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https://github.com/stianeikeland/go-rpio.git
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add an example to test PWM balanced mode
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youngkin
parent
915fc229cf
commit
c34d95b74c
44
examples/pwmbalanced/pwm.go
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44
examples/pwmbalanced/pwm.go
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@ -0,0 +1,44 @@
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/*
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A PWM example by @youngkin, using the go-rpio library
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Fades a PWM hardware pin in and out using PWM mode balanced (vs. markspace)
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*/
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package main
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import (
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"os"
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"time"
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"github.com/stianeikeland/go-rpio/v4"
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)
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func main() {
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err := rpio.Open()
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if err != nil {
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os.Exit(1)
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}
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defer rpio.Close()
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pin := rpio.Pin(19)
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pin.Mode(rpio.Pwm)
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pin.Freq(64000)
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pin.DutyCycleWithPwmMode(0, 32, rpio.Balanced)
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// the LED will be blinking at 2000Hz
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// (source frequency divided by cycle length => 64000/32 = 2000)
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// five times smoothly fade in and out
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for i := 0; i < 5; i++ {
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for i := uint32(0); i < 32; i++ { // increasing brightness
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pin.DutyCycleWithPwmMode(i, 32, rpio.Balanced)
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time.Sleep(time.Second / 32)
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}
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for i := uint32(32); i > 0; i-- { // decreasing brightness
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pin.DutyCycleWithPwmMode(i, 32, rpio.Balanced)
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time.Sleep(time.Second / 32)
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}
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}
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pin.DutyCycleWithPwmMode(0, 32, rpio.Balanced)
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}
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90
rpio.go
90
rpio.go
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@ -3,65 +3,65 @@ Package rpio provides GPIO access on the Raspberry PI without any need
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for external c libraries (eg. WiringPi or BCM2835).
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Supports simple operations such as:
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- Pin mode/direction (input/output/clock/pwm,alt0,alt1,alt2,alt3,alt4,alt5)
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- Pin write (high/low)
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- Pin read (high/low)
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- Pin edge detection (no/rise/fall/any)
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- Pull up/down/off
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- Pin mode/direction (input/output/clock/pwm,alt0,alt1,alt2,alt3,alt4,alt5)
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- Pin write (high/low)
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- Pin read (high/low)
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- Pin edge detection (no/rise/fall/any)
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- Pull up/down/off
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Also clock/pwm related oparations:
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- Set Clock frequency
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- Set Duty cycle
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- Set Clock frequency
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- Set Duty cycle
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And SPI oparations:
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- SPI transmit/recieve/exchange bytes
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- Chip select
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- Set speed
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- SPI transmit/recieve/exchange bytes
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- Set speed
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- Chip select
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Example of use:
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rpio.Open()
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defer rpio.Close()
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rpio.Open()
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defer rpio.Close()
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pin := rpio.Pin(4)
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pin.Output()
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pin := rpio.Pin(4)
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pin.Output()
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for {
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pin.Toggle()
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time.Sleep(time.Second)
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}
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for {
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pin.Toggle()
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time.Sleep(time.Second)
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}
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The library use the raw BCM2835 pinouts, not the ports as they are mapped
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on the output pins for the raspberry pi, and not the wiringPi convention.
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Rev 2 and 3 Raspberry Pi Rev 1 Raspberry Pi (legacy)
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+-----+---------+----------+---------+-----+ +-----+--------+----------+--------+-----+
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| BCM | Name | Physical | Name | BCM | | BCM | Name | Physical | Name | BCM |
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+-----+---------+----++----+---------+-----+ +-----+--------+----++----+--------+-----+
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| | 3.3v | 1 || 2 | 5v | | | | 3.3v | 1 || 2 | 5v | |
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| 2 | SDA 1 | 3 || 4 | 5v | | | 0 | SDA | 3 || 4 | 5v | |
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| 3 | SCL 1 | 5 || 6 | 0v | | | 1 | SCL | 5 || 6 | 0v | |
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| 4 | GPIO 7 | 7 || 8 | TxD | 14 | | 4 | GPIO 7 | 7 || 8 | TxD | 14 |
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| | 0v | 9 || 10 | RxD | 15 | | | 0v | 9 || 10 | RxD | 15 |
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| 17 | GPIO 0 | 11 || 12 | GPIO 1 | 18 | | 17 | GPIO 0 | 11 || 12 | GPIO 1 | 18 |
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| 27 | GPIO 2 | 13 || 14 | 0v | | | 21 | GPIO 2 | 13 || 14 | 0v | |
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| 22 | GPIO 3 | 15 || 16 | GPIO 4 | 23 | | 22 | GPIO 3 | 15 || 16 | GPIO 4 | 23 |
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| | 3.3v | 17 || 18 | GPIO 5 | 24 | | | 3.3v | 17 || 18 | GPIO 5 | 24 |
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| 10 | MOSI | 19 || 20 | 0v | | | 10 | MOSI | 19 || 20 | 0v | |
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| 9 | MISO | 21 || 22 | GPIO 6 | 25 | | 9 | MISO | 21 || 22 | GPIO 6 | 25 |
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| 11 | SCLK | 23 || 24 | CE0 | 8 | | 11 | SCLK | 23 || 24 | CE0 | 8 |
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| | 0v | 25 || 26 | CE1 | 7 | | | 0v | 25 || 26 | CE1 | 7 |
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| 0 | SDA 0 | 27 || 28 | SCL 0 | 1 | +-----+--------+----++----+--------+-----+
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| 5 | GPIO 21 | 29 || 30 | 0v | |
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| 6 | GPIO 22 | 31 || 32 | GPIO 26 | 12 |
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| 13 | GPIO 23 | 33 || 34 | 0v | |
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| 19 | GPIO 24 | 35 || 36 | GPIO 27 | 16 |
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| 26 | GPIO 25 | 37 || 38 | GPIO 28 | 20 |
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| | 0v | 39 || 40 | GPIO 29 | 21 |
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+-----+---------+----++----+---------+-----+
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Rev 2 and 3 Raspberry Pi Rev 1 Raspberry Pi (legacy)
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+-----+---------+----------+---------+-----+ +-----+--------+----------+--------+-----+
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| BCM | Name | Physical | Name | BCM | | BCM | Name | Physical | Name | BCM |
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+-----+---------+----++----+---------+-----+ +-----+--------+----++----+--------+-----+
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| | 3.3v | 1 || 2 | 5v | | | | 3.3v | 1 || 2 | 5v | |
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| 2 | SDA 1 | 3 || 4 | 5v | | | 0 | SDA | 3 || 4 | 5v | |
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| 3 | SCL 1 | 5 || 6 | 0v | | | 1 | SCL | 5 || 6 | 0v | |
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| 4 | GPIO 7 | 7 || 8 | TxD | 14 | | 4 | GPIO 7 | 7 || 8 | TxD | 14 |
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| | 0v | 9 || 10 | RxD | 15 | | | 0v | 9 || 10 | RxD | 15 |
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| 17 | GPIO 0 | 11 || 12 | GPIO 1 | 18 | | 17 | GPIO 0 | 11 || 12 | GPIO 1 | 18 |
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| 27 | GPIO 2 | 13 || 14 | 0v | | | 21 | GPIO 2 | 13 || 14 | 0v | |
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| 22 | GPIO 3 | 15 || 16 | GPIO 4 | 23 | | 22 | GPIO 3 | 15 || 16 | GPIO 4 | 23 |
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| | 3.3v | 17 || 18 | GPIO 5 | 24 | | | 3.3v | 17 || 18 | GPIO 5 | 24 |
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| 10 | MOSI | 19 || 20 | 0v | | | 10 | MOSI | 19 || 20 | 0v | |
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| 9 | MISO | 21 || 22 | GPIO 6 | 25 | | 9 | MISO | 21 || 22 | GPIO 6 | 25 |
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| 11 | SCLK | 23 || 24 | CE0 | 8 | | 11 | SCLK | 23 || 24 | CE0 | 8 |
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| | 0v | 25 || 26 | CE1 | 7 | | | 0v | 25 || 26 | CE1 | 7 |
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| 0 | SDA 0 | 27 || 28 | SCL 0 | 1 | +-----+--------+----++----+--------+-----+
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| 5 | GPIO 21 | 29 || 30 | 0v | |
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| 6 | GPIO 22 | 31 || 32 | GPIO 26 | 12 |
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| 13 | GPIO 23 | 33 || 34 | 0v | |
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| 19 | GPIO 24 | 35 || 36 | GPIO 27 | 16 |
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| 26 | GPIO 25 | 37 || 38 | GPIO 28 | 20 |
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| | 0v | 39 || 40 | GPIO 29 | 21 |
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+-----+---------+----++----+---------+-----+
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See the spec for full details of the BCM2835 controller:
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https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2835/BCM2835-ARM-Peripherals.pdf
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and https://elinux.org/BCM2835_datasheet_errata - for errors in that spec
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https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2835/BCM2835-ARM-Peripherals.pdf
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and https://elinux.org/BCM2835_datasheet_errata - for errors in that spec
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Changes to support the BCM2711, used on the Raspberry Pi 4, were cribbed from https://github.com/RPi-Distro/raspi-gpio/
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