mirror of
https://github.com/kidoman/embd
synced 2024-12-21 12:20:05 +01:00
gpio: provide an api to allow performance timing of pulses
the us020 driver is the first consumer of this functionality
This commit is contained in:
parent
af23a999ba
commit
5b852d9f42
@ -10,6 +10,7 @@ import (
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"os"
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"path"
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"strconv"
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"time"
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)
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type digitalPin struct {
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@ -19,11 +20,13 @@ type digitalPin struct {
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val *os.File
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activeLow *os.File
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readBuf []byte
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initialized bool
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}
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func newDigitalPin(n int) DigitalPin {
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return &digitalPin{n: n}
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return &digitalPin{n: n, readBuf: make([]byte, 1)}
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}
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func (p *digitalPin) N() int {
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@ -107,21 +110,36 @@ func (p *digitalPin) SetDirection(dir Direction) error {
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return err
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}
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func (p *digitalPin) read() (int, error) {
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if _, err := p.val.ReadAt(p.readBuf, 0); err != nil {
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return 0, err
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}
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if p.readBuf[0] == 49 {
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return 1, nil
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}
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return 0, nil
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}
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func (p *digitalPin) Read() (int, error) {
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if err := p.init(); err != nil {
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return 0, err
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}
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buf := make([]byte, 1)
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if _, err := p.val.Read(buf); err != nil {
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return 0, err
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return p.read()
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}
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var (
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lowBytes = []byte{48}
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highBytes = []byte{49}
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)
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func (p *digitalPin) write(val int) error {
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bytes := lowBytes
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if val == High {
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bytes = highBytes
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}
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p.val.Seek(0, 0)
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var val int
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if buf[0] == '1' {
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val = 1
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}
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return val, nil
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_, err := p.val.Write(bytes)
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return err
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}
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func (p *digitalPin) Write(val int) error {
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@ -129,12 +147,58 @@ func (p *digitalPin) Write(val int) error {
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return err
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}
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str := "0"
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if val == High {
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str = "1"
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return p.write(val)
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}
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func (p *digitalPin) TimePulse(state int) (time.Duration, error) {
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if err := p.init(); err != nil {
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return 0, err
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}
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_, err := p.val.WriteString(str)
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return err
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aroundState := Low
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if state == Low {
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aroundState = High
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}
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// Wait for any previous pulse to end
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for {
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v, err := p.read()
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if err != nil {
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return 0, err
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}
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if v == aroundState {
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break
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}
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}
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// Wait until ECHO goes high
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for {
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v, err := p.read()
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if err != nil {
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return 0, err
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}
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if v == state {
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break
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}
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}
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startTime := time.Now() // Record time when ECHO goes high
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// Wait until ECHO goes low
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for {
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v, err := p.read()
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if err != nil {
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return 0, err
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}
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if v == aroundState {
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break
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}
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}
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return time.Since(startTime), nil // Calculate time lapsed for ECHO to transition from high to low
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}
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func (p *digitalPin) ActiveLow(b bool) error {
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5
gpio.go
5
gpio.go
@ -2,6 +2,8 @@
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package embd
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import "time"
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// The Direction type indicates the direction of a GPIO pin.
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type Direction int
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@ -32,6 +34,9 @@ type DigitalPin interface {
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// Read reads the value from the pin.
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Read() (int, error)
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// TimePulse measures the duration of a pulse on the pin.
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TimePulse(state int) (time.Duration, error)
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// SetDirection sets the direction of the pin (in/out).
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SetDirection(dir Direction) error
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@ -91,36 +91,11 @@ func (d *US020) Distance() (float64, error) {
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glog.V(2).Infof("us020: waiting for echo to go high")
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// Wait until ECHO goes high
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for {
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v, err := d.EchoPin.Read()
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if err != nil {
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return 0, err
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}
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if v == embd.High {
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break
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}
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duration, err := d.EchoPin.TimePulse(embd.High)
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if err != nil {
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return 0, err
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}
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startTime := time.Now() // Record time when ECHO goes high
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glog.V(2).Infof("us020: waiting for echo to go low")
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// Wait until ECHO goes low
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for {
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v, err := d.EchoPin.Read()
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if err != nil {
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return 0, err
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}
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if v == embd.Low {
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break
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}
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}
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duration := time.Since(startTime) // Calculate time lapsed for ECHO to transition from high to low
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// Calculate the distance based on the time computed
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distance := float64(duration.Nanoseconds()) / 10000000 * (d.speedSound / 2)
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