/*********************************************************************************
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* Copyright: (C) 2021 LingYun IoT System Studio
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* All rights reserved.
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*
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* Filename: pwm.c
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* Description: This file is used to control PWM buzzer/Led
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*
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* Pin connection:
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* PWM Module Raspberry Pi Board
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* VCC <-----> 5V
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* buzzer <-----> #Pin32(BCM GPIO12)
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* Led <-----> #Pin33(BCM GPIO13)
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* GND <-----> GND
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*
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* /boot/config.txt:
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*
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* dtoverlay=pwm,pin=12,func=4 (Buzzer)
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* dtoverlay=pwm,pin=13,func=4 (Led)
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*
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********************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <dirent.h>
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#include <string.h>
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#include <time.h>
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#include <errno.h>
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#include <signal.h>
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#include <getopt.h>
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#include <libgen.h>
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#include "logger.h"
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#include "util_proc.h"
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#include "pwm.h"
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/* check PWM $channel export or not */
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int check_pwm(int channel)
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{
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char path[256];
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/* check /sys/class/pwm/pwmchip0/pwmN exist or not */
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snprintf(path, sizeof(path), "%s/pwm%d", PWMCHIP_PATH, channel);
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return access(path, F_OK) ? 0 : 1;
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}
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/* export($export=1)/unexport($export=0) PWM $channel */
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int export_pwm(int channel, int export)
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{
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int fd;
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char buf[32];
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char path[256];
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if( export && check_pwm(channel) )
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return 0; /* export already when export */
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else if( !export && !check_pwm(channel) )
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return 0; /* unexport already when unexport */
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/* export PWM channel by echo N > /sys/class/pwm/pwmchip0/export */
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snprintf(path, sizeof(path), "%s/%s", PWMCHIP_PATH, export?"export":"unexport");
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if( (fd=open(path, O_WRONLY)) < 0 )
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{
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log_error("open '%s' failed: %s\n", path, strerror(errno));
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return -3;
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}
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snprintf(buf, sizeof(buf), "%d", channel);
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write(fd, buf, strlen(buf));
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msleep(100);
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if( export && check_pwm(channel) )
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return 0; /* export already when export */
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else if( !export && !check_pwm(channel) )
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return 0; /* unexport already when unexport */
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return -4;
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}
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/* configure PWM $channel */
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int config_pwm(int channel, int freq, int duty)
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{
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int fd;
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char buf[32];
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char path[256];
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int period;
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int duty_cycle;
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if( !check_pwm(channel) )
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return -2;
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/* open PWM period file and write period in ns */
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snprintf(path, sizeof(path), "%s/pwm%d/period", PWMCHIP_PATH, channel);
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if( (fd=open(path, O_WRONLY)) < 0 )
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{
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log_error("open '%s' failed: %s\n", path, strerror(errno));
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return -3;
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}
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period = 1000000000/freq;
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snprintf(buf, sizeof(buf), "%d", period);
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write(fd, buf, strlen(buf));
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/* open PWM duty_cycle file and write duty */
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snprintf(path, sizeof(path), "%s/pwm%d/duty_cycle", PWMCHIP_PATH, channel);
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if( (fd=open(path, O_WRONLY)) < 0 )
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{
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log_error("open '%s' failed: %s\n", path, strerror(errno));
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return -3;
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}
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duty_cycle = (period*duty) / 100;
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snprintf(buf, sizeof(buf), "%d", duty_cycle);
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write(fd, buf, strlen(buf));
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return 0;
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}
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int init_pwm(int channel, int freq, int duty)
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{
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int rv;
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char buf[32];
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char path[256];
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if( (rv=export_pwm(channel, 1)) )
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{
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log_error("export PWM channel[%d] failed, rv=%d\n", channel, rv);
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return rv;
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}
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if( (rv=config_pwm(channel, freq, duty)) )
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{
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log_error("config PWM channel[%d] failed, rv=%d\n", channel, rv);
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return rv;
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}
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log_debug("config pwm%d with freq[%d] duty[%d] okay\n", channel, freq, duty);
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return 0;
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}
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int turn_pwm(int channel, int status)
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{
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int fd;
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char buf[32];
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char path[256];
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if( !check_pwm(channel) )
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return -1;
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/* open PWM enable file and enable(1)/disable(0) it */
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snprintf(path, sizeof(path), "%s/pwm%d/enable", PWMCHIP_PATH, channel);
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if( (fd=open(path, O_WRONLY)) < 0 )
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{
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log_error("open '%s' failed: %s\n", path, strerror(errno));
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return -3;
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}
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snprintf(buf, sizeof(buf), "%d", status?1:0);
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write(fd, buf, strlen(buf));
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log_debug("pwm[%d] %s\n", channel, status?"enable":"disable");
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return 0;
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}
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int term_pwm(int channel)
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{
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if( !check_pwm(channel) )
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return 0;
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turn_pwm(channel, DISABLE);
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export_pwm(channel, 0);
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return 0;
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}
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int turn_beep(int times)
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{
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int rv;
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/* stop beeper beep */
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if(times == 0)
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{
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log_debug("Stop beeper\n");
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term_pwm(CHN_BEEPER);
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return 0;
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}
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rv = init_pwm(CHN_BEEPER, FRQ_BEEPER, 50);
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if(rv < 0)
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{
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log_error("Initial beeper pwm[%d] failed, rv=%d\n", CHN_BEEPER);
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return -2;
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}
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/* turn beeper beep ceaselessly */
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if( times < 0)
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{
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turn_pwm(CHN_BEEPER, ENABLE);
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return 0;
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}
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while( times-- )
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{
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turn_pwm(CHN_BEEPER, ENABLE);
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msleep(800);
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turn_pwm(CHN_BEEPER, DISABLE);
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msleep(800);
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}
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term_pwm(CHN_BEEPER);
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return 0;
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}
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