User's Manual

11
May ’00 Chapter 1. Product Description
processor takes between 28 ms and 132 ms (typically 72 ms) before
it can receive new instructions via the serial communications
interface.
RXD (5) Input configured to receive serial data commands at 9600 Baud, 1
start bit, 8 data bits, no parity and 1 stop bit.
TXD (6) Output configured to transmit serial data at 9600 Baud, 1 start bit, 8
data bits, no parity and 1 stop bit.
GND (15, 25) Pins 15 and 25 are ground for the logic part.
ANT1 (16) Antenna pin for the connection of 47
µ
H, low Q antennas.
ANTCAP (17) It is possible to use antennas of lower inductance by connecting a
suitable capacitor between ANT1 and ANTCAP. This additional
capacitor (ceramic, 100 VDC) will be in parallel with the 30 nf
resonance capacitor on board the Micro-reader (see Figure 4 and
Appendix C).
ANT2 (19) Antenna pin (GND) for the connection of 47
µ
H, low Q antennas.
GNDP (21) Pin 21 is ground for the output stage.
VSP (22) Pin 22 is for connecting the positive supply voltage (5 V) for the
output stage.
VSL (24) Pin 24 is for connecting the positive supply voltage (5 V) for the logic
part.
CRDM (26) Supplying pin 26 with a logic high signal causes the Micro-reader to
run in a continuous charge-only read mode (see section 1.2.5
for
more information).
When the CRDM pin is tied to logic low, the Micro-reader is in an idle
state waiting for commands via the serial interface or for a trigger
signal (RDEN-) to start a single read out cycle. CRDM is a high
impedance input and must be tied to either VSL or GND via a
suitable resistor (27 kOhm).
WLSC (27) Pin 27 enables or disables wireless synchronization. To enable the
wireless synchronization, pin 27 must be taken to VSL. When
wireless synchronization is enabled, the Micro-reader will try to
synchronize its transmit signals with any other readers in range. To
disable wireless synchronization pin 27 must be taken to GND. Pin
27 is a high impedance input and must be tied to either VSL or GND
via a suitable resistor (27 kOhm).
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.
OKT (29) This output is set to logic high for approx. 60 ms if a valid
transponder was read. It can be connected to an LED externally to
indicate the result of the read cycle.
STAT(30) Pin 30 is set to logic low when the RF-transmitter is activated.
Supplying an external LED with this signal makes the status of the
Micro-reader visible.