我正在尝试使用 STM32F103C8T6 控制 HD44780 16X2 LCD（4 位通信）。我这样连接液晶显示器：
RS => PA0
EN => PA2
RW 接地
D7 => PB7
D6 => PB6
D5 => PB5
D4 => PB4
LCD 什么都不显示。问题可能出在哪里？有人知道这个问题吗？
这是我的代码：
#include "delay.h"
#include "stm32f10x.h" // Device header
void lcd_command(unsigned char command);
void lcd_init(void);
void lcdPosition(unsigned int row, unsigned int column);
void lcd_data(unsigned char data);
int main() {
delay_init();
RCC->APB2ENR |= 1 << 2; // Port A Enabled.
RCC->APB2ENR |= 1 << 3; // Port B Enabled.
GPIOA->CRL = 0x22222222; // A0 and A2 Output.
GPIOB->CRL = 0x22222222; // B7,B6,B5,B4 Output.
GPIOB->ODR = 0x00; // Port B clear.
delay_ms(20);
lcd_command(0x30); // Datasheet says.
delay_ms(5);
lcd_command(0x30); // Datasheet says.
delay_ms(1);
lcd_command(0x30); // Datasheet says.
delay_ms(1);
lcd_init();
lcdPosition(1, 1); // first row first column
delay_ms(1);
lcd_data('A'); // Letter A
while (1)
;
}
void lcd_command(unsigned char command) {
GPIOA->BRR |= 1 << 0; // RS reset.
GPIOA->BSRR |= 1 << 2; // E set.
GPIOB->ODR = command; // upper nibble
delay_ms(2); // delay
GPIOA->BRR |= 1 << 2; // E reset.
GPIOB->BRR = 0x000000F0; // clear data bits
delay_ms(2); // delay
command = command << 4; // lower nibble
GPIOA->BSRR |= 1 << 2; // E set.
GPIOB->ODR = command; // lower nibble
delay_ms(2); // delay
GPIOA->BRR |= 1 << 2; // E reset.
GPIOB->BRR = 0x000000FF; // clear data bits
}
void lcd_init() {
lcd_command(0x02); // Return
delay_ms(2); // delay
lcd_command(0x28);
set 4 - bit data, 2 - line, 5x7 font delay_ms(2); // delay
lcd_command(0x0C);
turn on display, cursor off.delay_ms(2); // delay
lcd_command(0x01); // Clear.
delay_ms(2); // delay
lcd_command(0x06);
move cursor right delay_ms(4); // delay
}
void lcdPosition(unsigned int row, unsigned int column) {
if (row == 1) {
column--;
lcd_command(0x80 + column); // Define row
} else if (row == 2) {
column--;
lcd_command(0xC0 + column); // Define column
}
}
void lcd_data(unsigned char data) {
GPIOA->BSRR |= 1 << 0; // RS reset.
GPIOA->BSRR |= 1 << 2; // E set.
GPIOB->ODR = data;
upper nibble first delay_ms(4); // delay
GPIOA->BRR |= 1 << 2; // E reset.
GPIOB->BRR = 0x000000F0; // clear data bits
delay_ms(4); // delay
data = data << 4; // lower nibble
GPIOA->BSRR |= 1 << 2; // E set.
GPIOB->ODR = data; // lower nibble
delay_ms(4); // delay
GPIOA->BRR |= 1 << 2; // E reset.
GPIOB->BRR = 0x000000FF; // clear data bits
}