sdwire

SDWire Go Library

Go library for controlling SDWireC devices - USB-controlled SD card multiplexers for automated testing and development.

Features

🔀 SD Card Switching - Switch SD cards between target device and host computer
🎯 Simple API - Easy-to-use interface following Go best practices
🔍 Device Discovery - Automatically find and enumerate connected devices
💾 Device Information - Access device serial, product, and manufacturer details
🖥️ Cross-Platform - Works on Linux, macOS, and Windows
⚡ No Dependencies - Only uses standard library and gousb

Installation

go get github.com/fcjr/sdwire

Quick Start

package main

import (
    "log"
    "github.com/fcjr/sdwire"
)

func main() {
    // Connect to the first available SDWireC device
    device, err := sdwire.New()
    if err != nil {
        log.Fatal(err)
    }
    defer device.Close()

    // Switch SD card to host computer for flashing
    device.SetMode(sdwire.ModeHost)
    
    // Flash your image here...
    
    // Switch SD card to target device for testing
    device.SetMode(sdwire.ModeTarget)
}

Usage Examples

Basic SD Card Switching

device, err := sdwire.New()
if err != nil {
    log.Fatal(err)
}
defer device.Close()

// Switch to Host (for flashing/accessing SD card)
err = device.SetMode(sdwire.ModeHost)
if err != nil {
    log.Fatal(err)
}

// Switch to Target (for testing)
err = device.SetMode(sdwire.ModeTarget)
if err != nil {
    log.Fatal(err)
}

Getting Device Information

import (
    "fmt"
    "log"
    "github.com/fcjr/sdwire"
)

device, err := sdwire.New()
if err != nil {
    log.Fatal(err)
}
defer device.Close()

// Get device information
fmt.Printf("Device: %s [%s::%s]\n", 
    device.GetSerial(), 
    device.GetProduct(), 
    device.GetManufacturer())

Managing Multiple Devices

import (
    "fmt"
    "log"
    "github.com/fcjr/sdwire"
)

// List all connected SDWireC devices
devices, err := sdwire.ListDevices()
if err != nil {
    log.Fatal(err)
}

for i, info := range devices {
    fmt.Printf("Device %d: %s [%s::%s]\n", 
        i+1, info.Serial, info.Product, info.Manufacturer)
}

// Connect to a specific device by serial number
device, err := sdwire.NewWithSerial(devices[0].Serial)
if err != nil {
    log.Fatal(err)
}
defer device.Close()

API Reference

Types

type SDWireC struct {
    // Represents a connected SDWireC device
}

type SwitchMode int
const (
    ModeTarget SwitchMode = iota  // Target device mode
    ModeHost                      // Host computer mode
)

type DeviceInfo struct {
    Serial       string
    Product      string
    Manufacturer string
}

Connection Management

Device Control

Device Information

Constants

const (
    ModeTarget  // Connects SD card to target device
    ModeHost    // Connects SD card to host computer
)

Hardware Requirements

• SDWireC device (USB-controlled SD card multiplexer)
• USB connection to host computer
• Proper USB permissions (see Troubleshooting)

Supported Operating Systems

• Linux ✅ (Tested on Ubuntu, Debian)
• macOS ✅ (Tested on macOS 10.15+)
• Windows ✅ (Tested on Windows 10+)

Troubleshooting

Device Not Found

If ListDevices() returns no devices:

1. Check USB connection - Ensure the SDWireC is properly connected
2. Verify device - Run the debug utility to list all USB devices:

   go run debug/list_usb.go
   

3. Check VID/PID - SDWireC should appear as 04E8:6001

Permission Issues (Linux)

If you get permission errors on Linux:

1. Add udev rules - Create /etc/udev/rules.d/99-sdwire.rules:

   SUBSYSTEM=="usb", ATTR{idVendor}=="04e8", ATTR{idProduct}=="6001", MODE="0666"
   

2. Reload udev rules:

   sudo udevadm control --reload-rules
   sudo udevadm trigger
   

3. Add user to plugdev group:

   sudo usermod -a -G plugdev $USER
   

Multiple Devices

When using multiple SDWireC devices:

devices, err := sdwire.ListDevices()
if err != nil {
    log.Fatal(err)
}

for _, info := range devices {
    device, err := sdwire.NewWithSerial(info.Serial)
    if err != nil {
        continue
    }
    defer device.Close()
    
    // Use device...
    device.SetMode(sdwire.ModeTarget)
}

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

License

MIT License - see LICENSE file for details.

Related Projects

• sdwire-cli - Python CLI tool for SDWireC
• ykush3 - Go library for YKUSH3 USB switches

Made with ❤️ for embedded testing automation