Add Go UART tool to query firmware VERSION over serial.

Framed protobuf client for /dev/ttyUSB0 at 921600 baud with generated uart_messages types matching the device protocol. Co-authored-by: Cursor <cursoragent@cursor.com>
2026-05-18 22:06:58 +02:00
parent a1629fb3db
commit bde4c473ef
6 changed files with 1308 additions and 0 deletions
@@ -0,0 +1,126 @@
+package uart
+
+import (
+	"errors"
+	"fmt"
+	"io"
+)
+
+const (
+	StartMarker = 0xAA
+	StopMarker  = 0xCC
+	MaxPayload  = 252
+)
+
+var (
+	ErrInvalidFrame = errors.New("invalid uart frame")
+	ErrTimeout      = errors.New("read timeout")
+)
+
+// EncodeFrame builds a framed packet: 0xAA len payload xor(payload) 0xCC.
+func EncodeFrame(payload []byte) ([]byte, error) {
+	if len(payload) == 0 || len(payload) > MaxPayload {
+		return nil, fmt.Errorf("payload length %d out of range 1..%d", len(payload), MaxPayload)
+	}
+
+	frame := make([]byte, 0, 4+len(payload))
+	frame = append(frame, StartMarker, byte(len(payload)))
+	var checksum byte
+	for _, b := range payload {
+		frame = append(frame, b)
+		checksum ^= b
+	}
+	frame = append(frame, checksum, StopMarker)
+	return frame, nil
+}
+
+type Parser struct {
+	state    int
+	len      int
+	payload  []byte
+	index    int
+	checksum byte
+}
+
+const (
+	stateStart = iota
+	stateLen
+	stateData
+	stateChecksum
+	stateStop
+)
+
+func NewParser() *Parser {
+	return &Parser{state: stateStart}
+}
+
+// Feed ingests one byte. ok is true when a complete frame is ready.
+func (p *Parser) Feed(b byte) (payload []byte, ok bool, err error) {
+	switch p.state {
+	case stateStart:
+		if b == StartMarker {
+			p.index = 0
+			p.checksum = 0
+			p.state = stateLen
+		}
+	case stateLen:
+		if b == 0 || b > MaxPayload {
+			p.state = stateStart
+		} else {
+			p.len = int(b)
+			p.payload = make([]byte, p.len)
+			p.state = stateData
+		}
+	case stateData:
+		p.payload[p.index] = b
+		p.checksum ^= b
+		p.index++
+		if p.index >= p.len {
+			p.state = stateChecksum
+		}
+	case stateChecksum:
+		if b == p.checksum {
+			p.state = stateStop
+		} else {
+			p.state = stateStart
+			return nil, false, ErrInvalidFrame
+		}
+	case stateStop:
+		p.state = stateStart
+		if b == StopMarker {
+			out := make([]byte, len(p.payload))
+			copy(out, p.payload)
+			return out, true, nil
+		}
+	}
+	return nil, false, nil
+}
+
+// ReadFrame reads bytes from r until one full frame is parsed or an error occurs.
+func ReadFrame(r io.Reader, buf []byte) ([]byte, error) {
+	if buf == nil {
+		buf = make([]byte, 256)
+	}
+	parser := NewParser()
+
+	for {
+		n, err := r.Read(buf)
+		if n > 0 {
+			for i := 0; i < n; i++ {
+				payload, ok, perr := parser.Feed(buf[i])
+				if perr != nil {
+					return nil, perr
+				}
+				if ok {
+					return payload, nil
+				}
+			}
+		}
+		if err != nil {
+			if err == io.EOF {
+				return nil, ErrInvalidFrame
+			}
+			return nil, err
+		}
+	}
+}