Mifare 14443A - Page 8

Philips Semiconductors Rev. 1.0 November 2002
13.56 MHz RFID Proximity Antennas mifare
®
(14443A)
8 PUBLIC
data bit "0":
data bit "1":
3µs
9.44
µ
s
3µs
9.44
µ
s
previous bit "0"
modulated carrier
previous bit "1"
9.44
µ
s
Figure 4: Data Transmission PCD
Æ PICC, Miller Coding
The data rate of MIFARE
®
is 105.9KHz, so the length of a bit frame is 9.44µs. A pulse in the Miller coding
has a length of 3µs.
A logical ‘1’ is expressed with a pulse in the centre of the bit frame.
Two possibilities are given to code a logical ‘0’. This coding depends on the previous bit:
If the previous bit was a ‘0’, the following ‘0’ is expressed with a pulse of 3µs at in the first half of the next bit
frame.
If the previous bit was a ‘1’, the following ‘0’ is expressed without a pulse in the next bit frame.