40
SLOS758G – DECEMBER 2011 – REVISED MARCH 2020
Product Folder Links:
Detailed Description
Copyright © 2011–2020, Texas Instruments Incorporated
6.13.4 Transmission Without CRC (0x10)
The transmission command must be sent first, followed by transmission length bytes, and FIFO data. The
reader starts transmitting after the first byte is loaded into the FIFO. This is the same as described in
, except that the CRC is not included.
6.13.5 Block Receiver (0x16)
The block receiver command puts the digital part of receiver (bit decoder and framer) in reset mode. This
is useful in an extremely noisy environment, where the noise level could otherwise cause a constant
switching of the subcarrier input of the digital part of the receiver. The receiver (if not in reset) would try to
catch a SOF signal, and if the noise pattern matched the SOF pattern, an interrupt would be generated,
falsely signaling the start of an receive operation. A constant flow of interrupt requests can be a problem
for the external system (MCU), so the external system can stop this by putting the receive decoders in
reset mode.
The reset mode can be terminated in two ways:
The external system can send the enable receiver command (see
).
The reset mode is automatically terminated at the end of a transmit operation.
The receiver can stay in reset after end of transmit if the RX Wait Time register (0x08) is set. In this case,
the receiver is enabled at the end of the wait time following the transmit operation.
6.13.6 Enable Receiver (0x17)
This command clears the reset mode in the digital part of the receiver if the reset mode was entered by
the block receiver command.
6.13.7 Test Internal RF (RSSI at RX Input With TX On) (0x18)
The level of the RF carrier at RF_IN1 and RF_IN2 inputs is measured. THe operating range is 300 mV
P
to
2.1 V
P
(the step size is 300 mV). The two values are reported in the RSSI Levels register (0x0F). The
command is intended for diagnostic purposes to set correct RF_IN levels. Optimum RFIN input level is
approximately 1.6 V
P
or code 5 to 6. The nominal relationship between the RF peak level and RSSI code
is described in
and in
.
NOTE
If the command is executed immediately after power-up and before any communication with
tag was performed, the command must be preceded by the Enable RX command. The
Check RF commands require full operation, so the receiver must be activated by enable
receive or by a normal tag communication for the Check RF command to work properly.
Table 6-13. Test Internal RF
RF_IN1 (mV
P
):
300
600
900
1200
1500
1800
2100
Decimal Code:
1
2
3
4
5
6
7
Binary Code:
001
010
011
001
101
011
111
