go-packages/go-rpio
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add support for PWM balanced mode

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This commit is contained in:
youngkin 2021-11-03 17:44:36 +00:00
parent 2ab4c0432c
commit 02c0360e26
1 changed files with 44 additions and 20 deletions
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30
rpio.go
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@ -146,6 +146,12 @@ const (
High High
) )
// Which PWM algorithm to use, Balanced or Mark/Space
const (
Balanced = iota
MarkSpace
)
// Pull Up / Down / Off // Pull Up / Down / Off
const ( const (
PullOff Pull = iota PullOff Pull = iota
@ -222,6 +228,11 @@ func (pin Pin) DutyCycle(dutyLen, cycleLen uint32) {
SetDutyCycle(pin, dutyLen, cycleLen) 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)
}
// Mode: Set pin Mode // Mode: Set pin Mode
func (pin Pin) Mode(mode Mode) { func (pin Pin) Mode(mode Mode) {
PinMode(pin, mode) PinMode(pin, mode)
@ -497,14 +508,14 @@ func PullMode(pin Pin, pull Pull) {
case PullUp: case PullUp:
p = 1 p = 1
case PullDown: case PullDown:
p = 2; p = 2
} }
// This is verbatim C code from raspi-gpio.c // This is verbatim C code from raspi-gpio.c
pullbits := gpioMem[pullreg] pullbits := gpioMem[pullreg]
pullbits &= ^(3 << pullshift) pullbits &= ^(3 << pullshift)
pullbits |= (p << pullshift) pullbits |= (p << pullshift)
gpioMem[pullreg]= pullbits gpioMem[pullreg] = pullbits
} else { } else {
// Pull up/down/off register has offset 38 / 39, pull is 37 // Pull up/down/off register has offset 38 / 39, pull is 37
pullClkReg := pin/32 + 38 pullClkReg := pin/32 + 38
@ -628,11 +639,22 @@ func SetFreq(pin Pin, freq int) {
// channel 1 (pwm0) for pins 12, 18, 40 // channel 1 (pwm0) for pins 12, 18, 40
// channel 2 (pwm1) for pins 13, 19, 41, 45. // channel 2 (pwm1) for pins 13, 19, 41, 45.
func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) { func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) {
SetDutyCycleMsen(pin, dutyLen, cycleLen, 1) // Default PWM algorithm is Mark/Space, msen = 1
}
// 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) {
const pwmCtlReg = 0 const pwmCtlReg = 0
var ( var (
pwmDatReg uint pwmDatReg uint
pwmRngReg uint pwmRngReg uint
shift uint // offset inside ctlReg shift uint // offset inside ctlReg
) )
switch pin { switch pin {
@ -646,11 +668,12 @@ func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) {
shift = 8 shift = 8
default: default:
return return
} }
const ctlMask = 255 // ctl setting has 8 bits for each channel const ctlMask = 255 // ctl setting has 8 bits for each channel
const pwen = 1 << 0 // enable pwm const pwen = 1 << 0 // enable pwm
const msen = 1 << 7 // use M/S transition instead of pwm algorithm msen = msen << 7
// reset settings // reset settings
pwmMem[pwmCtlReg] = pwmMem[pwmCtlReg]&^(ctlMask<<shift) | msen<<shift | pwen<<shift pwmMem[pwmCtlReg] = pwmMem[pwmCtlReg]&^(ctlMask<<shift) | msen<<shift | pwen<<shift
@ -660,6 +683,7 @@ func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) {
time.Sleep(time.Microsecond * 10) time.Sleep(time.Microsecond * 10)
// NOTE without root permission this changes will simply do nothing successfully // NOTE without root permission this changes will simply do nothing successfully
} }
// StopPwm: Stop pwm for both channels // StopPwm: Stop pwm for both channels