NEC红外（ir）解码协议

一、时序

一个完整的NEC解码协议，由以下几个部分组成，其中数据位为低位先行
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详细的数据格式如下，其中如果一直按住一个按钮的时候，会隔110ms左右发一次引导码
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二、代码实现

#include <string.h>
#include <stdio.h>static uint64_t time_100us = 0;
static bool ir_pin_status = false;
static EN_IR__NEC_STATE_T en_ir_state = EN_IR_NEC_STATE_IDLE;
static uint8_t ir_receive_data_count= 0;
static uint32_t ir_receive_data= 0;
static uint8_t ir_key_code= 0;static void device_ir_NEC_poll(TASK_PARAM)//定时器中断,100us触发一次，根据具体器件实现
{time_100us ++;if(time_100us >60000){time_100us = 0;}
}static void device_ir_external_irq_pressed(void)//外部中断，配置为ir接收引脚，上升沿和下降沿都触发
{ir_pin_status = platform_gpio_get_level(IR_PIN);//获取当前ir输入电平，高电平证明是上升沿触发，反之下降沿switch(en_ir_state ){case EN_IR_NEC_STATE_IDLE ://空闲状态if(ir_pin_status ==0){//下降沿触发en_ir_state = EN_IR_NEC_STATE_PREAMBLE_START_LOW;//状态改为等待9ms低电平引导码}break;case EN_IR_NEC_STATE_PREAMBLE_START_LOW://9ms低电平引导判断if((ir_pin_status ==1)&&(time_100us >=70)&&(time_100us <=110)){//满足9ms电平引导时序en_ir_state = EN_IR_NEC_STATE_PREAMBLE_START_HIGH;//状态改为等待高电平引导码}else{en_ir_state = EN_IR_NEC_STATE_IDLE;//校验失败，返回空闲状态}break;case EN_IR_NEC_STATE_PREAMBLE_START_HIGH://4.5ms高电平引导或repeatif(ir_pin_status ==0){//下降沿触发if((time_100us >=35)&&(time_100us <=60)){//4.5ms高电平引导en_ir_state = EN_IR_NEC_STATE_RECEIVE_DECODE;//状态改为接收数据ir_receive_data_count= 0;//清空接收计次ir_receive_data= 0;//清空接收数据} else if ((time_100us >=15)&&(time_100us <35)){//2.25ms高电平repeaten_ir_state = EN_IR_NEC_STATE_RECEIVE_REPEAT;//状态改为repeat}else{en_ir_state = EN_IR_NEC_STATE_IDLE;//校验失败，返回空闲状态}}else{en_ir_state = EN_IR_NEC_STATE_IDLE;//校验失败，返回空闲状态}break;case EN_IR_NEC_STATE_RECEIVE_DECODE://接收数据if(ir_pin_status == 0){//下降沿触发（即只判断高电平持续时间）if((time_100us <=8)&&(time_100us >=3)){//满足（1.12-0.56ms）存入低电平ir_receive_data >>= 1;}else if((time_100us >=12)&&(time_100us <=20)){//满足（2.25-0.56ms）存入高电平ir_receive_data = ((ir_receive_data >> 1) | 0x80000000);}else{//校验失败en_ir_state = EN_IR_NEC_STATE_IDLE;}if(++ir_receive_data_count >= 32){//接收到4个字节（两个头码和两个数据），后停止接收device_ir_NEC_decode(ir_receive_data);//数据解码en_ir_state = EN_IR_NEC_STATE_IDLE;//回到空闲状态}}break;case EN_IR_NEC_STATE_RECEIVE_REPEAT://自由选择是否继续报上一个键值break;}time_100us = 0;//每次判断完数据，需要把计数清空
}static bool device_ir_NEC_decode(uint32_t code)
{uint8_t head_code_low  = code &0x000000FF; //取出低8位数据uint8_t head_code_high = (code &0x0000FF00) >> 8; //取出低8-16位数据uint8_t key_code       = (code &0x00FF0000) >> 16; //取出低16-24位数据uint8_t key_code_minus = (code &0xFF000000) >> 24;  //取出低24-32位数据if((head_code_low ==IR_NEC_HEAD_CODE_LOW) && \   //判断是否是头码低位(head_code_high ==IR_NEC_HEAD_CODE_HIGH) && \ //判断是否是头码高位(key_code ==((~key_code_minus )&0xFF))){ //判断key_code_minus 是否是key的反码ir_key_code = key_code;//获取键值return true;}ir_key_code = 0；return false;
}bool device_ir_NEC_get_key(uint8_t *p_key)//用于给其他应用模块取得键值
{if(!ir_key_code){*p_key = ir_key_code;ir_key_code =0;//获取过键值后，清空键值return true;}return false;
}