diff --git a/rpio.go b/rpio.go index 2e8898c..bcfae39 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 + - Chip select + - Set speed 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/ @@ -148,8 +148,8 @@ const ( // Which PWM algorithm to use, Balanced or Mark/Space const ( - Balanced = iota - MarkSpace + Balanced = true + MarkSpace = false ) // Pull Up / Down / Off @@ -228,9 +228,10 @@ func (pin Pin) DutyCycle(dutyLen, cycleLen uint32) { SetDutyCycle(pin, dutyLen, cycleLen) } -// DutyCycleMsen: Set duty cycle for Pwm pin (see doc of SetDutyCycle) -func (pin Pin) DutyCycleMsen(dutyLen, cycleLen, msen uint32) { - SetDutyCycleMsen(pin, dutyLen, cycleLen, msen) +// DutyCycleWithPwmMode: Set duty cycle for Pwm pin while also specifying which PWM +// mode to use, Balanced or MarkSpace (see doc of SetDutyCycleWithPwmMode) +func (pin Pin) DutyCycleWithPwmMode(dutyLen, cycleLen uint32, mode bool) { + SetDutyCycleWithPwmMode(pin, dutyLen, cycleLen, mode) } // Mode: Set pin Mode @@ -638,17 +639,20 @@ func SetFreq(pin Pin, freq int) { // The channels are: // channel 1 (pwm0) for pins 12, 18, 40 // channel 2 (pwm1) for pins 13, 19, 41, 45. +// +// NOTE without root permission this function will simply do nothing successfully func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) { - SetDutyCycleMsen(pin, dutyLen, cycleLen, 1) // Default PWM algorithm is Mark/Space, msen = 1 + SetDutyCycleWithPwmMode(pin, dutyLen, cycleLen, MarkSpace) } -// SetDutyCycleMsen extends SetDutyCycle to allow for the specification of the PWM -// algorithm to be used, Balanced or Mark/Space. 'msen' is used to indicate which -// PWM algorithm to use. The constants Balanced or Markspace should be used as the -// value. See 'SetDutyCycle(pin, dutyLen, cycleLen)' above for more information -// regarding how to use 'SetDutyCycleMsen()' -func SetDutyCycleMsen(pin Pin, dutyLen, cycleLen, msen uint32) { +// SetDutyCycleWithPwmMode extends SetDutyCycle to allow for the specification of the PWM +// algorithm to be used, Balanced or Mark/Space. The constants Balanced or MarkSpace +// as the value. See 'SetDutyCycle(pin, dutyLen, cycleLen)' above for more information +// regarding how to use 'SetDutyCycleWithPwmMode()'. +// +// NOTE without root permission this function will simply do nothing successfully +func SetDutyCycleWithPwmMode(pin Pin, dutyLen, cycleLen uint32, mode bool) { const pwmCtlReg = 0 var ( pwmDatReg uint @@ -673,17 +677,24 @@ func SetDutyCycleMsen(pin Pin, dutyLen, cycleLen, msen uint32) { const ctlMask = 255 // ctl setting has 8 bits for each channel const pwen = 1 << 0 // enable pwm - msen = msen << 7 + var msen uint32 = 0 + // The MSEN1 field in the CTL register is at offset 7. This block starts with the assumption + // that 'msen' will be associated with channel 'pwm0'. If this is not the case, 'msen' will + // be further shifted in the next code block below to the MSEN2 field at offset 15. + if mode == MarkSpace { + msen = 1 << 7 + } - // reset settings + // Shifting 'pwen' and 'msen' puts the associated values at the correct offset within the CTL + // register ('pwmCtlReg'). In addition, 'msen' is associated with a PWM channel depending on the + // value of 'pin' (see above). 'msen' will either stay at offset 7, as set above for channel 'pwm0', + // or be shifted 8 bits if the the associated 'pin' is on channel 'pwm1'. pwmMem[pwmCtlReg] = pwmMem[pwmCtlReg]&^(ctlMask<