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Circlean/ledButton_controller/ledBtn.c

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/***************************************************************************************/
/* */
/* file : ledBtn.c */
/* */
/* synopsis : */
/* the compiled code should be ran with root privileges to allow for access to */
/* the GPIO pins through direct GPIO register manipulation in C-code. */
/* After initialization, the code update the LEDs status according to the commands */
/* passed on std input (using a pipe). */
/* It also monitors the push-button and triggers a reboot sequence */
/* when it is depressed. */
/* */
/* */
/* This code is based on examples from */
/* http://elinux.org/RPi_Low-level_peripherals#C */
/* How to access GPIO registers from C-code on the Raspberry-Pi, Example program */
/* Dom and Gert, 15-January-2012, Revised: 15-Feb-2013 */
/* */
/* and from Raphael Vinot (CIRCL.lu) */
/* */
/* v 1.00 - 22/02/2015 - initial release (Marc Durvaux) */
/* v 1.10 - 27/02/2015 - added 'z' command for debugging, improved handling of */
/* concateneted command sequences */
/* */
/* */
/* */
/***************************************************************************************/
// Includes
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <errno.h>
// Constant for low-level access to GPIO
#define BCM2708_PERI_BASE 0x20000000
#define GPIO_BASE (BCM2708_PERI_BASE + 0x200000) /* GPIO controller */
#define BLOCK_SIZE (4*1024)
// global variables related to GPIO
int mem_fd ;
void *gpio_map ;
volatile unsigned *gpio ; // I/O access
// GPIO setup macros. Always use INP_GPIO(x) before using OUT_GPIO(x) or SET_GPIO_ALT(x,y)
#define INP_GPIO(g) *(gpio+((g)/10)) &= ~(7<<(((g)%10)*3))
#define OUT_GPIO(g) *(gpio+((g)/10)) |= (1<<(((g)%10)*3))
#define SET_GPIO_ALT(g,a) *(gpio+(((g)/10))) |= (((a)<=3?(a)+4:(a)==4?3:2)<<(((g)%10)*3))
#define GPIO_SET *(gpio+7) // sets bits which are 1 ignores bits which are 0
#define GPIO_CLR *(gpio+10) // clears bits which are 1 ignores bits which are 0
#define GET_GPIO(g) (*(gpio+13)&(1<<g)) // 0 if LOW, (1<<g) if HIGH
#define GPIO_PULL *(gpio+37) // Pull up/pull down
#define GPIO_PULLCLK0 *(gpio+38) // Pull up/pull down clock
// LED and push-button GPIO pin mapping (from schematic)
#define GREEN_LED 17
#define YELLOW_LED 18
#define RED_LED 22
#define PUSHBUTTON 23
// Time tic (in nsec) for loops : 10 ms
#define TIME_TIC 10000000L
// Blink half-period in tics
#define MAX_COUNT 30
// Button long pression threshold
#define LONG_PUSH 300
// forward declaration of functions
void setup_io() ;
void do_reboot() ;
/***************************************************************************************/
//
// main
// input : path and name of the FIFO must be passed as 1st argument
//
int main(int argc, char **argv) {
int fd, nbytes ;
int state, count, repeat_count ;
int Btn_state, Btn_prev_state, Btn_press_count ;
char code ;
state = 0 ; // initialize state variable
count = 0 ; // initialize loop counter
repeat_count = 0 ;
code = 0 ;
setup_io() ; // initialize GPIO pointer and GPIO pins
Btn_state = GET_GPIO( PUSHBUTTON) ; // get push-button initial state
Btn_prev_state = Btn_state ;
Btn_press_count = 0 ;
fd = open(argv[1], O_RDONLY) ;
if (fd < 0) {
perror("open") ;
exit (2) ;
}
while(1) {
Btn_state = GET_GPIO( PUSHBUTTON) ;
if (Btn_state != 0) { // button released
Btn_press_count = 0 ; // reset counter
} else { // button pressed
Btn_press_count++ ;
if (Btn_state != Btn_prev_state) {
//printf("Button pressed!\n");
if (state >= 4) { // final state, immediate reboot
close(fd) ;
do_reboot() ;
}
}
if (Btn_press_count == LONG_PUSH) { // trigger forced reboot
state = 10 ; // LED animation before reboot
repeat_count = 0 ;
}
}
Btn_prev_state = Btn_state ;
nbytes = read(fd, &code, 1) ;
if (nbytes < 0) {
perror("read") ;
exit (2) ;
}
if (nbytes > 0) {
switch (code) { // codes evaluated at every tic
case 'z' : // clear without restart (for debugging)
GPIO_CLR = 1<<GREEN_LED ;
GPIO_CLR = 1<<YELLOW_LED ;
GPIO_CLR = 1<<RED_LED ;
state = 0 ;
break ;
case 'r' : // Ready
GPIO_SET = 1<<GREEN_LED ;
state = 1 ;
break ;
case 'p' : // Processing
GPIO_CLR = 1<<GREEN_LED ;
GPIO_SET = 1<<YELLOW_LED ;
state = 2 ;
break ;
case 'e' : // Error (process aborted)
GPIO_CLR = 1<<GREEN_LED ;
GPIO_CLR = 1<<YELLOW_LED ;
GPIO_SET = 1<<RED_LED ;
state = 6 ;
break ;
case 'c' : // task successfully completed
GPIO_CLR = 1<<YELLOW_LED ;
GPIO_SET = 1<<GREEN_LED ;
state = 4 ;
count = 0 ;
break ;
case 'f' : // file processing successfully completed
GPIO_SET = 1<<GREEN_LED ;
state = 3 ;
count = 0 ;
break ;
} // end switch
}
count++ ;
if (count >= MAX_COUNT) {
count = 0 ;
switch (state) { // states evaluated after MAX_COUNT tics
case 3 : // green LED flash OFF
GPIO_CLR = 1<<GREEN_LED ;
state = 2 ;
break ;
case 4 : // green LED blinks OFF
GPIO_CLR = 1<<GREEN_LED ;
state = 5 ;
break ;
case 5 : // green LED blinks ON
GPIO_SET = 1<<GREEN_LED ;
state = 4 ;
break ;
case 10 : // start LED animation before reboot
GPIO_SET = 1<<GREEN_LED ;
GPIO_SET = 1<<YELLOW_LED ;
GPIO_SET = 1<<RED_LED ;
state = 11 ;
break ;
case 11 : // LED animation before reboot
GPIO_CLR = 1<<GREEN_LED ;
GPIO_CLR = 1<<YELLOW_LED ;
GPIO_CLR = 1<<RED_LED ;
repeat_count++ ;
if (repeat_count > 5) {
state = 12 ;
} else {
state = 10 ;
}
break ;
case 12 : // proceed with reboot
close(fd) ;
do_reboot() ;
break ;
} // end switch
} // end if
// loop delay
nanosleep((struct timespec[]){{0, TIME_TIC}}, NULL) ;
}
return 0 ; // we should never come here!
} // main
/***************************************************************************************/
//
// Set up a memory region to access GPIO
//
void setup_io() {
/* open /dev/mem */
if ((mem_fd = open("/dev/mem", O_RDWR|O_SYNC) ) < 0) {
printf("can't open /dev/mem \n");
exit(-1);
}
/* mmap GPIO */
gpio_map = mmap(
NULL, //Any adddress in our space will do
BLOCK_SIZE, //Map length
PROT_READ|PROT_WRITE,// Enable reading & writting to mapped memory
MAP_SHARED, //Shared with other processes
mem_fd, //File to map
GPIO_BASE //Offset to GPIO peripheral
);
close(mem_fd); //No need to keep mem_fd open after mmap
if (gpio_map == MAP_FAILED) {
printf("mmap error %d\n", (int)gpio_map);//errno also set!
exit(-1);
}
// Always use volatile pointer!
gpio = (volatile unsigned *)gpio_map ;
// initializes the LED and push-button pins
INP_GPIO( GREEN_LED) ; // must use INP_GPIO before we can use OUT_GPIO
OUT_GPIO( GREEN_LED) ;
INP_GPIO( YELLOW_LED) ;
OUT_GPIO( YELLOW_LED) ;
INP_GPIO( RED_LED) ;
OUT_GPIO( RED_LED) ;
INP_GPIO( PUSHBUTTON) ;
// initializes LEDs to OFF state
GPIO_CLR = 1<<GREEN_LED ;
GPIO_CLR = 1<<YELLOW_LED ;
GPIO_CLR = 1<<RED_LED ;
} // setup_io
/***************************************************************************************/
//
// Call system reboot
//
void do_reboot() {
static char *execArgv[5] ; /* define arguments for shutdown exec */
execArgv[0] = "shutdown" ;
execArgv[1] = "-r" ;
execArgv[2] = "now" ;
execArgv[3] = NULL ;
//printf("going to reboot!\n") ;
execv("/sbin/shutdown", execArgv) ;
} // do_reboot
/*** END OF FILE ***********************************************************************/
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