原理图
LED 原理图如下图所示，连接GPIO19，GPIO21，GPIO22。
按键 BUTTON 原理图如下图所示，连接 BTN1 和 BTN2 。
物理连接如下图所示。
开发板的按键引脚 BTN1 和 BTN2 分别连接到 GPIO30 和 GPIO31 。
源码
开发板的按键引脚连接到 GPIO30 和 GPIO31 。
主程序如下：
#include <stdio.h>
#include <stdlib.h>
#include "platform.h"
#include <string.h>
#include "plic/plic_driver.h"
#include "encoding.h"
#include <unistd.h>
#include "stdatomic.h"
// Structures for registering different interrupt handlers
// for different parts of the application.
typedef void (*function_ptr_t) (void);
void no_interrupt_handler (void) {};
function_ptr_t g_ext_interrupt_handlers[PLIC_NUM_INTERRUPTS];
// Instance data for the PLIC.
plic_instance_t g_plic;
//处理外部中断
void handle_m_ext_interrupt(){
plic_source int_num = PLIC_claim_interrupt(&g_plic);
if ((int_num >=1 ) && (int_num < PLIC_NUM_INTERRUPTS)) {
g_ext_interrupt_handlers[int_num]();
}
else {
exit(1 + (uintptr_t) int_num);
}
PLIC_complete_interrupt(&g_plic, int_num);
}
void button_1_handler(void) {
printf("open led");
// Green LED On
GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << RED_LED_GPIO_OFFSET);
GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << GREEN_LED_GPIO_OFFSET);
GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << BLUE_LED_GPIO_OFFSET);
// Clear the GPIO Pending interrupt by writing 1.
GPIO_REG(GPIO_RISE_IP) = (0x1 << BUTTON_1_GPIO_OFFSET);
};
void button_2_handler(void) {
printf("close led");
GPIO_REG(GPIO_OUTPUT_VAL) &= ~(1 << RED_LED_GPIO_OFFSET);
GPIO_REG(GPIO_OUTPUT_VAL) &= ~(1 << GREEN_LED_GPIO_OFFSET);
GPIO_REG(GPIO_OUTPUT_VAL) &= ~(1 << BLUE_LED_GPIO_OFFSET);
GPIO_REG(GPIO_RISE_IP) = (0x1 << BUTTON_2_GPIO_OFFSET);
};
void register_plic_irqs (){
/**************************************************************************
* Set up the PLIC
*
*************************************************************************/
PLIC_init(&g_plic,
PLIC_CTRL_ADDR,
PLIC_NUM_INTERRUPTS,
PLIC_NUM_PRIORITIES);
for (int ii = 0; ii < PLIC_NUM_INTERRUPTS; ii ++){
g_ext_interrupt_handlers[ii] = no_interrupt_handler;
}
g_ext_interrupt_handlers[PLIC_INT_DEVICE_BUTTON_1] = button_1_handler;
g_ext_interrupt_handlers[PLIC_INT_DEVICE_BUTTON_2] = button_2_handler;
// Have to enable the interrupt both at the GPIO level,
// and at the PLIC level.
PLIC_enable_interrupt (&g_plic, PLIC_INT_DEVICE_BUTTON_1);
PLIC_enable_interrupt (&g_plic, PLIC_INT_DEVICE_BUTTON_2);
// Priority must be set > 0 to trigger the interrupt.
PLIC_set_priority(&g_plic, PLIC_INT_DEVICE_BUTTON_1, 1);
PLIC_set_priority(&g_plic, PLIC_INT_DEVICE_BUTTON_2, 1);
}
int main(int argc, char **argv)
{
//关闭LED GPIO的输入使能
GPIO_REG(GPIO_INPUT_EN) &= ~((0x1<< RED_LED_GPIO_OFFSET) | (0x1<< GREEN_LED_GPIO_OFFSET) | (0x1 << BLUE_LED_GPIO_OFFSET)) ;
//打开LED GPIO的输出使能：三个颜色的LED灯
GPIO_REG(GPIO_OUTPUT_EN) |= ((0x1<< RED_LED_GPIO_OFFSET)| (0x1<< GREEN_LED_GPIO_OFFSET) | (0x1 << BLUE_LED_GPIO_OFFSET)) ;
//设置LED GPIO的输出值
GPIO_REG(GPIO_OUTPUT_VAL) &= ~ (0x1 << RED_LED_GPIO_OFFSET) ;
GPIO_REG(GPIO_OUTPUT_VAL) &= ~ (0x1 << GREEN_LED_GPIO_OFFSET) ;
GPIO_REG(GPIO_OUTPUT_VAL) &= ~ (0x1 << BLUE_LED_GPIO_OFFSET) ;
//关闭按键GPIO的输出使能
GPIO_REG(GPIO_OUTPUT_EN) &= ~((0x1<< BUTTON_1_GPIO_OFFSET) | (0x1<< BUTTON_2_GPIO_OFFSET)) ;
//关闭按键GPIO的输入上拉
GPIO_REG(GPIO_PULLUP_EN) &= ~((0x1<< BUTTON_1_GPIO_OFFSET) | (0x1<< BUTTON_2_GPIO_OFFSET)) ;
//打开GPIO的输入使能
GPIO_REG(GPIO_INPUT_EN) |= ((0x1<< BUTTON_1_GPIO_OFFSET) | (0x1<< BUTTON_2_GPIO_OFFSET)) ;
//上升沿触发的中断来源
GPIO_REG(GPIO_RISE_IE) |= ((0x1<< BUTTON_1_GPIO_OFFSET) | (0x1<< BUTTON_2_GPIO_OFFSET)) ;
printf("set gpio finish");
//关闭外部中断局部使能
clear_csr(mie, MIP_MEIP);
//计时器初始化
register_plic_irqs();
// 打开外部中断局部使能
set_csr(mie, MIP_MEIP);
//打开中断的全局使能
set_csr(mstatus, MSTATUS_MIE);
printf("set interrupt gpio finish");
return 0;
}
实验结果
按键 BTN1 会将 LED 灯关闭，按键 BTN2 会将 LED 灯打开。