acr122u

This is a Go package for the ACR122U USB NFC Reader

Requirements

• https://www.acs.com.hk/en/products/3/acr122u-usb-nfc-reader/ - ACR122U USB NFC Reader
• https://pcsclite.apdu.fr/ - Middleware to access a smart card using SCard API (PC/SC)
• https://github.com/ebfe/scard - Go bindings to the PC/SC API

Under macOS pcsc-lite can be installed using homebrew: brew install pcsc-lite

Installation

go get -u github.com/peterhellberg/acr122u

Usage

Minimal example

package main

import (
	"fmt"

	"github.com/peterhellberg/acr122u"
)

func main() {
	ctx, err := acr122u.EstablishContext()
	if err != nil {
		panic(err)
	}

	ctx.ServeFunc(func(c acr122u.Card) {
		fmt.Printf("%x\n", c.UID())
	})
}

Using a struct that implements the acr122u.Handler interface

package main

import (
	"log"
	"os"

	"github.com/peterhellberg/acr122u"
)

func main() {
	ctx, err := acr122u.EstablishContext()
	if err != nil {
		panic(err)
	}

	h := &handler{log.New(os.Stdout, "", 0)}

	ctx.Serve(h)
}

type handler struct {
	acr122u.Logger
}

func (h *handler) ServeCard(c acr122u.Card) {
	h.Printf("%x\n", c.UID())
}

NATS

NATS is my favorite messaging system, so let’s see how we can use it with this package:

Publish each UID to a NATS subject

package main

import (
	nats "github.com/nats-io/go-nats"
	acr122u "github.com/peterhellberg/acr122u"
)

func main() {
	nc, err := nats.Connect(nats.DefaultURL)
	if err != nil {
		panic(err)
	}

	ctx, err := acr122u.EstablishContext()
	if err != nil {
		panic(err)
	}

	ctx.ServeFunc(func(c acr122u.Card) {
		nc.Publish("acr122u", c.UID())
	})
}

Subscribe to the NATS subject

package main

import (
	"fmt"
	"runtime"

	nats "github.com/nats-io/go-nats"
)

func main() {
	nc, err := nats.Connect(nats.DefaultURL)
	if err != nil {
		panic(err)
	}

	nc.Subscribe("acr122u", func(m *nats.Msg) {
		fmt.Printf("Received UID: %x\n", m.Data)
	})

	runtime.Goexit()
}

License (MIT)

Copyright (c) 2018-2019 Peter Hellberg

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.