mirror of
https://github.com/tinygo-org/drivers.git
synced 2026-07-26 10:38:41 +00:00
Martin Heck
70 lines
2.0 KiB
Go
70 lines
2.0 KiB
Go
//go:build tinygo && (rp2040 || rp2350 || stm32 || k210 || esp32c3 || nrf || sam || (avr && (atmega328p || atmega328pb)))
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// Implementation based on:
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// https://gist.github.com/aykevl/3fc1683ed77bb0a9c07559dfe857304a
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// Note: build constraints in this file list targets that define machine.PinToggle.
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// If this is supported for additional targets in the future, they can be added above.
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package encoders
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import (
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"machine"
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"runtime/volatile"
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)
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var (
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states = []int8{0, -1, 1, 0, 1, 0, 0, -1, -1, 0, 0, 1, 0, 1, -1, 0}
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)
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// NewQuadratureViaInterrupt returns a rotary encoder device that uses GPIO
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// interrupts and a lookup table to keep track of quadrature state changes.
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//
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// This constructur is only available for TinyGo targets for which machine.PinToggle
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// is defined as a valid interrupt type.
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func NewQuadratureViaInterrupt(pinA, pinB machine.Pin) *QuadratureDevice {
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return &QuadratureDevice{impl: &quadInterruptImpl{pinA: pinA, pinB: pinB, oldAB: 0b00000011}}
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}
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type quadInterruptImpl struct {
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pinA machine.Pin
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pinB machine.Pin
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// precision int
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oldAB int
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value volatile.Register32
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}
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func (enc *quadInterruptImpl) configure(cfg QuadratureConfig) error {
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enc.pinA.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
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enc.pinA.SetInterrupt(machine.PinToggle, enc.interrupt)
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enc.pinB.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
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enc.pinB.SetInterrupt(machine.PinToggle, enc.interrupt)
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return nil
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}
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func (enc *quadInterruptImpl) interrupt(pin machine.Pin) {
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aHigh, bHigh := enc.pinA.Get(), enc.pinB.Get()
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enc.oldAB <<= 2
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if aHigh {
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enc.oldAB |= 1 << 1
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}
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if bHigh {
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enc.oldAB |= 1
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}
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enc.writeValue(enc.readValue() + int(states[enc.oldAB&0x0f]))
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}
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// readValue gets the value using volatile operations and returns it as an int
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func (enc *quadInterruptImpl) readValue() int {
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return int(enc.value.Get())
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}
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// writeValue set the value to the specified int using volatile operations
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func (enc *quadInterruptImpl) writeValue(v int) {
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enc.value.Set(uint32(v))
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}
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