Sparkfun: PIR Motion Sensor

Overview
The PIR Motion Sensor can be purchased from SparkFun. The datasheet describes it:

''Easy-to-use motion detector with an analog interface. Power it with 5-12VDC, and you'll be alerted of any movement.''

Arduino Tutorial

Inputs and Outputs
This unit works great from 5 to 12V (datasheet shows 12V). You can also install a jumper wire past the 5V regulator on board to make this unit work at 3.3V. Sensor uses 1.6mA@3.3V.

Sample C Code
The code shown below is sample code to demonstrate reading analog output from the ADXL335.


 * 1) include 
 * 2) include 
 * 3) include 
 * 4) include 
 * 5) include 
 * 6) include 
 * 7) include 
 * 8) include 
 * 9) include 
 * 10) include "gpio.h"

/**************************************************************** * Constants ****************************************************************/ /* {"gpio1_6", "gpio1_7", "gpio1_2", "gpio1_3", "gpio1_13", "gpio1_12", "gpio1_15", "gpio1_14"} */
 * 1) define SYSFS_GPIO_DIR "/sys/class/gpio"
 * 2) define POLL_TIMEOUT (3 * 1000) /* 3 seconds */
 * 3) define MAX_BUF 64

/**************************************************************** * Global variables ****************************************************************/ int keepgoing = 1;	// Set to 0 when ctrl-c is pressed

/**************************************************************** * signal_handler ****************************************************************/ // Callback called when SIGINT is sent to the process (Ctrl-C) void signal_handler(int sig) {	printf( "Ctrl-C pressed, cleaning up and exiting..\n" ); keepgoing = 0; }

/**************************************************************** * main ****************************************************************/ int main(int argc, char **argv) {	struct pollfd fdset[2]; int nfds = 2; int gpio_fd, timeout, rc; char *buf[MAX_BUF]; unsigned int gpio; int len;

if (argc < 2) { printf("Usage: gpio-int \n\n"); printf("Waits for a change in the GPIO pin voltage level or input on stdin\n"); exit(-1); }

// Set the signal callback for Ctrl-C signal(SIGINT, signal_handler);

gpio = atoi(argv[1]);

gpio_export(gpio); gpio_set_dir(gpio, 0); gpio_set_edge(gpio, "falling"); // Can be rising, falling or both gpio_fd = gpio_fd_open(gpio);

timeout = POLL_TIMEOUT;

while (keepgoing) { memset((void*)fdset, 0, sizeof(fdset));

fdset[0].fd = STDIN_FILENO; fdset[0].events = POLLIN; fdset[1].fd = gpio_fd; fdset[1].events = POLLPRI;

rc = poll(fdset, nfds, timeout);

if (rc < 0) { printf("\npoll failed!\n"); return -1; }		if (rc == 0) { printf("."); }		if (fdset[1].revents & POLLPRI) { lseek(fdset[1].fd, 0, SEEK_SET); // Read from the start of the file len = read(fdset[1].fd, buf, MAX_BUF); printf("\nMotion Detected, value=%c, len=%d\n",				 buf[0], len); usleep(5000000); }

if (fdset[0].revents & POLLIN) { (void)read(fdset[0].fd, buf, 1); printf("\npoll stdin read 0x%2.2X\n", (unsigned int) buf[0]); }

fflush(stdout); }

gpio_fd_close(gpio_fd); return 0; }