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address code review comments
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youngkin
parent
02c0360e26
commit
915fc229cf
135
rpio.go
135
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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- Chip select
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- Set speed
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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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@ -148,8 +148,8 @@ const (
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// Which PWM algorithm to use, Balanced or Mark/Space
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const (
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Balanced = iota
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MarkSpace
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Balanced = true
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MarkSpace = false
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)
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// Pull Up / Down / Off
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@ -228,9 +228,10 @@ func (pin Pin) DutyCycle(dutyLen, cycleLen uint32) {
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SetDutyCycle(pin, dutyLen, cycleLen)
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}
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// DutyCycleMsen: Set duty cycle for Pwm pin (see doc of SetDutyCycle)
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func (pin Pin) DutyCycleMsen(dutyLen, cycleLen, msen uint32) {
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SetDutyCycleMsen(pin, dutyLen, cycleLen, msen)
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// DutyCycleWithPwmMode: Set duty cycle for Pwm pin while also specifying which PWM
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// mode to use, Balanced or MarkSpace (see doc of SetDutyCycleWithPwmMode)
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func (pin Pin) DutyCycleWithPwmMode(dutyLen, cycleLen uint32, mode bool) {
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SetDutyCycleWithPwmMode(pin, dutyLen, cycleLen, mode)
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}
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// Mode: Set pin Mode
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@ -638,17 +639,20 @@ func SetFreq(pin Pin, freq int) {
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// The channels are:
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// channel 1 (pwm0) for pins 12, 18, 40
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// channel 2 (pwm1) for pins 13, 19, 41, 45.
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//
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// NOTE without root permission this function will simply do nothing successfully
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func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) {
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SetDutyCycleMsen(pin, dutyLen, cycleLen, 1) // Default PWM algorithm is Mark/Space, msen = 1
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SetDutyCycleWithPwmMode(pin, dutyLen, cycleLen, MarkSpace)
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}
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// SetDutyCycleMsen extends SetDutyCycle to allow for the specification of the PWM
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// algorithm to be used, Balanced or Mark/Space. 'msen' is used to indicate which
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// PWM algorithm to use. The constants Balanced or Markspace should be used as the
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// value. See 'SetDutyCycle(pin, dutyLen, cycleLen)' above for more information
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// regarding how to use 'SetDutyCycleMsen()'
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func SetDutyCycleMsen(pin Pin, dutyLen, cycleLen, msen uint32) {
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// SetDutyCycleWithPwmMode extends SetDutyCycle to allow for the specification of the PWM
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// algorithm to be used, Balanced or Mark/Space. The constants Balanced or MarkSpace
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// as the value. See 'SetDutyCycle(pin, dutyLen, cycleLen)' above for more information
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// regarding how to use 'SetDutyCycleWithPwmMode()'.
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//
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// NOTE without root permission this function will simply do nothing successfully
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func SetDutyCycleWithPwmMode(pin Pin, dutyLen, cycleLen uint32, mode bool) {
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const pwmCtlReg = 0
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var (
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pwmDatReg uint
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@ -673,17 +677,24 @@ func SetDutyCycleMsen(pin Pin, dutyLen, cycleLen, msen uint32) {
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const ctlMask = 255 // ctl setting has 8 bits for each channel
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const pwen = 1 << 0 // enable pwm
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msen = msen << 7
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var msen uint32 = 0
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// The MSEN1 field in the CTL register is at offset 7. This block starts with the assumption
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// that 'msen' will be associated with channel 'pwm0'. If this is not the case, 'msen' will
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// be further shifted in the next code block below to the MSEN2 field at offset 15.
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if mode == MarkSpace {
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msen = 1 << 7
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}
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// reset settings
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// Shifting 'pwen' and 'msen' puts the associated values at the correct offset within the CTL
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// register ('pwmCtlReg'). In addition, 'msen' is associated with a PWM channel depending on the
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// value of 'pin' (see above). 'msen' will either stay at offset 7, as set above for channel 'pwm0',
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// or be shifted 8 bits if the the associated 'pin' is on channel 'pwm1'.
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pwmMem[pwmCtlReg] = pwmMem[pwmCtlReg]&^(ctlMask<<shift) | msen<<shift | pwen<<shift
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// set duty cycle
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pwmMem[pwmDatReg] = dutyLen
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pwmMem[pwmRngReg] = cycleLen
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time.Sleep(time.Microsecond * 10)
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// NOTE without root permission this changes will simply do nothing successfully
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}
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// StopPwm: Stop pwm for both channels
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