Pin Connection Description - Texas Instruments 2000 Series Reference Manual

Connector Pins

1.3.1 Pin Connection Description

SYNC (1) Output for wired synchronization. This output is at GND level until the Micro-reader starts
its read cycle, at which time it goes to VSL until the complete reading, programming or
locking cycle is finished.
RDEN- (2) Input for wired synchronization. Taking this pin to VSL acts as a hold-off for the
Micro-reader's output stage preventing it from transmitting until the input returns to GND.
The Micro-reader only samples this input at the start of its own reading, programming or
locking cycle, this means that if the input goes to VSL after a cycle is started, the cycle is
not interrupted. RDEN- is a high impedance input and must be tied to GND via a suitable
resistor (27 kΩ) when it is not being used.
When the Micro-reader is idle it is possible to trigger a single read by taking the
RDEN-pin logic high for 100 ms. The single read will start on the falling edge of the
100 ms pulse.
RESET- (4) Taking this pin to GND holds the Micro-reader in reset. If the reset pin is not used it can
be left disconnected as it is internally pulled up. Minimum pulse duration to perform a
reset is 1 ms. After a reset the 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.
Antenna pin for the connection of 47 µH, low Q antennas.
ANT1 (16)
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
and
Antenna pin (GND) for the connection of 47 µH, low Q antennas.
ANT2 (19)
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
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 kΩ).
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 kΩ).
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.
14 Product Description
Appendix C).
Section 1.2.5 for more information).
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Figure 1-4
SCBU027 – May 2000