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Hardware PWM Controller for the Raspberry Pi 4 Case Fan
Raw
Makefile
CC = gcc
RM = rm -f
INSTRUMENT_FOR_PROMETHEUS := false
ifeq ($(INSTRUMENT_FOR_PROMETHEUS),true)
CFLAGS = -Wall -DINSTRUMENT_FOR_PROMETHEUS
LIBS = -lbcm2835 -lprom -lpromhttp -lmicrohttpd
else
CFLAGS = -Wall
LIBS = -lbcm2835
endif
TARGET = pi_fan_hwpwm
all: $(TARGET)
$(TARGET): $(TARGET).c Makefile
$(CC) $(CFLAGS) -o $(TARGET) $(TARGET).c $(LIBS)
install: $(TARGET)
install $(TARGET) /usr/local/sbin
cp $(TARGET).service /etc/systemd/system/
systemctl enable $(TARGET)
! systemctl is-active --quiet $(TARGET) || systemctl stop $(TARGET)
systemctl start $(TARGET)
uninstall: clean
systemctl stop $(TARGET)
systemctl disable $(TARGET)
$(RM) /usr/local/sbin/$(TARGET)
$(RM) /etc/systemd/system/$(TARGET).service
$(RM) /run/$(TARGET).*
@echo
@echo "To remove the source directory"
@echo " $$ cd && rm -rf ${CURDIR}"
@echo
clean:
$(RM) $(TARGET)
Raw
pi_fan_hwpwm.c
/*
/
/ pi_fan_hwpwm.c, [email protected] 12/2020, no license
/ latest version: https://gist.github.com/alwynallan/1c13096c4cd675f38405702e89e0c536
/
/ Need http://www.airspayce.com/mikem/bcm2835/index.html
/
/ Compile $ gcc -Wall pi_fan_hwpwm.c -lbcm2835 -o pi_fan_hwpwm
/
/ Disable $ sudo nano /boot/config.txt [Raspbian, or use GUI]
/ $ sudo nano /boot/firmware/usercfg.txt [Ubuntu]
/ # dtoverlay=gpio-fan,gpiopin=14,temp=80000 <- commented out, reboot
/ enable_uart=0 <- needed? not Ubuntu
/ dtparam=audio=off <- needed? not Ubuntu
/ dtparam=i2c_arm=off <- needed? not Ubuntu
/ dtparam=spi=off <- needed? not Ubuntu
/
/ Run $ sudo ./pi_fan_hwpwm -v
/
/ Forget $ sudo ./pi_fan_hwpwm &
/ $ disown -a
/
*/
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdarg.h>
#include <bcm2835.h>
//#define INSTRUMENT_FOR_PROMETHEUS do this in the Makefile
#ifdef INSTRUMENT_FOR_PROMETHEUS
// https://github.com/digitalocean/prometheus-client-c
#define PROM_PORT 8764
#include <signal.h>
#include "microhttpd.h"
#include "prom.h"
#include "promhttp.h"
prom_counter_t *pi_fan_hwpwm_loops;
prom_gauge_t *pi_fan_hwpwm_temp;
prom_gauge_t *pi_fan_hwpwm_pwm;
#endif //INSTRUMENT_FOR_PROMETHEUS
#define PWM_PIN 0 // default, uses both GPIO 13 and GPIO 18
#define HIGH_TEMP 80.
#define ON_TEMP 65.
#define OFF_TEMP 60.
#define MIN_FAN 150
#define KICK_FAN 200
#define MAX_FAN 480
unsigned pin = PWM_PIN;
int verbose = 0;
int fan_state = 0;
double temp = 25.0;
pid_t global_pid;
int pwm_level = -555;
void usage()
{
fprintf
(stderr,
"\n" \
"Usage: sudo ./pi_fan_hwpwm [OPTION]...\n" \
"\n" \
" -g <n> Use GPIO n for fan's PWM input, default 0 (both).\n" \
" Only hardware PWM capable GPIO 18 and GPIO 13 are present on\n" \
" the RasPi 4B pin header, and only GPIO 18 can be used with\n" \
" the unmodified case fan.\n" \
" -v Verbose output\n" \
"\n"
);
}
void fatal(int show_usage, char *fmt, ...) {
char buf[128];
va_list ap;
va_start(ap, fmt);
vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
fprintf(stderr, "%s\n", buf);
if (show_usage) usage();
fflush(stderr);
exit(EXIT_FAILURE);
}
void run_write(const char *fname, const char *data) {
// https://opensource.com/article/19/4/interprocess-communication-linux-storage
struct flock lock;
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
lock.l_pid = global_pid;
int fd;
if ((fd = open(fname, O_RDWR | O_CREAT, 0666)) < 0)
fatal(0, "failed to open %s for writing", fname);
if (fcntl(fd, F_SETLK, &lock) < 0)
fatal(0, "fcntl failed to get lock on %s", fname);
if (ftruncate(fd, 0) < 0)
fatal(0, "truncate failed to on %s", fname);
write(fd, data, strlen(data));
close(fd);
}
void PWM_out(int level) {
if(level > pwm_level && (level - pwm_level) < 5) return;
if(level < pwm_level && (pwm_level - level) < 10) return;
if(level != pwm_level) {
if(pin == 0 || pin == 13) bcm2835_pwm_set_data(1, level);
if(pin == 0 || pin == 18) bcm2835_pwm_set_data(0, level);
pwm_level = level;
}
}
void fan_loop(void) {
if(!fan_state && (temp > ON_TEMP)) {
PWM_out(KICK_FAN);
fan_state = 1;
return;
}
if(fan_state && (temp < OFF_TEMP)) {
PWM_out(0);
fan_state = 0;
return;
}
if(fan_state) {
unsigned out = (double) MIN_FAN + (temp - OFF_TEMP) / (HIGH_TEMP - OFF_TEMP) * (double)(MAX_FAN - MIN_FAN);
if(out > MAX_FAN) out = MAX_FAN;
PWM_out(out);
}
}
#ifdef INSTRUMENT_FOR_PROMETHEUS
void ae1() {
prom_collector_registry_destroy(PROM_COLLECTOR_REGISTRY_DEFAULT);
}
struct MHD_Daemon *mhdDaemon;
void ae2() {
MHD_stop_daemon(mhdDaemon);
}
#endif //INSTRUMENT_FOR_PROMETHEUS
int main(int argc, char *argv[]) {
int opt;
unsigned loop = 0;
int t;
FILE *ft;
char buf[100];
while ((opt = getopt(argc, argv, "g:v")) != -1) {
switch (opt) {
case 'g':
pin = atoi(optarg);
if(pin != 0 && pin != 13 && pin != 18) fatal(0, "Invalid GPIO");
break;
case 'v':
verbose = 1;
break;
default:
usage();
exit(EXIT_FAILURE);
}
}
if(optind != argc) fatal(1, "optind=%d argc=%d Unrecognized parameter %s", optind, argc, argv[optind]);
global_pid = getpid();
sprintf(buf, "%d\n", global_pid);
run_write("/run/pi_fan_hwpwm.pid", buf);
if(!bcm2835_init()) fatal(0, "bcm2835_init() failed");
if(pin==0 || pin==13) bcm2835_gpio_fsel(13, BCM2835_GPIO_FSEL_ALT0);
if(pin==0 || pin==18) bcm2835_gpio_fsel(18, BCM2835_GPIO_FSEL_ALT5);
bcm2835_pwm_set_clock(2); // 19.2 / 2 MHz
if(pin==0 || pin==13) bcm2835_pwm_set_mode(1, 1, 1);
if(pin==0 || pin==13) bcm2835_pwm_set_range(1, 480);
if(pin==0 || pin==18) bcm2835_pwm_set_mode(0, 1, 1);
if(pin==0 || pin==18) bcm2835_pwm_set_range(0, 480);
PWM_out(0);
#ifdef INSTRUMENT_FOR_PROMETHEUS
prom_collector_registry_default_init();
pi_fan_hwpwm_loops = prom_collector_registry_must_register_metric(
prom_counter_new("pi_fan_hwpwm_loops", "Control loop counter.", 0, NULL));
pi_fan_hwpwm_temp = prom_collector_registry_must_register_metric(
prom_gauge_new("pi_fan_hwpwm_temp", "Core temperature in Celsius.", 0, NULL));
pi_fan_hwpwm_pwm = prom_collector_registry_must_register_metric(
prom_gauge_new("pi_fan_hwpwm_pwm", "Fan speed PWM in percent.", 0, NULL));
promhttp_set_active_collector_registry(NULL);
atexit(ae1);
mhdDaemon = promhttp_start_daemon(MHD_USE_SELECT_INTERNALLY, PROM_PORT, NULL, NULL);
if (mhdDaemon == NULL) exit(EXIT_FAILURE);
else atexit(ae2);
#endif //INSTRUMENT_FOR_PROMETHEUS
while(1) {
loop++;
ft = fopen("/sys/class/thermal/thermal_zone0/temp", "r");
fscanf(ft, "%d", &t);
fclose(ft);
temp = 0.0001 * (double)t + 0.9 * temp;
if((loop%4) == 0) { // every second
fan_loop();
sprintf(buf, "%u, %.2f, %.1f\n", loop/4, temp, (float)pwm_level/(float)MAX_FAN*100.);
run_write("/run/pi_fan_hwpwm.state", buf);
if(verbose) fputs(buf, stdout);
#ifdef INSTRUMENT_FOR_PROMETHEUS
prom_counter_inc(pi_fan_hwpwm_loops, NULL);
prom_gauge_set(pi_fan_hwpwm_temp, temp, NULL);
prom_gauge_set(pi_fan_hwpwm_pwm, (double)pwm_level/(double)MAX_FAN*100., NULL);
#endif //INSTRUMENT_FOR_PROMETHEUS
}
usleep(250000);
}
exit(EXIT_SUCCESS);
}
Raw
pi_fan_hwpwm.service
[Unit]
Description=Hardware PWM control for Raspberry Pi 4 Case Fan
After=syslog.target
[Service]
Type=simple
User=root
WorkingDirectory=/run
PIDFile=/run/pi_fan_hwpwm.pid
ExecStart=/usr/local/sbin/pi_fan_hwpwm
Restart=on-failure
[Install]
WantedBy=multi-user.target
@alwynallan
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Author

alwynallan commented Feb 24, 2022 •
edited
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I added code to instrument this tiny service for monitoring with Prometheus. Unless you're already using Prometheus/Grafana it's probably best to ignore this, and the default is to not use the code in this this update. To use it, get it running using my previous recipe, then

  $ sudo apt-get update
  $ sudo apt-get install ca-certificates curl gnupg lsb-release
  $ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
  $ echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
  $ sudo apt-get update
  $ sudo apt-get install docker-ce docker-ce-cli containerd.io
  $ sudo apt install cmake libmicrohttpd-dev
  $ cd
  $ git clone https://github.com/digitalocean/prometheus-client-c.git
  $ cd prometheus-client-c
  $ ./auto build
  $ sudo make
  $ sudo make install
  $ cd ~/1c13096c4cd675f38405702e89e0c536
  $ nano Makefile
    INSTRUMENT_FOR_PROMETHEUS := true
  $ make
  $ sudo make install
  $ curl localhost:8764/metrics

@josejsarmento
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josejsarmento commented Jul 19, 2022 •
edited
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Thank you so much for this! Worked perfectly for a 64-bit Ubuntu server Raspberry Pi 8GB. As for the Prometheus integration, should I first get Prometheus running via its docker image and target the port you specify here (8764) or is this prometheus-client-c a standalone version?

EDIT: It seems I can't build the Prometheus C client, it gave me a Make error on the step GOPATH in the Dockerfile:

+ GOPATH=/gopath /usr/local/go/bin/go get github.com/prometheus/prom2json
/bin/sh: 1: /usr/local/go/bin/go: Exec format error
The command '/bin/sh -c set -x &&     apt-get update && ... &&     chmod +x /entrypoint &&     GOPATH=/gopath /usr/local/go/bin/go get github.com/prometheus/prom2json && ... &&     rm -rf /var/lib/apt/lists/*' returned a non-zero code: 2
make: *** [Makefile:2: docker] Error 2

Check this to fix it

@vincentkenny01
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hi,
I am using RPI 4 8GB model headless with Raspberry Pi OS Lite 64bit installed. I have this fan installed and connected to GPIO 18 pin.
My system is up to date.
I can follow your guide up to this point
$ sudo apt install -y build-essential git stress-ng
$ cd
$ wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.68.tar.gz
$ tar zxvf bcm2835-1.68.tar.gz
$ cd bcm2835-1.68
$ ./configure
$ make
$ sudo make install
$ cd
$ git clone https://gist.github.com/1c13096c4cd675f38405702e89e0c536.git
$ cd 1c13096c4cd675f38405702e89e0c536

But when I follow the next step of make, I get the following error - " Makefile:19: *** missing separator (did you mean TAB instead of 8 spaces?). Stop."

I have tried a few times but I am kind of lost here on what to do next.

Is there an issue with the file/format or do you think I don't have the right hardware to follow this through?

Please let me know.

Best,
V

@josejsarmento
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josejsarmento commented Jul 19, 2022 •
edited
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But when I follow the next step of make, I get the following error - " Makefile:19: *** missing separator (did you mean TAB instead of 8 spaces?). Stop."

@vincentkenny01 I've had the same error, the Makefile here is erroneously indented with spaces instead of a tab. You must replace manually those spaces with tabs on the Makefile.

@vincentkenny01
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vincentkenny01 commented Jul 19, 2022 via email

@josejsarmento
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josejsarmento commented Jul 19, 2022 •
edited
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@vincentkenny010 You can check my fork of this gist, I have indented correctly the Makefile there.

I think a project such as this deserves its own repo on Github, don't you think @alwynallan ? It's a feature highly requested on the internet, and there's so few working and efficient implementations of this. A repo would allow for pull requests and for issues discussions such as these.

@vincentkenny01
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vincentkenny01 commented Jul 19, 2022 via email

@timrowledge
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timrowledge commented Oct 18, 2023 •
edited
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I've just updated a Pi4 to Bookworm and can't compile this because bcm2835.h is not found. Searching with
find / -mount -name bcm28*.h -print
says it isn't there for reals.
WTF?
Did I forget to install some prerequisite?

D'OH! Yes. Missed the entire wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.68.tar.gz thing etc. All done.

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