有电位计或其他功能）

#!/usr/bin/python3

import smbus2 as smbus
import time

# Define some device parameters
I2C_ADDR = 0x3e     # I2C device address, if any error, change this address to 0x3f
LCD_WIDTH = 16      # Maximum characters per line

# Define some device constants
LCD_CHR = 1     # Mode - Sending data
LCD_CMD = 0     # Mode - Sending command

LCD_LINE_1 = 0x80   # LCD RAM address for the 1st line
LCD_LINE_2 = 0xC0   # LCD RAM address for the 2nd line
LCD_LINE_3 = 0x94   # LCD RAM address for the 3rd line
LCD_LINE_4 = 0xD4   # LCD RAM address for the 4th line

LCD_BACKLIGHT = 0x08  # On

ENABLE = 0b00000100     # Enable bit

# Timing constants
E_PULSE = 0.0005
E_DELAY = 0.0005

# Open I2C interface
# bus = smbus.SMBus(0)  # Rev 1 Pi uses 0
bus = smbus.SMBus(1)    # Rev 2 Pi uses 1


def lcd_init():
    # Initialise display
    lcd_byte(0x33, LCD_CMD)     # 110011 Initialise
    lcd_byte(0x32, LCD_CMD)     # 110010 Initialise
    lcd_byte(0x06, LCD_CMD)     # 000110 Cursor move direction
    lcd_byte(0x0C, LCD_CMD)     # 001100 Display On,Cursor Off, Blink Off
    lcd_byte(0x28, LCD_CMD)     # 101000 Data length, number of lines, font size
    lcd_byte(0x01, LCD_CMD)     # 000001 Clear display
    time.sleep(E_DELAY)


def lcd_byte(bits, mode):
    # Send byte to data pins
    # bits = the data
    # mode = 1 for data
    #        0 for command

    bits_high = mode | (bits & 0xF0) | LCD_BACKLIGHT
    bits_low = mode | ((bits << 4) & 0xF0) | LCD_BACKLIGHT

    # High bits
    bus.write_byte(I2C_ADDR, bits_high)
    lcd_toggle_enable(bits_high)

    # Low bits
    bus.write_byte(I2C_ADDR, bits_low)
    lcd_toggle_enable(bits_low)


def lcd_toggle_enable(bits):
    # Toggle enable
    time.sleep(E_DELAY)
    bus.write_byte(I2C_ADDR, (bits | ENABLE))
    time.sleep(E_PULSE)
    bus.write_byte(I2C_ADDR, (bits & ~ENABLE))
    time.sleep(E_DELAY)


def lcd_string(message, line):
    # Send string to display
    message = message.ljust(LCD_WIDTH, " ")

    lcd_byte(line, LCD_CMD)

    for i in range(LCD_WIDTH):
        lcd_byte(ord(message[i]), LCD_CHR)


if __name__ == '__main__':
    lcd_init()

    while True:
        # Send some test
        lcd_string("Hello      ", LCD_LINE_1)
        lcd_string("      World", LCD_LINE_2)
        print('LCD printing!')
        time.sleep(3)

Grove I2C显示器无法在Raspberry Pi 3B上运行

0 个答案: