parchment/device.go

package main

import (
	"fmt"
	"time"

	"go.bug.st/serial"
	"go.bug.st/serial/enumerator"
)

// Device manages the serial connection to the Cardputer.
type Device struct {
	PortName  string
	Port      serial.Port
	Connected bool
}

// NewDevice creates a new Device instance.
func NewDevice() *Device {
	return &Device{}
}

// FindCardputer searches for a connected Cardputer by VID.
func (d *Device) FindCardputer() (string, error) {
	ports, err := enumerator.GetDetailedPortsList()
	if err != nil {
		return "", err
	}
	for _, port := range ports {
		if port.VID == "303a" { // Cardputer VID
			d.PortName = port.Name
			return port.Name, nil
		}
	}
	return "", fmt.Errorf("Cardputer not found")
}

// Connect opens the serial port and requests dev mode.
func (d *Device) Connect() error {
	if d.PortName == "" {
		return fmt.Errorf("no port name set")
	}

	mode := &serial.Mode{
		BaudRate: 115200,
	}
	port, err := serial.Open(d.PortName, mode)
	if err != nil {
		return fmt.Errorf("failed to open port: %w", err)
	}

	d.Port = port
	d.Connected = true

	// 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})
	if err != nil {
		d.Close()
		return fmt.Errorf("failed to send dev mode request: %w", err)
	}

	// Allow some time for the device to respond or settle if needed
	time.Sleep(100 * time.Millisecond)

	return nil
}

// ExitDevMode sends the command to exit dev mode.
func (d *Device) ExitDevMode() error {
	if !d.Connected || d.Port == nil {
		return fmt.Errorf("device not connected")
	}

	// Send exit dev mode command
	// TODO: Replace with the actual command sequence to exit dev mode
	// This is currently not implemented on the Cardputer side.

	return nil
}

// Close closes the serial port.
func (d *Device) Close() error {
	if d.Port != nil {
		// Try to exit dev mode before closing
		_ = d.ExitDevMode()

		// Allow some time for the command to be processed
		time.Sleep(100 * time.Millisecond)

		err := d.Port.Close()
		d.Port = nil
		d.Connected = false
		return err
	}
	return nil
}

// Write sends data to the device.
func (d *Device) Write(data []byte) (int, error) {
	if !d.Connected || d.Port == nil {
		return 0, fmt.Errorf("device not connected")
	}
	return d.Port.Write(data)
}