From c34d95b74cc57dc709a6ef4d953bc2dd0e699881 Mon Sep 17 00:00:00 2001 From: youngkin Date: Wed, 1 Dec 2021 22:14:59 +0000 Subject: [PATCH] add an example to test PWM balanced mode --- examples/pwmbalanced/pwm.go | 44 ++++++++++++++++++ rpio.go | 90 ++++++++++++++++++------------------- 2 files changed, 89 insertions(+), 45 deletions(-) create mode 100644 examples/pwmbalanced/pwm.go diff --git a/examples/pwmbalanced/pwm.go b/examples/pwmbalanced/pwm.go new file mode 100644 index 0000000..7a0841c --- /dev/null +++ b/examples/pwmbalanced/pwm.go @@ -0,0 +1,44 @@ +/* + +A PWM example by @youngkin, using the go-rpio library + +Fades a PWM hardware pin in and out using PWM mode balanced (vs. markspace) +*/ + +package main + +import ( + "os" + "time" + + "github.com/stianeikeland/go-rpio/v4" +) + +func main() { + err := rpio.Open() + if err != nil { + os.Exit(1) + } + defer rpio.Close() + + pin := rpio.Pin(19) + pin.Mode(rpio.Pwm) + pin.Freq(64000) + pin.DutyCycleWithPwmMode(0, 32, rpio.Balanced) + // the LED will be blinking at 2000Hz + // (source frequency divided by cycle length => 64000/32 = 2000) + + // five times smoothly fade in and out + for i := 0; i < 5; i++ { + for i := uint32(0); i < 32; i++ { // increasing brightness + pin.DutyCycleWithPwmMode(i, 32, rpio.Balanced) + time.Sleep(time.Second / 32) + } + for i := uint32(32); i > 0; i-- { // decreasing brightness + pin.DutyCycleWithPwmMode(i, 32, rpio.Balanced) + time.Sleep(time.Second / 32) + } + } + + pin.DutyCycleWithPwmMode(0, 32, rpio.Balanced) +} diff --git a/rpio.go b/rpio.go index bcfae39..557e993 100644 --- a/rpio.go +++ b/rpio.go @@ -3,65 +3,65 @@ Package rpio provides GPIO access on the Raspberry PI without any need for external c libraries (eg. WiringPi or BCM2835). Supports simple operations such as: - - Pin mode/direction (input/output/clock/pwm,alt0,alt1,alt2,alt3,alt4,alt5) - - Pin write (high/low) - - Pin read (high/low) - - Pin edge detection (no/rise/fall/any) - - Pull up/down/off + - Pin mode/direction (input/output/clock/pwm,alt0,alt1,alt2,alt3,alt4,alt5) + - Pin write (high/low) + - Pin read (high/low) + - Pin edge detection (no/rise/fall/any) + - Pull up/down/off Also clock/pwm related oparations: - - Set Clock frequency - - Set Duty cycle + - Set Clock frequency + - Set Duty cycle And SPI oparations: - - SPI transmit/recieve/exchange bytes - - Chip select - - Set speed + - SPI transmit/recieve/exchange bytes + - Set speed + - Chip select Example of use: - rpio.Open() - defer rpio.Close() + rpio.Open() + defer rpio.Close() - pin := rpio.Pin(4) - pin.Output() + pin := rpio.Pin(4) + pin.Output() - for { - pin.Toggle() - time.Sleep(time.Second) - } + for { + pin.Toggle() + time.Sleep(time.Second) + } The library use the raw BCM2835 pinouts, not the ports as they are mapped on the output pins for the raspberry pi, and not the wiringPi convention. - Rev 2 and 3 Raspberry Pi Rev 1 Raspberry Pi (legacy) - +-----+---------+----------+---------+-----+ +-----+--------+----------+--------+-----+ - | BCM | Name | Physical | Name | BCM | | BCM | Name | Physical | Name | BCM | - +-----+---------+----++----+---------+-----+ +-----+--------+----++----+--------+-----+ - | | 3.3v | 1 || 2 | 5v | | | | 3.3v | 1 || 2 | 5v | | - | 2 | SDA 1 | 3 || 4 | 5v | | | 0 | SDA | 3 || 4 | 5v | | - | 3 | SCL 1 | 5 || 6 | 0v | | | 1 | SCL | 5 || 6 | 0v | | - | 4 | GPIO 7 | 7 || 8 | TxD | 14 | | 4 | GPIO 7 | 7 || 8 | TxD | 14 | - | | 0v | 9 || 10 | RxD | 15 | | | 0v | 9 || 10 | RxD | 15 | - | 17 | GPIO 0 | 11 || 12 | GPIO 1 | 18 | | 17 | GPIO 0 | 11 || 12 | GPIO 1 | 18 | - | 27 | GPIO 2 | 13 || 14 | 0v | | | 21 | GPIO 2 | 13 || 14 | 0v | | - | 22 | GPIO 3 | 15 || 16 | GPIO 4 | 23 | | 22 | GPIO 3 | 15 || 16 | GPIO 4 | 23 | - | | 3.3v | 17 || 18 | GPIO 5 | 24 | | | 3.3v | 17 || 18 | GPIO 5 | 24 | - | 10 | MOSI | 19 || 20 | 0v | | | 10 | MOSI | 19 || 20 | 0v | | - | 9 | MISO | 21 || 22 | GPIO 6 | 25 | | 9 | MISO | 21 || 22 | GPIO 6 | 25 | - | 11 | SCLK | 23 || 24 | CE0 | 8 | | 11 | SCLK | 23 || 24 | CE0 | 8 | - | | 0v | 25 || 26 | CE1 | 7 | | | 0v | 25 || 26 | CE1 | 7 | - | 0 | SDA 0 | 27 || 28 | SCL 0 | 1 | +-----+--------+----++----+--------+-----+ - | 5 | GPIO 21 | 29 || 30 | 0v | | - | 6 | GPIO 22 | 31 || 32 | GPIO 26 | 12 | - | 13 | GPIO 23 | 33 || 34 | 0v | | - | 19 | GPIO 24 | 35 || 36 | GPIO 27 | 16 | - | 26 | GPIO 25 | 37 || 38 | GPIO 28 | 20 | - | | 0v | 39 || 40 | GPIO 29 | 21 | - +-----+---------+----++----+---------+-----+ + Rev 2 and 3 Raspberry Pi Rev 1 Raspberry Pi (legacy) + +-----+---------+----------+---------+-----+ +-----+--------+----------+--------+-----+ + | BCM | Name | Physical | Name | BCM | | BCM | Name | Physical | Name | BCM | + +-----+---------+----++----+---------+-----+ +-----+--------+----++----+--------+-----+ + | | 3.3v | 1 || 2 | 5v | | | | 3.3v | 1 || 2 | 5v | | + | 2 | SDA 1 | 3 || 4 | 5v | | | 0 | SDA | 3 || 4 | 5v | | + | 3 | SCL 1 | 5 || 6 | 0v | | | 1 | SCL | 5 || 6 | 0v | | + | 4 | GPIO 7 | 7 || 8 | TxD | 14 | | 4 | GPIO 7 | 7 || 8 | TxD | 14 | + | | 0v | 9 || 10 | RxD | 15 | | | 0v | 9 || 10 | RxD | 15 | + | 17 | GPIO 0 | 11 || 12 | GPIO 1 | 18 | | 17 | GPIO 0 | 11 || 12 | GPIO 1 | 18 | + | 27 | GPIO 2 | 13 || 14 | 0v | | | 21 | GPIO 2 | 13 || 14 | 0v | | + | 22 | GPIO 3 | 15 || 16 | GPIO 4 | 23 | | 22 | GPIO 3 | 15 || 16 | GPIO 4 | 23 | + | | 3.3v | 17 || 18 | GPIO 5 | 24 | | | 3.3v | 17 || 18 | GPIO 5 | 24 | + | 10 | MOSI | 19 || 20 | 0v | | | 10 | MOSI | 19 || 20 | 0v | | + | 9 | MISO | 21 || 22 | GPIO 6 | 25 | | 9 | MISO | 21 || 22 | GPIO 6 | 25 | + | 11 | SCLK | 23 || 24 | CE0 | 8 | | 11 | SCLK | 23 || 24 | CE0 | 8 | + | | 0v | 25 || 26 | CE1 | 7 | | | 0v | 25 || 26 | CE1 | 7 | + | 0 | SDA 0 | 27 || 28 | SCL 0 | 1 | +-----+--------+----++----+--------+-----+ + | 5 | GPIO 21 | 29 || 30 | 0v | | + | 6 | GPIO 22 | 31 || 32 | GPIO 26 | 12 | + | 13 | GPIO 23 | 33 || 34 | 0v | | + | 19 | GPIO 24 | 35 || 36 | GPIO 27 | 16 | + | 26 | GPIO 25 | 37 || 38 | GPIO 28 | 20 | + | | 0v | 39 || 40 | GPIO 29 | 21 | + +-----+---------+----++----+---------+-----+ See the spec for full details of the BCM2835 controller: - https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2835/BCM2835-ARM-Peripherals.pdf - and https://elinux.org/BCM2835_datasheet_errata - for errors in that spec +https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2835/BCM2835-ARM-Peripherals.pdf +and https://elinux.org/BCM2835_datasheet_errata - for errors in that spec Changes to support the BCM2711, used on the Raspberry Pi 4, were cribbed from https://github.com/RPi-Distro/raspi-gpio/