upload page added + parchment properly waits for ack command

device.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"fmt"
 	"time"
 
@@ -15,6 +16,8 @@ type Device struct {
 	Connected bool
 }
 
+var commandAck = []byte{0xAA, 0x06, 0x00, 0x00, 0x00}
+
 // NewDevice creates a new Device instance.
 func NewDevice() *Device {
 	return &Device{}
@@ -51,18 +54,16 @@ func (d *Device) Connect() error {
 
 	d.Port = port
 	d.Connected = true
+	_ = d.Port.SetReadTimeout(100 * time.Millisecond)
 
 	// Send dev mode request
 	// 0xAA 0x04 0x00 0x00 0x00 is the command sequence for dev mode
-	_, err = d.Port.Write([]byte{0xAA, 0x04, 0x00, 0x00, 0x00})
+	err = d.sendCommand([]byte{0xAA, 0x04, 0x00, 0x00, 0x00})
 	if err != nil {
 		d.Close()
-		return fmt.Errorf("failed to send dev mode request: %w", err)
+		return fmt.Errorf("failed to enter dev mode: %w", err)
 	}
 
-	// Allow some time for the device to respond or settle if needed
-	time.Sleep(100 * time.Millisecond)
-
 	return nil
 }
 
@@ -73,14 +74,10 @@ func (d *Device) ExitDevMode() error {
 	}
 
 	// disable dev mode
-	_, err := d.Port.Write([]byte{0xAA, 0x05, 0x00, 0x00, 0x00})
-	if err != nil {
-		return fmt.Errorf("failed to send exit dev mode command: %w", err)
+	if err := d.sendCommand([]byte{0xAA, 0x05, 0x00, 0x00, 0x00}); err != nil {
+		return fmt.Errorf("failed to exit dev mode: %w", err)
 	}
 
-	// Allow some time for the device to respond or settle if needed
-	time.Sleep(100 * time.Millisecond)
-
 	return nil
 }
 
@@ -108,3 +105,57 @@ func (d *Device) Write(data []byte) (int, error) {
 	}
 	return d.Port.Write(data)
 }
+
+func (d *Device) sendCommand(cmd []byte) error {
+	if d.Port == nil {
+		return fmt.Errorf("port not open")
+	}
+	if _, err := d.Port.Write(cmd); err != nil {
+		return fmt.Errorf("failed to send command: %w", err)
+	}
+	if err := d.waitForResponse(commandAck, 2*time.Second); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (d *Device) waitForResponse(expected []byte, timeout time.Duration) error {
+	if d.Port == nil {
+		return fmt.Errorf("port not open")
+	}
+	if len(expected) == 0 {
+		return fmt.Errorf("expected response is empty")
+	}
+
+	deadline := time.NewTimer(timeout)
+	defer deadline.Stop()
+
+	readBuf := make([]byte, 64)
+	window := make([]byte, 0, len(expected)*4)
+	maxWindow := len(expected) * 4
+	if maxWindow < 64 {
+		maxWindow = 64
+	}
+
+	for {
+		select {
+		case <-deadline.C:
+			return fmt.Errorf("timeout waiting for response %x", expected)
+		default:
+			n, err := d.Port.Read(readBuf)
+			if err != nil {
+				return fmt.Errorf("failed while waiting for response: %w", err)
+			}
+			if n == 0 {
+				continue
+			}
+			window = append(window, readBuf[:n]...)
+			if len(window) > maxWindow {
+				window = window[len(window)-maxWindow:]
+			}
+			if bytes.Contains(window, expected) {
+				return nil
+			}
+		}
+	}
+}