Documentation
¶
Overview ¶
Package static provides the implementation of a static software-based NFC Forum Type 4 Tag which holds a NDEF Message.
See https://gitlab.com/snippets/18718 for an example on how to use it together with the `swtag` driver.
Index ¶
Examples ¶
Constants ¶
const ( NFCForumMajorVersion = 2 NFCForumMinorVersion = 0 )
Version of the specification implemented by this tag
const NDEFAPPLICATION = uint64(0xD2760000850101)
NDEFAPPLICATION is the name for the NDEF Application.
const NDEFFileAddress = uint16(0x8888)
NDEFFileAddress Address in which the NDEF File is stored. It is initialized to a default of 0x8888.
The valid ranges are 0x0001-E101,0xE104-3EFF, 0x4000-FFFE. Values 0x0000, 0xE102, 0xE103, 0x3F00, 0x3FFF are reserved. 0xFFFF is RFU.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Tag ¶
type Tag struct {
// contains filtered or unexported fields
}
Tag implements a static NFC Type 4 Tags which holds a NDEFMessage.
It called static because the message that is returned is always the same regardless of how many times it is Read.
Since the static Tag implements the `tags.Tag` interface, this tag can be used with the `nfctype4/drivers/swtag`. Please check the `swtag` module documentation for more information on the different uses.
Please use static.New() to create tags, or remember to do a Tag.Initialize() as otherwise tags will refuse to work.
Example (Read) ¶
// Let's create a NDEF Message first
payload := generic.Payload{
Payload: []byte("\x01test.payload"),
}
ndefMessage := ndef.NewMessage(
ndef.NFCForumWellKnownType, "U", "",
&payload)
// Store this message in a static tag
tag := New()
err := tag.SetMessage(ndefMessage)
if err != nil {
fmt.Println(err)
}
// To read our tag we need a nfctype4.Device configured
// with the swtag driver. The driver is connected to
// our Tag.
driver := &swtag.Driver{
Tag: tag,
}
device := nfctype4.New(driver)
// Now we can read the message using the NFC Type 4 Tag
// operation specification
receivedMessage, err := device.Read()
if err != nil {
fmt.Println(err)
} else {
fmt.Println(receivedMessage)
}
Output: urn:nfc:wkt:U:http://www.test.payload
Example (Write) ¶
// Store this message in a static tag
tag := New()
// To read/write our tag we need a nfctype4.Device configured
// with the swtag driver. The driver is connected to
// our Tag.
driver := &swtag.Driver{
Tag: tag,
}
device := nfctype4.New(driver)
// Now we can update the message using the NFC Type 4 Tag
// operation specification with a new message
ndefMessage := ndef.NewTextMessage("This is a new message", "en")
err := device.Update(ndefMessage)
if err != nil {
fmt.Println(err)
return
}
// Finally let's peek at the message stored in the tag
tagMessage := tag.GetMessage()
fmt.Println(tagMessage)
Output: urn:nfc:wkt:T:This is a new message
func (*Tag) Command ¶
Command lets the Software tag receive Commands (CAPDUs) and provide respones (RAPDUs) according to each command. It is the heart of the behaviour of a NFC Type 4 Tag.
func (*Tag) GetMessage ¶
func (tag *Tag) GetMessage() *ndef.Message
GetMessage allows to retrieve the NDEF message stored in the tag. It returns nil when there is nothing stored.
func (*Tag) Initialize ¶
func (tag *Tag) Initialize()
Initialize resets a Tag to an initialized state (empty) It will drop the memory contents if they previously existed and de-select any files.
func (*Tag) SetMessage ¶
SetMessage programs the NDEF message for this tag. It returns an error if the m.Marshal() does (which would indicate and invalid message).
Notes ¶
Bugs ¶
Tag is not super-strict with the error responses in case of unexpected Commands.
Source Files