Created
August 14, 2017 07:32
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Shutdown the Raspbian when GPIO24 is continuously HIGH for 5 seconds
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@reboot /usr/local/bin/powerloss_watch & |
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#include <stdio.h> | |
#include <stdlib.h> | |
#include <signal.h> | |
#include <wiringPi.h> | |
#define PIN_POWERLOSS_IN (5) // BCM GPIO24 (Header Pin 18) | |
#define READ_INTERVAL (100) // msec | |
#define COUNT_TO_SHUTDOWN (50) // x {READ_INTERVAL}msec | |
void signal_handler(int signum); | |
void init() | |
{ | |
setenv("WIRINGPI_GPIOMEM", "1", 1); | |
if(-1 == wiringPiSetup()) | |
{ | |
fprintf(stderr, "wiringPiSetup() failed\n"); | |
exit(1); | |
} | |
pinMode(PIN_POWERLOSS_IN, INPUT); | |
pullUpDnControl(PIN_POWERLOSS_IN, PUD_DOWN); | |
} | |
void set_signal_handler(int signum) | |
{ | |
if(SIG_ERR == signal(signum, signal_handler)) | |
{ | |
fprintf(stderr, "set_signal_handler failed\n"); | |
exit(1); | |
} | |
} | |
void signal_handler(int signum) | |
{ | |
fprintf(stderr, "signal_handler: got signal %d\n", signum); | |
exit(1); | |
} | |
void run() | |
{ | |
int on_count = 0; | |
int prev_in = 0; | |
int current_in = 0; | |
int prev_read_value = 0; | |
while(1) | |
{ | |
int read_value = digitalRead(PIN_POWERLOSS_IN); | |
if(prev_read_value == read_value) | |
{ | |
current_in = read_value; | |
} | |
if(prev_in != current_in) | |
{ | |
fprintf(stderr, "state changed %d to %d\n", prev_in, current_in); | |
} | |
if(1 == current_in) | |
{ | |
on_count++; | |
if(on_count >= COUNT_TO_SHUTDOWN) | |
{ | |
break; | |
} | |
} | |
else | |
{ | |
on_count = 0; | |
} | |
prev_in = current_in; | |
prev_read_value = read_value; | |
delay(READ_INTERVAL); | |
} | |
} | |
int main() | |
{ | |
set_signal_handler(SIGINT); | |
set_signal_handler(SIGTERM); | |
init(); | |
run(); | |
return 0; | |
} |
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gpio_shutdown: gpio_shutdown.o | |
cc -o $@ $^ -lwiringPi | |
.c.o: | |
cc -c $< | |
clean: | |
@rm gpio_shutdown | |
@rm gpio_shutdown.o |
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#!/bin/sh | |
/usr/local/bin/gpio_shutdown | |
/sbin/shutdown -h now |
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