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TRF7960, TRF7961
SLOU186G – AUGUST 2006 – REVISED MAY 2017
6.5.4 Transmission Without CRC
Same as
Section 6.5.3
6.5.5 Delayed Transmission With CRC
The transmission command must be sent first, followed by the transmission length bytes, and then the
FIFO data. The reader transmission is triggered by the TX timer.
6.5.6 Delayed Transmission Without CRC
Same as
Section 6.5.5
6.5.7 Transmit Next Time Slot
When this command is received, the reader transmits the next slot command. The next slot sign is defined
by the protocol selection. This command is used for ISO/IEC 15693 only.
6.5.8 Receiver Gain Adjust
This command should be executed when the MCU determines that no tag response is coming and when
the RF and receivers are on. When this command is received, the reader reads the digitized receiver
output. If more than two edges are observed in 100 µs, the window comparator voltage is increased. The
procedure is repeated until the number of edges (changes of logical state) of the digitized reception signal
is less than 2 (in 100 µs). The command can reduce the input sensitivity in 5-dB increments up to 15 dB.
This command ensures better operation in a noisy environment.
The gain setting is reset to maximum gain at EN = 0, POR = 1.
6.5.9 Test External RF (RSSI at RX Input With TX Off)
This command can be used in active mode when the RF receiver is on, and the RF output is off (rec-on,
bit B1 = 1 in the Chip Status Control register [see
antenna is measured and reported in the RSSI Levels register. The relation between the 3-bit code and
the external RF field strength (in A/m) must be determined by calculation or by experiments for each
antenna design. The antenna Q and connection to the RF input influence the result. The nominal
relationship between the RF peak-to-peak voltage at the receiver inputs and the corresponding RSSI level
is as follows.
Receiver Input (mV
):
PP
RSSI Level:
If the direct command Test RF Internal or Test RF External is used immediately after activation, the
command should be preceded by the Enable RX command to activate the RX section. For proper
execution of the test RF commands, the RX section must be enabled. This section is enabled
automatically when a data exchange between the reader and the tag is done, or by sending the Enable
RX direct command.
6.5.10 Test Internal RF (RSSI at RX Input With TX On)
This command measures the level of the RF carrier at the receive inputs. Its operating range is 300 mVp
to 2.1 Vp with a step size of 300 mV. The two values are displayed in the RSSI Levels register. The
command is intended for diagnostic purposes to set the correct RX_IN levels. The optimum RX_IN input
level is approximately 1.6 Vp, or an RSSI level of 5 or 6. The nominal relationship between the input RF
peak level and the corresponding RSSI code is as follows.
Receiver Input (mV
):
PP
RSSI Level:
32
Detailed Description
with CRC excluded.
with CRC excluded.
40
60
1
2
300
600
1
2
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Table
6-11]). The level of the RF signal received on the
80
100
140
3
4
900
1200
1500
3
4
Copyright © 2006–2017, Texas Instruments Incorporated
TRF7960 TRF7961
www.ti.com
180
300
5
6
7
1800
2100
5
6
7
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