User's Manual

ACR122L-ACS Design Specification

Version 0.03 19/05/2010

Page

ACR122L

ACS

5.0. Serial Interface (CCID-liked FRAME Format)

Communication setting: 9600 bps, 8-N-1

The communication protocol between the Host and ACR122L is very similar to the CCID protocol.

ACR122L Command Frame Format

STX Bulk-OUT Header APDU Command

Parameters

Checksum

ETX

1 Byte 10 Bytes M Bytes

(If applicable)

1 Byte 1 Byte

ACR122L Status Frame Format

STX Status Checksun ETX

1 Byte 1 Byte 1 Byte 1 Byte

ACR122L Response Frame Format

STX Bulk-IN Header APDU Response

abData

Checksun

ETX

1 Byte 10 Bytes N Bytes

(If applicable)

1 Byte 1 Byte

Checksum = XOR {Bulk-OUT Header, APDU Command or Parameters}

Checksum = XOR {Bulk-IN Header, APDU Response or abData}

For control SAM Socket 1, the STX must be equal to 0x02 and ETX must be equal to 0x03.

For control SAM Socket 2, the STX must be equal to 0x12 and ETX must be equal to 0x13.

For control SAM Socket 3, the STX must be equal to 0x22 and ETX must be equal to 0x23.

For control access contactless interface, peripherals (i.e. LEDs, LCD and Buzzer), the STX must be

equal to 0x02 and ETX must be equal to 0x03, which is the same with control SAM Socket1.

In general, we would make use of three types of Bulk-OUT Header.

• HOST_to_RDR_IccPowerOn: To activate the SAM interface. The ATR of the SAM will be

returned if available.

• HOST_to_RDR_IccPowerOff: To deactivate the SAM interface.

• HOST_to_RDR_XfrBlock: To exchange APDUs between the Host and ACR122L.

#The SAM1 interface must be activated in order to use the Contactless interface and Peripherals. In

short, all the APDUs are exchanged through the SAM1 Interface.

Similarly, two types of Bulk-IN Header are used.

• RDR_to_HOST_DataBlock: In response to the “HOST_to_RDR_IccPowerOn” and

“HOST_to_RDR_XfrBlock” Frames.

• RDR_to_HOST_SlotStatus: In response to the “HOST_to_RDR_IccPowerOff” Frame.