SDWire Go Library

Go library for controlling SDWireC & SDWire3 devices - USB-controlled SD card multiplexers for automated testing and development.

Features

🔀 SD Card Switching - Switch SD cards between target device and host computer
🔍 Device Discovery - Automatically find and enumerate connected devices
💾 Device Information - Access device serial, product, and manufacturer details

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

Function	Description
New() (*SDWireC, error)	Connect to the first available device
NewWithSerial(serial string) (*SDWireC, error)	Connect to device by serial number
ListDevices() ([]*DeviceInfo, error)	List all connected devices
Close() error	Close device connection

Device Control

Function	Description
SetMode(mode SwitchMode) error	Switch to specified mode

Device Information

Function	Description
GetSerial() string	Get device serial number
GetProduct() string	Get device product name
GetManufacturer() string	Get device manufacturer

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. Check VID/PID - SDWireC should appear as 04E8:6001 when listing USB devices
3. Verify permissions - Ensure you have proper USB device access permissions

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

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