25 July 1996
Micro-reader Module
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 pins 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 kOhm) 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
µ
s. The single read will start on the falling edge of the 100
µ
s 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.
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 2).
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.
