HID Firmware

The HID firmware acts as a USB HID Keyboard and a Vendor-Specific HID device. The device scans for new tags and types the UID (or UID+SAK or the specified block) of a found tag by using virtual keystrokes.

Device modes

RFID device can be in two modes: scanning and application controlled mode. The default mode (i.e. then device mode after POR) is selected via the device settings. Factory defaults set it to scanning mode.

• When in scanning mode the device scans for new tags and types the UID (UID+SAk / block) of a found tag by using virtual keystrokes. One can control how the data is printed via the device settings (upper case / lower case, carriage return, etc). The tag presence is queried once every N ms. Factory default is 1000ms. Custom HID commands (except the one switching the mode and controlling the device settings) are ignored in the scanning mode.
• When the device in the application controlled mode, the user controlls the device behavior via custom HID commands.

HID Reports

This firmware has two reports

• Report 1 is used to send keyboard events when the device is in scanning mode and follows the standard HID Keyboard Report format
• Report 2 is used to configure the device, switching scan modes and query/read/write tags. Both IN- and OUT reports with ID 2 always consist of 63 bytes (64 including the report ID).

Custom HID commands

Custom HID commands are sent and received via HID report with ID 2. The report always consists of 63 bytes. The report ID is prepended to the data, therefore the full report length is 64 bytes. The first byte (after the ID one) is the command ID. Valid commands are listed below. The next bytes are command parameters. If the command parameters occupy less than 62 bytes, the remaining unused bytes are a padding and can have any arbitrary values that have no meaning.

The device answers with a report, where the first byte (after the report ID) is the command id (the same as the request), the next 4 bytes are the error code (32bit unsigned integer, little endian), and the following bytes are command specific. If the command parameters occupy less than 62 bytes, the remaining unused bytes are padding and can have any arbitrary values. If the error code is not zero, the following command-specific bytes cannot be trusted and must be regarded as meaningless.

The error code has the following bit fields:

• 0x00000001 - Protocol error
• 0x00000002 - Parity error
• 0x00000004 - Checksum error
• 0x00000008 - Collision
• 0x00000010 - Buffer overflow
• 0x00000020 - Tear event
• 0x00000040 - IC overheated
• 0x00000080 - FIFO write error
• 0x00000100 - Operation timed out
• 0x00000200 - Mifare NAK
• 0x00000400 - Authentication failure
• 0x00000800 - Generic communication error

The error code of 0 is OK (i.e. no error). ATTENTION: the data following the error code bytes is valid only if the error code is 0.

Command list:

• 0x01 - Device Information
• 0x02 - LED Control
• 0x03 - Buzzer Control
• 0x10 - Inventory Scan (all tags)
• 0x11 - Inventory Scan (the first tag)
• 0x12 - Inventory Scan (select the next tag)
• 0x13 - Check Tag Presence
• 0x20 - Select Tag
• 0x21 - Tag Details
• 0x22 - Read Data Block
• 0x23 - Write Data Block
• 0x30 - Settings: LED
• 0x31 - Settings: Buzzer
• 0x32 - Settings: Gain
• 0x33 - Settings: Query Frequency
• 0x34 - Settings: Mifare Key
• 0x35 - Settings: UID Case (KBD)
• 0x36 - Settings: UID Carriage Return (KBD)
• 0x37 - Settings: SAK (KBD)
• 0x38 - Settings: Scan Type
• 0x39 - Settings: Scan Block Number
• 0x3A - Settings: Output Format
• 0x3F - Settings: Save to ROM
• 0x40 - RFID Antenna State
• 0x41 - RFID Mode Control
• 0x80 - Reboot Device
• 0x81 - Reboot Device (DFU)
• Other values are RFU

Abberviations:

• IN - device to host
• OUT - host to device

Several commands have one 1byte parameter (bValue), that controls a device state or setting. It can be one of the following:

QUERY	0	query the current state/value
ON	1	enable
OFF	2	disable
SWITCH	3	switch state
DEFAULT	4	relinquish control to the firmware
-----	other values	treated as QUERY

Device Information

• Command code: 0x01
• Params (OUT): none
• Params (IN):
  • 4 bytes: error code
  • 1 byte: firmware info length
  • N bytes: firmware info

This command queries the firmware version of the device.

LED Control

• Command code: 0x02
• Params (OUT): bValue
  • ON - LED on
  • OFF - LED off
  • SWITCH- blink
  • DEFAULT - relinquish control to the firmware
  • other - query state
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current LED state (1 - on, 0 - off)

Buzzer Control

• Command code: 0x03
• Params (OUT): bValue
  • ON - buzzer on
  • OFF - buzzer off
  • SWITCH,DEFAULT - relinquish control to the firmware
  • other - query state
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current buzzer state (1 - on, 0 - off)

Inventory Scan (all tags)

Enumerates all the tags currently visible by the reader. All the tags are reset after the scan.

• Command code: 0x10
• Params(OUT): none

One or mode IN reports will be sent by the device. Params:

• 4 byte: error code
• 1 byte: L - UID length (0 for the last report)
• L bytes: UID
• 1 byte: SAK

Inventory Scan (the first tag)

Selects the first tag (according to the anti-collision procedure). The tag (if present) will be set as the current one and halted.

• Command code: 0x11
• Params (OUT): none
• Params (IN):
  • 4 bytes: error code
  • 1 byte: L - UID length
  • L bytes: UID
  • 1 byte: SAK

Inventory Scan (select the next tag)

Halts the currently selected tag (if any) and selects the next tag (if any) according to the anti-collision procedure. The new tag will be set as the current one and halted.

• Command code: 0x12
• Params (OUT): none
• Params (IN):
  • 4 bytes: error code
  • 1 byte: L - UID length
  • L bytes: UID
  • 1 byte: SAK

Check Tag Presence

Checks whether a tag with the specified UID is present. If the query succeeds, the tag will not be set as the current one. The tag will be halted.

• Command code: 0x13
• Params (OUT):
  • 1 byte: L - UID length (4/7/10)
  • L bytes: UID
• Params (IN):
  • 4 bytes: error code
  • 1 byte: L - UID length
  • L bytes: UID
  • 1 byte: SAK

Select Tag

The tag with the specified UID will be set as the current one and halted.

• Command code: 0x20
• Params (OUT):
  • 1 byte: L - UID length (0/4/7/10). If L == 0, halt the current tag.
  • L bytes: UID
• Params (IN):
  • 4 bytes: error code

Get Current Tag Information

If no tag is selected as the current one, the Inventory Scan (the first tag) command will be executed first. If the current tag fails to respond, the next one will be selected and queried.

• Command code: 0x21
• Params (OUT): none
• Params (IN):
  • 4 bytes: error code
  • 1 byte: L - UID length (0 for the last report)
  • L bytes: UID
  • 1 byte: SAK
  • 2 bytes: block count (16bit unsigned integer, little endian)
  • 1 byte: block size
  • 1 byte: tag type

Recognized tag types

• 0 - Classic 1K
• 1 - Classic 4K
• 2 - Classic Mini
• 3 - Ultralight
• 4 - Ultralight C
• 5 - Ultralight C EV1 (640 bits)
• 6 - Ultralight C EV1 (1312 bits)
• 7 - Plus S 2K
• 8 - Plus S 4K
• 9 - DesFire 2K
• 10 - DesFire 4K
• 11 - DesFire 8K
• 12 - Classic 2K
• 13 - Plus X 2K
• 14 - Plus X 4K
• 15-254 RFU
• 255 - Unknown

Read Data Block

A tag must be selected prior to executing this command (either by calling Inventory Scan (the first tag), Inventory Scan (select the next tag), Select Tag, or Tag Info ). The block number must be within the range supported by the tag.

• Command code: 0x22
• Params (OUT): 1 byte block number
• Params (IN):
  • 4 bytes: error code
  • 1 byte: block number
  • 1 byte: N = block size (16 or 4 - equal to the value of the block size field returned by the tag info command)
  • N bytes: block data

Write Data Block

A tag must be selected prior to executing this command (either by calling Inventory Scan (the first tag), Inventory Scan (select the next tag), Select Tag, or Tag Info ). The block number must be within the range supported by the tag. Data size must be equal to the block size value returned by the tag info command.

• Command code: 0x23
• Params (OUT):
  • 1 byte: block number
  • 1 byte: data size (N)
  • N bytes: data
• Params (IN):
  • 4 bytes: error code
  • 1 byte: block number

Device Settings

The following commands change various device settings. The are executed regardless of the scanning mode. Individual commands change only in-RAM settings. In order to save the current settings to ROM, execute the Settings Write command.

Enable/Disable the LED

This command enables/disables the LED. This setting only affects whether the firmware switches the LED when a tag is detected/lost. Regardless of this setting, you can switch the LED on and off using LED Control command.

• Command code: 0x30
• Params (OUT): bValue
  • ON - enable LED switching
  • OFF - disable LED switching
  • other - query the current setting
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current LED control setting (1 - enabled, 0 - disabled)

Enable/Disable the Buzzer

This command enables/disables the buzzer. This setting only affects whether the firmware switches the buzzer on when a tag is detected or not. Regardless of this setting, you can switch the buzzer on and off using BUZZ Control command.

• Command code: 0x31
• Params (OUT): bValue
  • ON - enable buzzer
  • OFF - mute buzzer
  • other - query the current setting
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current buzzer control setting (1 - enabled, 0 - disabled)

RFID Receiver Gain

The recevier gain is measured in dBm. The valid range is [18;48]dBm. The default value is 33dBm.

The valid gain values are

• 18dBm
• 23dBm
• 33dBm
• 38dBm
• 43dBm
• 48dBm

If any other value is passed, it will be rounded (to the nearest available value greater than the one passed).

• Command code: 0x32
• Params (OUT): (1 byte) 0 - query the current value, >0 - set new gain value (in dBm)
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current gain value in dBm.

Tag Presence Query Frequency

When in scanning mode, the device queries the tag presence every N ms (default value: 1000ms). This command controls the query frequency (i.e. the interval N). Valid range is [250-65535] ms. Values smaller than the minimum one will be accepted and silently increased to fit in the range. Values greater then the maximum one will result in an error.

• Command code: 0x33
• Params (OUT): (2 bytes - 16bit unsigned little endian integer) 0 - query the current value, >0 - set new interval value (in ms)
• Params (IN):
  • 4 bytes: error code
  • 2 bytea: the current interval value in ms.

Mifare Authentication Key

Mifare Classic tags need an authentication key to be read/written. The following command sets the key (the key type and 6 bytes long key itself), which will be used to authenticate connected Mifare Classic tags. The default value is FF

• Command code: 0x34
• Params (OUT):
  • 1 byte: key type - 'A' (ascii code 65) or 'B' (ascii code 66). Any other value - query the current key and key type.
  • 6 bytes: key
• Params (IN):
  • 1 byte: the current key type - 'A' (ascii code 65) or 'B' (ascii code 66)
  • 6 bytes: the current key

UID in Uppercase/Lowercase (keyboard mode)

• Command code: 0x35
• Params (OUT): bValue
  • ON - print UID in upper case
  • OFF - print UID in lower case
  • other - query the current setting
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current case control setting (1 - upper case, 0 - lower case)

Append/Omit Carriage Return (keyboard mode)

deprecated since version 1.2

• Command code: 0x36
• Params (OUT): bValue
  • ON - print carriage return after UID
  • OFF - do not print carriage return after UID
  • other - query the current setting
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current CR control setting (1 - append, 0 - omit)

Append/Omit SAK (keyboard mode)

deprecated since version 1.2

• Command code: 0x37
• Params (OUT): bValue
  • ON - append SAK to UID
  • OFF - do not append SAK to UID
  • other - query the current setting
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current SAK control setting (1 - append, 0 - omit)

Data selection (scanning mode)

deprecated since version 1.2

This setting controls data (UID or block) printed when a new tag is detected.

• Command code: 0x38
• Params (OUT): 1 byte value
  • 1 - print UID
  • 2 - print the contents of a block determined by the Block Number
  • other - query the current setting
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current value

Block number selection (scanning mode)

deprecated since version 1.2

In scanning mode the device continuously scans whether an RFID tag is present and prints UID or the selected block. This setting controls the block number being printed:

If the block does not exist or cannot be read (ex. due to an authorization failure) nothing is printed.

• Command code: 0x39
• Params (OUT):
  • 1 byte: 0 - query, >0 - set
  • 1 byte: new block number (if set mode is selected)
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current value

Set output format

supported since version 1.2

In scanning mode the device continuously scans whether an RFID tag is present and prints the data read from the discovered tag using the specified format.

Format string syntax:

• a - switch to ascii mode: output data as ascii symbols. Skips data outside the range 8(backspace), 9(tab), 10(return) and 32(space)-126(~).
• d - switch to decimal mode: output data as a decimal (0-255). No zero padding.
• h - switch to hexadecimal mode (lower-case)
• H - switch to hexadecimal mode (upper-case)
• U - output the tag UID. The 'U' switch must be followed by one of the modifiers:
  • * - output the whole UID
  • ~ - output the whole UID in reversed order (the last byte first)
  • n:m - output bytes n, n+1, ... m (incl.) of the UID. If m<n, output bytes m, m-1, ..., n(incl.). The indices outside the current data range are silently skipped.
  • n: - output bytes n, n+1, ... of the UID (till the last byte)
  • n - output byte n. (Attention: n,m indices start at zero!)
• BN - output block N(0-255) from the tag memory. The block numbers range depends on the tag type. If the block does not exist or cannot be read (for example due to the authentication failure), it is silently skipped. The B switch must be followed by the block number N, then the '%' symbol and one of the modifiers:
  • * - output the whole block (4 or 16 bytes depending on the tag type)
  • ~ - output the whole block in reversed order
  • n:m - output the block range (same format as the U modifier)
  • n: - output part of the block (same format as the U modifier)
  • n - output the block byte (same format as the U modifier)
• S - output the SAK of the tag
• \t sequence is converted to TAB, \n to RETURN.
• any other symbol is printed as is (no check whether is is a printable character or not is performed). In order to print reserved symbol ('a', 'd', 'h', etc) escape it with a backslash (\)

The default mode (i.e. before the first occurrence of a, d, h, or H switch) is the hexadecimal one. The upper or lower case depends on the Uppercase/Lowercase settings (code 0x35).

Syntax:

• Command code: 0x3A
• Params (OUT):
  • 1 byte: 0 - query, >0 - set
  • max. 32 bytes: format string (if less than 32 bytes must end with 0 (aka null-terminated string)
• Params (IN):
  • 4 bytes: error code
  • max 32 bytes: the current format string (null-terminated if less than 32 bytes long)

Write settings to ROM

This command saves the current in-RAM setting to ROM, i.e. makes them permanent

• Command code: 0x3F
• Params (OUT): none
• Params (IN): (4 bytes) error code

Device Control

The following commands control the RFID reader device itself:

Enable/Disable RF Field

• Command code: 0x40
• Params (OUT): bValue
  • ON - enable RF field
  • OFF - disable RF field
  • other - query the current mode
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current RF field state (1 - enabled, 0 - disabled)

RFID Mode Control

• Command code: 0x41
• Params (OUT): bValue
  • ON - enable scan mode
  • OFF - disable scan mode
  • QUERY - query the current mode
  • other - error (will return INVARG error)
• Params (IN):
  • 4 bytes: error code
  • 1 byte: current mode (1 - scan mode enabled, 0 - scan mode disabled)

Device Reboot

Reboot the device.

• Command code: 0x80
• Params (OUT): none
• Params (IN): (4 bytes) error code

Firmware Update

Reboot the device and start the bootloader (this command may not be supported by some devices. If not supported, acts as Device Reboot ).

• Command code: 0x81
• Params (OUT): none
• Params (IN): (4 bytes) error code

Other commands - RFU

*Params (IN) (4 bytes) error code 0x800 - Generic communication error.