EM4022
Control ROM Bit definition
Parameter
Value
Fast / Normal
0
Mode
1
Free-running
0
1
ACK mode
0
1
Maximum
0
initial random
1
delay
2
3
4
5
6
7
Data rate
0
1
2
3
4
5
6
7
Encoding
0
method
1
GAP type
0
1
Mode
Normal
Fast
GAP detection enabled
GAP disabled (Free-running)
Slow-down
Switch-off
0 (Continuous)
16 bits
64 bits
256 bits
1 kbits
4 kbits
16 kbits
64 kbits
64 kbit/s
32 kbit/s
16 kbit/s
8 kbit/s
4 kbit/s
2 kbit/s
1 kbit/s
0.5 kbit/s
Glitch encoding
Manchester encoding
Low frequency GAP detection
High frequency GAP detection
Anti-collision Protocol Overview
The protocols are a collection of simple but fast and
reliable anti-collision protocols. They allow fast reading
of large numbers of transponders simultaneously using a
single reader. It is even possible to identify transponders
with identical codes, thereby making it possible to count
identical items.
Free-running protocol
The basis of the BTG-Supertag series of protocols is that
transponders transmit their own codes at random times
to a reader. By just listening and recording unique codes
when they are received, the reader can eventually detect
every tag. The reader detects collisions by typically
checking a CRC.
This basic protocol is known as the “Free-running”
protocol. It requires uniquely coded tags. Its main
advantage is that the reader design is simple, and the
spectrum requirement is much less – a very narrow band
is required.
Figure 10 shows a sequence of three transponders. The
reader starts first to read transponder 1 but during his
data transmission, transponder 3 starts to modulate. In
this case, due to the CRC check no transponder is
detected. A transponder is taken into account, if it
transmits a complete data stream without any
disturbance
Control ROM Map
15
14
13
12
11
Byte[1]
10
HF
GAP
9
Man-
chester
8
7
Data rate
6
5
4
3
Byte[0]
Random delay
2
1
0
Fast
Switch- Free-
off
running
Copyright
2002, EM Microelectronic-Marin SA
9
www.emmicroelectronic.com
EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
