Trigger Mode - Texas Instruments 2000 Series Reference Manual

Product Description

1.2.4 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 µs. The single read will start on the falling
edge of the 100 µs 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.
1.2.5 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.
In the default continuous read mode, only those valid RO, R/W or MPT IDs that differ from the previously
read ID; or valid IDs read after a "NO READ", are transferred via the SCI (Normal Mode). The
Micro-reader can be set to transfer all valid IDs that are read (Line Mode) by means of a corresponding
serial data command.
Without synchronization the Micro-reader has a reading frequency of approximately 10 readouts per
second using a power burst duration of 50 ms. Timing is given in more detail in
1.2.6 Serial Communication
The two serial I/O pins are configured for 9600 Baud, 1 start bit, 8 data bits, no parity and 1 stop bit; they
can be connected directly to a communications driver to allow a half duplex communication with a PC via
its serial communications interface (for example: RS232 or RS422).
The communications protocol is specified in
Handshake
The Micro-reader accepts handshake commands X
stops its current operation and stops transmitting data via the serial port. It stays in idle mode until X
(11 ) is received when it continues with the previous mode/command. During this idle period the
hex
Micro-reader accepts commands via the serial port, however, it waits for its execution until X
In this idle period the Micro-reader can store only one command.
Note: While receiving a command protocol from the serial port X
data without affecting the serial communication.
12 Product Description
Chapter 2.
/X . When it receives an X
on off
/X
on off
www.ti.com
Section 3.2.
(13 ) the Micro-reader
off hex
is received.
on
is interpreted as normal
SCBU027 – May 2000
Submit Documentation Feedback
on