Added driver to decode signal from Silvan *1527 chips.

otp1527/otp1527.go

@@ -0,0 +1,128 @@
+// Package otp1527 implements a driver to decode signal transmitted over 433MHz
+// by various key fob, leak detectors, etc., which are based on Silvan OTP
+// Encoder chips HS1527, EV1527, RT1527, or FP1527.
+// See http://sc-tech.cn/en/hs1527.pdf for details.
+// This package works with microcontrollers that support GPIO PinToggle interrupt.
+//
+// Example:
+//
+//  package main
+//
+//  import (
+// 	 "fmt"
+// 	 "machine"
+//
+// 	 "tinygo.org/x/drivers/otp1527"
+//  )
+//
+//  func main() {
+// 	 d := otp1527.NewDecoder(machine.Pin(3), 24, 0)
+// 	 for {
+// 		select {
+// 		case v := <-d.Out():
+// 			println("RECV:", fmt.Sprintf("0x%02x", v))
+// 		}
+// 	 }
+//  }
+//
+
+package otp1527
+
+import "machine"
+
+type OTP1527 struct {
+	pin         machine.Pin
+	ch          chan uint32
+	time        int64
+	preambleClk int64
+	timeHigh    int64
+	data        uint32
+	bits        int
+	last        bool
+}
+
+// NewDecoder create driver to decode stream generated by HS1527 compatible source
+// and deliver decoded data into output buffered channel of channelSize size.
+// When channelSize set to -1, the size default to 100.
+func NewDecoder(p machine.Pin, channelSize int) *OTP1527 {
+	if channelSize < 0 {
+		channelSize = 100
+	}
+	d := OTP1527{pin: p, ch: make(chan uint32, channelSize)}
+	d.pin.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
+	if err := d.pin.SetInterrupt(machine.PinToggle, func(p machine.Pin) {
+		d.interrupt()
+	}); err != nil {
+		println("error:", err.Error())
+	}
+	return &d
+}
+
+// Out return output channel for decoded data.
+func (d *OTP1527) Out() <-chan uint32 {
+	return d.ch
+}
+
+func (d *OTP1527) interrupt() {
+	now := machine.GetNano()
+	// filter signal
+	highCnt := 0
+	for n := 0; n < 65; n++ {
+		v := d.pin.Get()
+		if v {
+			highCnt++
+		} else {
+			highCnt--
+		}
+	}
+	pin := highCnt > 0
+	// decode
+	if d.last != pin {
+		interval := now - d.time
+		if pin == true {
+			d.timeHigh = interval
+		} else {
+			if d.timeHigh > 0 {
+				switch {
+				case interval/d.timeHigh > 20:
+					// this is end of preamble
+					d.preambleClk = interval / 31
+					d.resetData()
+
+				case (interval+d.timeHigh) < d.preambleClk*5 && interval/d.timeHigh > 0:
+					// this is 0
+					d.data = d.data << 1
+					d.bits++
+					// check for last data
+					if d.bits == 24 {
+						d.ch <- d.data
+						d.resetData()
+					}
+
+				case (interval+d.timeHigh) < d.preambleClk*5 && interval/d.timeHigh == 0:
+					// this is 1
+					d.data = d.data<<1 | 1
+					d.bits++
+					// check for last data
+					if d.bits == 24 {
+						d.ch <- d.data
+						d.resetData()
+					}
+
+				default:
+					d.resetData()
+				}
+			} else {
+				d.resetData()
+			}
+		}
+		d.time = now
+		d.last = pin
+	}
+}
+
+//go:inline
+func (d *OTP1527) resetData() {
+	d.data = 0
+	d.bits = 0
+}