f:id:pongsuke:20191203104147j:plain

ソフトウェアPWMの場合、処理が重かったり、他のUSB機器の影響？で、動作が不安定になりがちです。
具体的には、ガタガタしたりします。

まぁ、そりゃそうだろうという感じです。

そこで、PWM に特化した PIN を使用します。
hardware pwm と呼ばれています。

データシートより

f:id:pongsuke:20191203102402p:plain — Datasheet

みると、確かにGPIO12,13 は、PWM0, PWM1 となっており、特別なようだ。

$ gpio readall
Oops - unable to determine board type... model: 17

$ gpio -v
gpio version: 2.50
Copyright (c) 2012-2018 Gordon Henderson
This is free software with ABSOLUTELY NO WARRANTY.
For details type: gpio -warranty

Raspberry Pi Details:
  Type: Unknown17, Revision: 01, Memory: 0MB, Maker: Sony 
  * Device tree is enabled.
  *--> Raspberry Pi 4 Model B Rev 1.1
  * This Raspberry Pi supports user-level GPIO access.

wiringPi updated to 2.52 for the Raspberry Pi 4B | Wiring Pi

$ cd /tmp
$ wget https://project-downloads.drogon.net/wiringpi-latest.deb
$ sudo dpkg -i wiringpi-latest.deb

$ gpio -v
gpio version: 2.52
Copyright (c) 2012-2018 Gordon Henderson
This is free software with ABSOLUTELY NO WARRANTY.
For details type: gpio -warranty

Raspberry Pi Details:
  Type: Pi 4B, Revision: 01, Memory: 4096MB, Maker: Sony 
  * Device tree is enabled.
  *--> Raspberry Pi 4 Model B Rev 1.1
  * This Raspberry Pi supports user-level GPIO access.

$ gpio readall
 +-----+-----+---------+------+---+---Pi 4B--+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 |     |     |    3.3v |      |   |  1 || 2  |   |      | 5v      |     |     |
 |   2 |   8 |   SDA.1 |   IN | 1 |  3 || 4  |   |      | 5v      |     |     |
 |   3 |   9 |   SCL.1 |   IN | 1 |  5 || 6  |   |      | 0v      |     |     |
 |   4 |   7 | GPIO. 7 |   IN | 1 |  7 || 8  | 1 | IN   | TxD     | 15  | 14  |
 |     |     |      0v |      |   |  9 || 10 | 1 | IN   | RxD     | 16  | 15  |
 |  17 |   0 | GPIO. 0 |   IN | 0 | 11 || 12 | 1 | IN   | GPIO. 1 | 1   | 18  |
 |  27 |   2 | GPIO. 2 |   IN | 0 | 13 || 14 |   |      | 0v      |     |     |
 |  22 |   3 | GPIO. 3 |   IN | 0 | 15 || 16 | 0 | IN   | GPIO. 4 | 4   | 23  |
 |     |     |    3.3v |      |   | 17 || 18 | 0 | IN   | GPIO. 5 | 5   | 24  |
 |  10 |  12 |    MOSI |   IN | 0 | 19 || 20 |   |      | 0v      |     |     |
 |   9 |  13 |    MISO |   IN | 0 | 21 || 22 | 0 | IN   | GPIO. 6 | 6   | 25  |
 |  11 |  14 |    SCLK |   IN | 0 | 23 || 24 | 1 | IN   | CE0     | 10  | 8   |
 |     |     |      0v |      |   | 25 || 26 | 1 | IN   | CE1     | 11  | 7   |
 |   0 |  30 |   SDA.0 |   IN | 1 | 27 || 28 | 1 | IN   | SCL.0   | 31  | 1   |
 |   5 |  21 | GPIO.21 |   IN | 1 | 29 || 30 |   |      | 0v      |     |     |
 |   6 |  22 | GPIO.22 |   IN | 1 | 31 || 32 | 0 | IN   | GPIO.26 | 26  | 12  |
 |  13 |  23 | GPIO.23 |   IN | 0 | 33 || 34 |   |      | 0v      |     |     |
 |  19 |  24 | GPIO.24 |   IN | 0 | 35 || 36 | 0 | IN   | GPIO.27 | 27  | 16  |
 |  26 |  25 | GPIO.25 |   IN | 0 | 37 || 38 | 0 | IN   | GPIO.28 | 28  | 20  |
 |     |     |      0v |      |   | 39 || 40 | 0 | IN   | GPIO.29 | 29  | 21  |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+---Pi 4B--+---+------+---------+-----+-----+

動作テスト

SG92, SG90 を２つ制御してみる。
制御電圧 5.0V に足りませんが、動きます。

サービスを立ち上げて、、、

$ sudo pigpiod

コマンド実行

import pigpio
import time

gpio_pin0 = 12
gpio_pin1 = 13

pi = pigpio.pi()
pi.set_mode(gpio_pin0, pigpio.OUTPUT)
pi.set_mode(gpio_pin1, pigpio.OUTPUT)

# SP92 min 25000, mid 72500 max 120000

# GPIO12: Hz、duty比
pi.hardware_PWM(gpio_pin0, 50, 72500)
time.sleep(0.5)
pi.hardware_PWM(gpio_pin0, 50, 100000)
time.sleep(0.5)
pi.hardware_PWM(gpio_pin0, 50, 72500)
time.sleep(0.5)
pi.hardware_PWM(gpio_pin0, 50, 50000)
time.sleep(0.5)
pi.hardware_PWM(gpio_pin0, 50, 72500)
time.sleep(0.5)

# GPIO13: Hz、duty比
pi.hardware_PWM(gpio_pin1, 50, 48750)
time.sleep(0.5)
pi.hardware_PWM(gpio_pin1, 50, 25000)
time.sleep(0.5)
pi.hardware_PWM(gpio_pin1, 50, 48750)
time.sleep(0.5)
pi.hardware_PWM(gpio_pin1, 50, 60000)
time.sleep(0.5)
pi.hardware_PWM(gpio_pin1, 50, 48750)
time.sleep(0.5)

time.sleep(1)

pi.set_mode(gpio_pin0, pigpio.INPUT)
pi.set_mode(gpio_pin1, pigpio.INPUT)
pi.stop()