PWM in NanoPi M4 - Revision history

Admin: /* PWM */

2020-04-03T16:59:18Z

PWM

Admin at 08:49, 18 March 2020

2020-03-18T08:49:29Z

Admin at 16:31, 6 March 2020

2020-03-06T16:31:46Z

Admin: Created page with "== Preparing NanoPi M4 for PWM == === Installation === Download the file rk3399-eflasher-friendlycore-bionic-4.4-arm64-20191227.img from the FriendlyElec repository. Then,..."

2020-02-24T17:12:58Z

Created page with "== Preparing NanoPi M4 for PWM == === Installation === Download the file rk3399-eflasher-friendlycore-bionic-4.4-arm64-20191227.img from the FriendlyElec repository. Then,..."

New page

== Preparing NanoPi M4 for PWM ==

=== Installation ===

Download the file
rk3399-eflasher-friendlycore-bionic-4.4-arm64-20191227.img
from the FriendlyElec repository.

Then, install it in a 16GB flash memory through balenaEtcher or equivalent software.

You need to connect USB Keyboard and Mouse, and an HDMI monitor. Select the OS and click on Install.

The OS will be installed in the eMMC card (it's not included in the board, so it's necessary to buy as option).

=== Test ===

Connect the USB2Serial to the 4pins between the USB ports. It's necessary to cut a slice because it doesn't fit properly. The black wire is the most external.

Configuration:

1500000 Baud
8 Data bits
1 Stop bit
Parity None
Flow Control XON/XOFF

Username root, password fa .

=== PWM ===

Stop and disable the pwm-fan service

service pwm-fan stop
systemctl disable pwm-fan

Then, start the PWM

echo 0 > /sys/class/pwm/pwmchip1/export
echo normal > /sys/class/pwm/pwmchip1/pwm0/polarity
echo 100000 > /sys/class/pwm/pwmchip1/pwm0/period
echo 5000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle
echo 1 /sys/class/pwm/pwmchip1/pwm0/enable

It's possible to test it connecting the PINS 19 (Ground) and 23 (PWM1) of the 24-Pins secondary header to a simple handheld oscilliscope. It will show a PWM signal of about 2V.

← Older revision		Revision as of 08:49, 18 March 2020
Line 1:		Line 1:
	== Preparing NanoPi M4 for PWM ==		== Preparing NanoPi M4 for PWM ==
		+
		+	=== Wiring ===
		+
		+	[[File:Review-NPIM4p31.jpg]]

	=== Installation ===		=== Installation ===

← Older revision		Revision as of 16:31, 6 March 2020
Line 43:		Line 43:

	It's possible to test it connecting the PINS 19 (Ground) and 23 (PWM1) of the 24-Pins secondary header to a simple handheld oscilliscope. It will show a PWM signal of about 2V.		It's possible to test it connecting the PINS 19 (Ground) and 23 (PWM1) of the 24-Pins secondary header to a simple handheld oscilliscope. It will show a PWM signal of about 2V.
		+
		+	=== Sowtware PWM ===
		+
		+	Create the followinf file:
		+
		+	#include <errno.h>
		+	#include <fcntl.h>
		+	#include <stdio.h>
		+	#include <stdlib.h>
		+	#include <sys/stat.h>
		+	#include <sys/types.h>
		+	#include <unistd.h>
		+
		+	int main() {
		+	int fd = open("/sys/class/gpio/gpio9/value", O_WRONLY);
		+	if (fd == -1) {
		+	perror("Unable to open /sys/class/gpio/gpio9/value");
		+	exit(1);
		+	}
		+	for (int i = 0; i < 10000; i++) {
		+	if (write(fd, "1", 1) != 1) {
		+	perror("Error writing to /sys/class/gpio/gpio9/value");
		+	exit(1);
		+	}
		+	usleep(400);
		+	if (write(fd, "0", 1) != 1) {
		+	perror("Error writing to /sys/class/gpio/gpio9/value");
		+	exit(1);
		+	}
		+	usleep(3600);
		+	}
		+	close(fd);
		+	}
		+
		+	And compile it
		+
		+	gcc -o pwm9 pwm.c
		+
		+	Launch and test
		+
		+	./pwm9

@@ Line 41: / Line 41: @@
   echo 0 > /sys/class/pwm/pwmchip1/export
   echo normal > /sys/class/pwm/pwmchip1/pwm0/polarity
   echo 5000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle
-  echo 1 /sys/class/pwm/pwmchip1/pwm0/enable
+  echo 1 > /sys/class/pwm/pwmchip1/pwm0/enable
 It's possible to test it connecting the PINS 19 (Ground) and 23 (PWM1) of the 24-Pins secondary header to a simple handheld oscilliscope. It will show a PWM signal of about 2V.