Advanced Card ACR122S, User Manual

Page: 39 / 57

ACR122S – Communication Protocol
info@acs.com.hk
Version 2.01
www.acs.com.hk
Page 39 of 57
6.7.1. Handling the value blocks of Mifare 1K/4K tag?
The value blocks are used for performing electronic purse functions (Increment, Decrement, Restore,
Transfer, etc). These value blocks have a fixed data format which permits error detection and
correction and a backup management.
Byte Number 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Description Value
______
Value
Value
Adr
___
Adr Adr
___
Adr
Where:
Value A signed 4-byte value. The lowest significant byte off a value is stored in the
lowest address byte. Negative values are stored in standard 2’s complement
format.
Adr 1-Byte address, which can be used to save the storage address of a block.
(optional).
Example:
Value 100 (decimal) = 64 (Hex), assume Block = 05h
The formatted value block = 64 00 00 00 9B FF FF FF 64 00 00 00 05 FA 05 FA
Step 1. Update the content of Block
05 with a value 100 (dec) .
HOST -> 02 6F 1A 00 00 00 00 01 00 00 00
HOST -> FF 00 00 00 15 D4 40
01 A0 05 64 00 00 00 9B FF FF FF 64 00 00 00 05 FA 05 FA
[Checksum] 03
RDR -> 02 00 00 03 (Waiting the Tag)
RDR -> 02 80 05 00 00 00 00 01 01 00 00
RDR -> D5 41 [00] 90 00 [Checksum] 03
Step 2. Increment the value of Block
05 by 1 (dec) .
HOST -> 02 6F 0E 00 00 00 00 01 00 00 00
HOST -> FF 00 00 00 09 D4 40
01 C1 05 01 00 00 00 [Checksum] 03
RDR -> 02 00 00 03 (Waiting the Tag)
RDR -> 02 80 05 00 00 00 00 01 01 00 00
RDR -> D5 41 [00] 90 00 [Checksum] 03
Note: Decrement the value of Block 05 by 1 (dec) .
HOST -> FF 00 00 00 09 D4 40 01 C0 05 01 00 00 00
Step 3. Transfer the prior calculated value of Block
05 (dec) .
HOST -> 02 6F 0A 00 00 00 00 01 00 00 00
HOST -> FF 00 00 00 05 D4 40
01 B0 05 [Checksum] 03