Wiegand Protocol Description - VISUAL PLUS xpr BIOXR-SW User Manual

Company
a Visual Plus Corporation

10 Wiegand protocol description

The data is sent over the lines DATA 0 for the logic "0" and DATA 1 for the logic "1". Both lines use inverted logic,
meaning that a pulse low on DATA 0 indicates a "0" and a pulse low on DATA 1 indicates a "1".When the lines are high,
no data is being sent. Only 1 of the 2 lines ( DATA 0 / DATA 1 ) can pulse at the same time.
Example: data 0010....
Data bit 0 = approximately 75 us (microseconds)
Data bit 1 = approximately 75 us (microseconds)
Time between two data bits: approximately 1 ms (millisecond). Both data lines (D0 and D1) are high.
Description for the 26 bits Wiegand format
Each data block consists of a first parity bit P1, a fixed 8 bits header, 16 bits of user code and a 2nd parity bit P2. Such a
data block is shown bellow:
Parity bit (bit 1) + 8 bits header
P1 XXXXXXXX
Example:
1 1 0 1 0 1 0 1 0
Note: Parity bits are calculated as follows:
P1 = even parity calculated over the bits 2 to 13 (X)
P2 = odd parity calculated over the bits 14 to 25 (Y)
+ 16 bits user code = 2 bytes
XXXXYYYY YYYYYYYY
170
0 1 1 1
Biometric Readers with swipe capacitive sensor v2.0
+ Parity bit (bit 26)
P2
31527
1 0 1 1 0 0 1 0 0 1 1 1 0
28