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SLOS758G – DECEMBER 2011 – REVISED MARCH 2020
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Detailed Description
Copyright © 2011–2020, Texas Instruments Incorporated
6.14.1.3.3 RSSI Levels and Oscillator Status Register (0x0F)
describes the bit fields of the RSSI Levels and Oscillator Status register. This register reports
the signal strength on both reception channels and RF amplitude during RF off conditions. The RSSI
values are valid from reception start until the start of the next transmission.
RSSI measurement block is measuring the demodulated envelope signal (except in case of direct
command for RF amplitude measurement described later in direct commands section). The measuring
system is latching the peak value, so the RSSI level can be read after the end of receive packet. The
RSSI value is reset during next transmit action of the reader, so the new tag response level can be
measured.
and
describe the RSSI levels calculated to RF_IN1 and
RF_IN2. The RSSI has 7 steps (3 bits) with 4-dB increment. The input level is the peak to peak
modulation level of RF signal measured on one side envelope (positive or negative).
Table 6-34. RSSI Levels and Oscillator Status Register (0x0F)
BIT NO.
BIT NAME
FUNCTION
DESCRIPTION
B7
Unused
B6
osc_ok
Crystal oscillator stable indicator
13.56-MHz frequency stable (approximately 200 µs)
B5
rssi_x2
MSB RSSI value of auxiliary RX
(RX_IN2)
Auxiliary channel is by default RX_IN2. The input can be swapped
by B3 = 1 (Chip State Control register). If "swapped", the auxiliary
channel is connected to RX_IN1 and the auxiliary RSSI represents
the signal level at RX_IN1.
B4
rssi_x1
Auxiliary channel RSSI
B3
rssi_x0
MSB RSSI value of auxiliary RX
(RX_IN2)
B2
rssi_2
MSB RSSI value of Main RX
(RX_IN1)
Active channel is the default and can be set with option bit B3 = 0 of
the Chip Status Control register (0x00).
B1
rssi_1
Main channel RSSI
B0
rssi_0
LSB RSSI value of Main RX
(RX_IN1)
