LINUX外接TM1650键盘，由于TM1650的接口不是标准的I2C接口，只能通过操作GPIO方式模拟I2C通信，实现对TM1650的驱动；
问题1:通过linux的文件读写GPIO方式，是否支持微秒级别拉高拉低控制，通过示波器验证没有问题，完全支持微秒级别的gpio控制；
问题2:中断引脚如何控制；
当前解决方式是轮训查询中断引脚value值来判断是否有中断；另一种方式就是使用poll监听多路复用的方式监听是否有中断产生；
代码语言：javascript复制对于使用中断可以使用poll多路复用IO监测中断是否触发，poll事件有POLLIN、POLLOUT、POLLERR、POLLPRI 等，其中 POLLIN 和 POLLOUT 表示普通优先级数据可读、可写。中断就是一种高优先级事件，需要使用 POLLPRI ，当中断触发时表示有高优先级数据可被读取。
此外还可以使用信号方式监测GPIO是否触发中断。TM1650的驱动代码参考链接实现，基于参考链接来操作GPIO，注意这个链接的几个方法没有close 文件句柄，需要注意修改；
key_pad.h
代码语言：javascript复制//key_pad.h
#ifndef KEY_PAD_
#define KEY_PAD_
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
/*************************************宏定义********************/
/*
J8707 键盘 1 SCK 144
2 SDA 145
3 INT 输入中断 194
4 Light 背光控制，IO，无驱动能力 196
*/
#define TM1650_SCK_GPIO 144
#define TM1650_SDA_GPIO 145
#define TM1650_IRQ_GPIO 194
/***********************键盘丝印值定义*****************************/
typedef enum KEY_VALUE_{
INPUT_KEY_INVALID=-1,
INPUT_KEY_0 = 0,
INPUT_KEY_1,
INPUT_KEY_2,
INPUT_KEY_3,
INPUT_KEY_4,
INPUT_KEY_5,
INPUT_KEY_6,
INPUT_KEY_7,
INPUT_KEY_8,
INPUT_KEY_9,
INPUT_KEY_STAR = 20,
INPUT_KEY_PROUND = 21,
INPUT_KEY_PAGE_UP = 22,
INPUT_KEY_PAGE_DOWN = 23,
INPUT_KEY_BACK = 24,
INPUT_KEY_OK = 25,
}KEY_VALUE;
/*************************************函数定义********************/
extern void TM1650_init(void);
extern uint8_t TM1650_Irq_Set(void);
extern void i2c_read_data(uint8_t *key_value);
//将按键值转换为键盘丝印值
extern int get_input_key_value(uint8_t key_value);
#endif//key_pad.c
代码语言：javascript复制//key_pad.c
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/select.h>
#include <unistd.h>
#include <fcntl.h>
#include "key_pad.h"
#include "gpio.h"
/*************************************函数定义********************/
static inline int gpio_input_bit_get(int gpio, uint8_t switch_in_mode);
static inline void gpio_bit_set_mode(int gpio, uint8_t in_mode);
static void TM1650_IIC_start(void);
static void TM1650_IIC_write_byte(uint8_t dat);
static uint8_t TM1650_IIC_wait_ack(void);
static void TM1650_IIC_stop(void);
static uint8_t TM1650_IIC_read_byte(void);
#define TRUE 1
#define FALSE 0
//========【配置IIC总线的信号读写和时序】=======
//主机拉高SCL
#define TM1650_IIC_SCL_HIGH gpio_bit_set(TM1650_SCK_GPIO)
//主机拉低SCL
#define TM1650_IIC_SCL_LOW gpio_bit_reset(TM1650_SCK_GPIO)
//输入
#define TM1650_IIC_SDA_SET_IN gpio_bit_set_mode(TM1650_SDA_GPIO, TRUE)
#define TM1650_IIC_SDA_SET_OUT gpio_bit_set_mode(TM1650_SDA_GPIO, FALSE)
//主机拉高SDA
#define TM1650_IIC_SDA_HIGH gpio_bit_set(TM1650_SDA_GPIO)
//主机拉低SDA
#define TM1650_IIC_SDA_LOW gpio_bit_reset(TM1650_SDA_GPIO)
//参数b为0时主机拉低SDA，非0则拉高SDA
#define TM1650_IIC_SDA_WR(b) do{
if(b) gpio_bit_set(TM1650_SDA_GPIO);
else gpio_bit_reset(TM1650_SDA_GPIO);
}while(0)
//主机读取SDA线电平状态，返回值为0为低电平，非0则为高电平
#define TM1650_IIC_SDA_RD() gpio_input_bit_get(TM1650_SDA_GPIO, FALSE)
//软件延时2us
#define TM1650_IIC_DELAY_2US do{for(int ii_=0;ii_<22;ii_ );}while(0)
//软件延时4us
#define TM1650_IIC_DELAY_4US do{sleep_inner(0, 4);}while(0)
#define TM1650_IIC_DELAY_5US do{sleep_inner(0, 5);}while(0)
/*************************************函数实现********************/
void sleep_inner (long sec, long usec) {
struct timeval timeout = {sec, usec};
int ret = 0;
if ((0 == timeout.tv_sec) || (timeout.tv_usec < 20))
{
//printf("local sleep_inner error! input sleep_inner time must greater than 20ms !n");
//timeout.tv_usec = 20;
}
ret = select(0, NULL, NULL, NULL, &timeout);
if ((-1 == ret) || (ret))
{
printf("local sleep_inner error!n");
}
}
void i2c_read_data(uint8_t *key_value){
TM1650_IIC_start();
TM1650_IIC_write_byte(0x49); //起始地址 0x49
TM1650_IIC_wait_ack();
*key_value = TM1650_IIC_read_byte();
TM1650_IIC_stop();
printf("%s exit test rn",__FUNCTION__);
}
void i2c_write_data(uint8_t address, uint8_t data){
TM1650_IIC_start();
TM1650_IIC_write_byte(address); TM1650_IIC_wait_ack(); //显存起始地址为0x68
TM1650_IIC_write_byte(data); TM1650_IIC_wait_ack(); //发送段码
TM1650_IIC_stop();
}
static inline void key_gpio_init(int gpio){
gpio_unexport(gpio);
#if 1
char cmd[255] = "";
sprintf(cmd, "echo %d > /sys/class/gpio/export", gpio);
system(cmd);
#else
gpio_export(gpio);
#endif
}
static int tm1650_init_inner()
{
TM1650_IIC_start();
TM1650_IIC_write_byte(0x48);
TM1650_IIC_wait_ack();
TM1650_IIC_write_byte(0x08|0x00|0x01); //0x08:7段模式；0x00：正常工作模式；0x01：开屏（开启键扫描）
TM1650_IIC_wait_ack();
TM1650_IIC_stop();
return 0;
}
//TM1650初始化
void TM1650_init(void)
{
key_gpio_init(TM1650_SCK_GPIO);
key_gpio_init(TM1650_SDA_GPIO);
key_gpio_init(TM1650_IRQ_GPIO);
gpio_direction_input(TM1650_IRQ_GPIO);
//gpio_edge_falling(TM1650_IRQ_GPIO);
gpio_direction_output(TM1650_SCK_GPIO);
gpio_direction_output(TM1650_SDA_GPIO);
sleep_inner(0,5000);//
tm1650_init_inner();
sleep_inner(0,5000);//
printf("TM1650_init endrn");
}
uint8_t TM1650_Irq_Set(void){
int ret = gpio_get_value(TM1650_IRQ_GPIO);
if (ret == 0){
return TRUE;
}
return FALSE;
}
static inline void gpio_bit_set_inner(int gpio, uint8_t high){
#if 0
char cmd[255] = "";
sprintf(cmd, "echo out > /sys/class/gpio/gpio%d/direction", gpio);
//printf("cmd1:%srn", cmd);
system(cmd);
sprintf(cmd, "echo %d > /sys/class/gpio/gpio%d/value", high?1:0, gpio);
//printf("cmd2:%srn", cmd);
system(cmd);
#else
gpio_set_value(gpio, high);
#endif
}
void gpio_bit_set(int gpio){
gpio_bit_set_inner(gpio, 1);
}
void gpio_bit_reset(int gpio){
gpio_bit_set_inner(gpio, 0);
}
static inline void gpio_bit_set_mode(int gpio, uint8_t in_mode){
#if 0
char cmd[255] = "";
if (in_mode){
sprintf(cmd, "echo in > /sys/class/gpio/gpio%d/direction", gpio);
system(cmd);
}else{
sprintf(cmd, "echo out > /sys/class/gpio/gpio%d/direction", gpio);
system(cmd);
}
//printf("gpio_bit_set_mode, cmd:%srn", cmd);
#else
if (in_mode){
gpio_direction_input(gpio);
}else{
gpio_direction_output(gpio);
}
#endif
}
static inline int gpio_input_bit_get(int gpio, uint8_t switch_in_mode){
#if 1
if (switch_in_mode){
gpio_bit_set_mode(gpio, 1);
}
return gpio_get_value(gpio);
#else
FILE *fp = NULL;
int rc = 0; // 用于接收命令返回值
int value =0;
char cmd[255] = "";
char result_buf[255] = "";
sprintf(cmd, "echo in > /sys/class/gpio/gpio%d/direction", gpio);
if (switch_in_mode){
//printf("gpio_input_bit_get:%srn", cmd);
system(cmd);
}
sprintf(cmd, "cat /sys/class/gpio/gpio%d/value", gpio);
fp = popen(cmd, "r");
if(NULL == fp)
{
printf("popen执行失败！");
return (0);
}
while(fgets(result_buf, sizeof(result_buf), fp) != NULL)
{
value = atoi(result_buf);
}
rc = pclose(fp);
if(-1 == rc)
{
printf("关闭文件指针失败rn");
return (0);
}
return value;
#endif
}
//产生IIC总线起始信号
static void TM1650_IIC_start(void)
{
TM1650_IIC_SDA_SET_OUT;
TM1650_IIC_SCL_HIGH; //SCL=1
TM1650_IIC_SDA_HIGH; //SDA=1
TM1650_IIC_DELAY_5US;
TM1650_IIC_SDA_LOW; //SDA=0
TM1650_IIC_DELAY_5US;
TM1650_IIC_SCL_LOW; //SCL=0
}
//通过IIC总线发送一个字节
static void TM1650_IIC_write_byte(uint8_t dat)
{
uint8_t i;
TM1650_IIC_SDA_SET_OUT;
TM1650_IIC_SCL_LOW;
for(i=0;i<8;i )
{
TM1650_IIC_SDA_WR(dat&0x80);
dat<<=1;
TM1650_IIC_DELAY_5US;
TM1650_IIC_SCL_HIGH;
TM1650_IIC_DELAY_5US;
TM1650_IIC_SCL_LOW;
TM1650_IIC_DELAY_5US;
}
}
//通过IIC总线读一个字节
static uint8_t TM1650_IIC_read_byte(void)
{
uint8_t i;
uint8_t read_key = 0;
//printf("%s enter test rn",__FUNCTION__);
TM1650_IIC_SDA_SET_IN;
for(i=0;i<8;i )
{
TM1650_IIC_SCL_LOW;
TM1650_IIC_DELAY_5US;
TM1650_IIC_SCL_HIGH;
read_key <<=1;
int value = gpio_input_bit_get(TM1650_SDA_GPIO, FALSE);
if (value == 1){
read_key ;
}
TM1650_IIC_DELAY_5US;
}
TM1650_IIC_SDA_SET_OUT;
//printf("%s exit test rn",__FUNCTION__);
return read_key;
}
//通过IIC总线接收从机响应的ACK信号
static uint8_t TM1650_IIC_wait_ack(void)
{
uint8_t ack_signal = 0;
int times_wait = 0;
TM1650_IIC_SDA_SET_OUT;
TM1650_IIC_SDA_HIGH; //SDA=1
TM1650_IIC_DELAY_5US;
TM1650_IIC_SCL_HIGH;
TM1650_IIC_DELAY_5US;
TM1650_IIC_SDA_SET_IN;
do{
if(TM1650_IIC_SDA_RD()) {
ack_signal = 1; //如果读取到的是NACK信号
break;
}
}while(times_wait < 300);
TM1650_IIC_SCL_LOW;
TM1650_IIC_DELAY_2US;
return ack_signal;
}
//产生IIC总线结束信号
static void TM1650_IIC_stop(void)
{
TM1650_IIC_SDA_SET_OUT;
TM1650_IIC_SCL_LOW; //SCL=0
TM1650_IIC_SDA_LOW; //SDA=0
TM1650_IIC_DELAY_5US;
TM1650_IIC_SCL_HIGH; //SCL=1
TM1650_IIC_DELAY_5US;
TM1650_IIC_SDA_HIGH; //SDA=1
}
//将按键值转换为键盘丝印值
int get_input_key_value(uint8_t key_value){
switch(key_value){
case 0x64:
return INPUT_KEY_OK;
case 0x65:
return INPUT_KEY_PROUND;
case 0x66:
return INPUT_KEY_0;
case 0x67:
return INPUT_KEY_STAR;
case 0x4C:
return INPUT_KEY_BACK;
case 0x4D:
return INPUT_KEY_9;
case 0x4E:
return INPUT_KEY_8;
case 0x4F:
return INPUT_KEY_7;
case 0x44:
return INPUT_KEY_INVALID;
case 0x45:
return INPUT_KEY_INVALID;
case 0x46:
return INPUT_KEY_INVALID;
case 0x47:
return INPUT_KEY_INVALID;
default:
return INPUT_KEY_INVALID;
}
return INPUT_KEY_INVALID;
}有中断信号时，读键盘的按键值，主函数实现：
代码语言：javascript复制 TM1650_init();
sleep_ms(20);
while(1){
if (TM1650_Irq_Set())
{
i2c_read_data(&input_key);
printf("input_key:x:%drn", input_key, get_input_key_value(input_key));
}
sleep_ms(10);
}几个报错处理：
1、开始通过文件方式操作export文件，发现总是失败；
[failed]gpio_export path:/sys/class/gpio/gpio145
open error: Permission denied
[failed]gpio_export path:/sys/class/gpio/gpio194
open error: Permission denied
[failed]gpio_cfg_attr path:/sys/class/gpio/gpio145/value
open error: No such file or directory
解决：使用如下命令执行后，再操作gpio就没有问题：
system("echo 199 > /sys/class/gpio/export");
2、sh: write error: Device or resource busy
未做处理，应该是权限控制问题；
3、write error: Operation not permited.
问题原因：direction是in时，写value失败
root@fsu:/home/fsu# echo 199 > /sys/class/gpio/export
root@fsu:/home/fsu# echo in > /sys/class/gpio/gpio199/direction
root@fsu:/home/fsu# echo 1 > /sys/class/gpio/gpio199/value
ash: write error: Operation not permitted
root@fsu:/home/fsu#
4、too many open file
文件打开没有close，网上找的gpio文件操作的代码（参考链接）有问题，操作完文件没有close；
