go-packages/go-rpio
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This commit is contained in:
Drahoslav 2017-11-20 10:22:14 +01:00
parent b1c90c6087
commit a1c4bb376e
1 changed files with 27 additions and 20 deletions
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47
rpio.go
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@ -161,12 +161,12 @@ func (pin Pin) Toggle() {
TogglePin(pin)
}
// Set frequency of Clock pin
// Set frequency of Clock or Pwm pin (see doc of SetFreq)
func (pin Pin) Freq(freq int) {
SetFreq(pin, freq)
}
// Set duty cycle for pwm pin
// Set duty cycle for Pwm pin (see doc of SetDutyCycle)
func (pin Pin) DutyCycle(dutyLen, cycleLen uint32) {
SetDutyCycle(pin, dutyLen, cycleLen)
}
@ -329,14 +329,14 @@ func PullMode(pin Pin, pull Pull) {
// Set clock speed for given pin in Clock or Pwm mode
//
// freq should be in range 4688Hz - 19.2MHz to prevent unexpected behavior
// (for smaller frequencies use Pwm pin with large cycle range or implement custom software clock using output pin and sleep)
// Param freq should be in range 4688Hz - 19.2MHz to prevent unexpected behavior,
// hovewer output frequency of Pwm pins can be further adjusted with setDutyCycle.
// (Thus for smaller frequencies use Pwm pin with large cycle range or implement custom software clock using output pin and sleep.)
//
// Note that some pins share the same clock source, it means that
// changing frequency for one pin will change it also for all pins within a group
// The groups are: clk0 (4, 20, 32, 34), clk1 (5, 21, 42, 43) and clk2 (6 and 43)
// Also all pwm pins (12, 13, 18, 19, 40, 41, 45) share same source clock,
// but final output frequency of pwm chanel can be adjusted individually with setDutyCycle
// The groups are: clk0 (4, 20, 32, 34), clk1 (5, 21, 42, 43) and clk2 (6 and 43).
// Also all pwm pins (12, 13, 18, 19, 40, 41, 45) share same source clock.
func SetFreq(pin Pin, freq int) {
// TODO: would be nice to choose best clock source depending on target frequency, oscilator is used for now
const sourceFreq = 19200000 // oscilator frequency
@ -360,7 +360,7 @@ func SetFreq(pin Pin, freq int) {
case 6, 43: // clk2
clkCtlReg += 4
clkDivReg += 5
case 12, 13, 40, 41, 45, 18, 19: // pwm_clk - shared clk for both pwm chanels
case 12, 13, 40, 41, 45, 18, 19: // pwm_clk - shared clk for both pwm channels
clkCtlReg += 12
clkDivReg += 13
StopPwm() // pwm clk busy wont go down without stopping pwm first
@ -400,14 +400,21 @@ func SetFreq(pin Pin, freq int) {
// Set cycle length (range) and duty length (data) for pwm in M/S mode
//
// |<- duty ->|
// __________
// _/ \___________/
// |<------ cycle ------->|
// |<- duty ->|
// __________
// _/ \_____________/
// |<------- cycle -------->|
//
// Note that some pins share common pwm chanel,
// so calling this function will set same duty cycle for all pins belonig to chanel
// Its chanel pwm0 for pins 12, 18, 40, and pwm1 for pins 13, 19, 41, 45
// Output frequency is computed as pwm clock frequency divided by cycle length
// So, to set Pwm pin to freqency 38kHz with duty cycle 1/4 use this combination:
//
// pin.Pwm()
// pin.DutyCycle(1, 4)
// pin.Freq(38000*4)
//
// Note that some pins share common pwm channel,
// so calling this function will set same duty cycle for all pins belongig to channel.
// It is channel 1 (pwm0) for pins 12, 18, 40, and channel 2 (pwm1) for pins 13, 19, 41, 45.
func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) {
const pwmCtlReg = 0
var (
@ -417,11 +424,11 @@ func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) {
)
switch pin {
case 12, 18, 40: // chanel pwm0
case 12, 18, 40: // channel pwm0
pwmRngReg = 4
pwmDatReg = 5
shift = 0
case 13, 19, 41, 45: // chanel pwm1
case 13, 19, 41, 45: // channel pwm1
pwmRngReg = 8
pwmDatReg = 9
shift = 8
@ -429,7 +436,7 @@ func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) {
return
}
const ctlMask = 255 // ctl setting has 8 bits for each chanel
const ctlMask = 255 // ctl setting has 8 bits for each channel
const pwen = 1 << 0 // enable pwm
const msen = 1 << 7 // use M/S transition instead of pwm algorithm
@ -443,14 +450,14 @@ func SetDutyCycle(pin Pin, dutyLen, cycleLen uint32) {
// NOTE without root permission this changes will simply do nothing successfully
}
// Stop pwm for both chanels
// Stop pwm for both channels
func StopPwm() {
const pwmCtlReg = 0
const pwen = 1
pwmMem[pwmCtlReg] = pwmMem[pwmCtlReg] &^ (pwen<<8 | pwen)
}
// Start pwm for both chanels
// Start pwm for both channels
func StartPwm() {
const pwmCtlReg = 0
const pwen = 1