用Python使用pcDuino的外部中断

pcDuino上有两个引脚可作外部中断（GPIO2和GPIO3），在网上找了下相关例子，基本上是这两个例子：

• 手把手教你使用pcDuino的外部中断 （http://cnlearn.linksprite.com/?p=1745
  
• 在pcDuino上使用Arduino风格的中断处理（http://cnlearn.linksprite.com/?p=824）

前一个是写驱动，对于我这种刚接触pcDuino的人又没有写驱动的经验的人来说，基本是看不懂，后一个是Arduio风格，使用c语言，但我使用的是Python，不想重写其它代码。

一番google后，找到了pcDuino - Interrupt Tutorial(http://digitalhacksblog.blogspot.com/2013/09/pcduinointerrupt-tutorial.html)这个教程，他也是用c语言写的， 不过不是Arduino风格，他的代码是：

#include <stdio.h> #include <signal.h>   #include <stdlib.h>    #include <inttypes.h>    #include <sys/ioctl.h>    #include <fcntl.h><p></p>// sw_interrupt must be loaded if it isn't load using   // modprobe sw_interrup<p></p>// Data structure for defining an interrupt on the pcDuino   typedef struct swIRQ {        uint8_t channel;        int mode;        int pid;    } swIRQt,*irqSWp; // Pseudo device for controlling interrupts   static const char *swirq_dev = "/dev/swirq"; #define SWIRQ_START   (0x201)   #define SWIRQ_STOP    (0x202)    #define SWIRQ_SETPID  (0x203)    #define SWIRQ_ENABLE  (0x204)    #define SWIRQ_DISABLE (0x205) #define SWIRQ_RISING  (0x00)   #define SWIRQ_FALLING (0x01)    #define SWIRQ_HIGH    (0x02)    #define SWIRQ_LOW     (0x03)    #define SWIRQ_CHANGE  (0x04) #define SWIRQ_PIN1    (0x0)   #define SWIRQ_PIN2    (0x1) int main(int _argc, char **_argv) {     int fd;      int ret;      uint8_t swIrqNum = 0;      swIRQt swIrqCfg;        // Define ISR      int irqPin1Cnt = 0;      int irqPin1Func (void) {        irqPin1Cnt++;      }   // Attach the ISR to the USR1 signal which is triggered by the OS when the interupt is signaled.     signal(SIGUSR1, (void (*) (int))irqPin1Func);   // Setup to use pin1 / gpio2 when the signal goes from low to high.     swIrqCfg.channel = SWIRQ_PIN1;      swIrqCfg.mode = SWIRQ_RISING;      swIrqCfg.pid = getpid();      swIrqNum = SWIRQ_PIN1;        // Connect a file descriptor to the pseudo device used to control interrupts      fd = open(swirq_dev, O_RDONLY);      if ( fd < 0 ) {        printf("open swirq device fail");        exit(0);      }        // Disable interrupts using pin1 / gpio2      ret = ioctl(fd, SWIRQ_STOP, &swIrqNum);      if (ret < 0) {        printf("can't set SWIRQ_STOP");        exit(0);      }        // Configure pin1 / gpio2 interrupts      ret = ioctl(fd, SWIRQ_SETPID, &swIrqCfg);      if (ret < 0) {        printf("can't set SWIRQ_SETPID");        exit(0);      }        // Enable interrupts on pin1 / gpio2      ret = ioctl(fd, SWIRQ_START, &swIrqNum);      if (ret < 0) {        printf("can't set SWIRQ_START");        exit(0);      }        // Disconnect from the pseudo device      if (fd) close(fd);       // Loop forever. Print out the counter when the ISR has been called.      int oldValue = 0;      while (2>1) {        if (oldValue != irqPin1Cnt) {          printf("irqPin1Funct: %d\n", irqPin1Cnt);          oldValue = irqPin1Cnt;        }      }    }

他的代码虽然是c写的，不过可以用Python来重写，靠加查文档边写代码，试着用Python来实现。下面是我写的代码：

import osimport sysimport signalimport structimport fcntlswirq_dev = "/dev/swirq"SWIRQ_START =   0x201 SWIRQ_STOP  =  0x202    SWIRQ_SETPID =  0x203  SWIRQ_ENABLE = 0x204  SWIRQ_DISABLE = 0x205 SWIRQ_RISING = 0x00  SWIRQ_FALLING = 0x01 SWIRQ_HIGH  =  0x02  SWIRQ_LOW  = 0x03    SWIRQ_CHANGE = 0x04 SWIRQ_PIN1 =   0x0SWIRQ_PIN2 =   0x1irqPin1Cnt = 0def irqPin1Func(a, b):    global irqPin1Cnt    irqPin1Cnt =   irqPin1Cnt + 1signal.signal(signal.SIGUSR1, irqPin1Func)pid = os.getpid()fd = open(swirq_dev)swIrqNum  = SWIRQ_PIN1fcntl.ioctl(fd, SWIRQ_STOP, struct.pack("@B",  swIrqNum))fcntl.ioctl(fd, SWIRQ_SETPID, struct.pack("@Bii", SWIRQ_PIN1, SWIRQ_RISING, pid))fcntl.ioctl(fd, SWIRQ_START, struct.pack("@B", swIrqNum))fd.close()oldValue = 0while True:    if oldValue != irqPin1Cnt:        print irqPin1Cnt        oldValue = irqPin1Cnt

我的代码基本上是用用Python改写他的代码，用到了signal、struct、fcntl这几个模块，这里要注意使用struct.pack时的格式问题，符上官方文档：

struct — Interpret strings as packed binary data（https://docs.python.org/2/library/struct.html）

字节顺序我用的是“@”，试出来的，其它的都不行。

这个程序要用root身份运行，sudo python interrupt.py，可以运行。分享一下。