Micro-reader Module
25 July 1996
2.1.3 Synchronization
There are two possible methods of wired synchronization:
1. Connect a pulse waveform to all RDEN- input pins of the Micro-readers to be synchronized.
The pulse would normally be at VSL, dropping to GND for 100
µ
s every 200 ms.
2. ‘Or’ all SYNC outputs together and then connect this as an input to RDEN- of each Micro-
reader to be synchronized.
Wireless synchronization of the Micro-reader is very effective at synchronizing to adjacent readers,
however problems may occur if the antennas are positioned such that a transponder can be within
range of two readers at the same time. In this situation one reader could synchronize with the
transponder instead of the other reader.
When the WLSC input is active the Micro-reader is in wireless synchronization mode. Wireless
synchronization can also be switched on/off by a corresponding command via the serial interface.
During execution of this command it has priority over the WLSC input. After the command
execution the status of the WLSC input will be considered again.
Note:
It is not recommended to have both wired and wireless synchronization switched on as
synchronization could be unreliable.
We recommend the use of bus drivers for wired synchronization with other Micro-readers
and to prevent ESD damage
.
Wired or wireless synchronization prolongs the cycle time by typically 20 ms.
2.1.4 Trigger Mode
When the Micro-reader is in idle mode it is possible to trigger a single charge-only read with a power
burst duration of 50 ms by taking the RDEN- pin to logic high for 100
µ
s. The single read will start
on the falling edge of the 100
µ
s pulse.
If a transponder command is sent to the Micro-reader via the SCI while RDEN- is in a logic high
state (waiting position), a falling edge would trigger execution of the command. In waiting position
the Micro-reader can only store one command. This means that if two commands were to be sent to
the Micro-reader while it is in the waiting position the second command will overwrite the first one.
2.1.5 Continuous Mode
When the CRDM input is active the Micro-reader goes into continuous charge-only read mode using
a power burst duration of 50 ms. The serial data input takes priority over the CRDM input such that
if a serial command is received it will be executed regardless of the state of the CRDM input. After
the execution of the serial data command the Micro-reader continues with the previous read mode.
