SLOS787H – MAY 2012 – REVISED APRIL 2014
6.13.3.3.3 RSSI Levels and Oscillator Status Register (0x0F)
Table 6-40. RSSI Levels and Oscillator Status Register (0x0F)
Function:
Displays the signal strength on both reception channels and RF amplitude during RF-off state. The RSSI values are valid from
reception start till start of next transmission.
Bit
Name
Function
Description
B7
Unused
Crystal oscillator stable
B6
osc_ok
13.56-MHz frequency stable (
≈
200 µs)
indicator
MSB RSSI value of auxiliary
B5
rssi_x2
Auxiliary channel is by default RX_IN2. The input can be swapped by B3 = 1
RX (RX_IN2)
(Chip State Control register 0x00). If "swapped", the Auxiliary channel is
B4
rssi_x1
Auxiliary channel RSSI
connected to RX_IN1 and, hence, the Auxiliary RSSI represents the signal level
MSB RSSI value of auxiliary at RX_IN2.
B3
rssi_x0
RX (RX_IN2)
MSB RSSI value of main
B2
rssi_2
RX (RX_IN1)
Active channel is default and can be set with option bit B3 = 0 of chip state
B1
rssi_1
Main channel RSSI
control register 0x00.
LSB RSSI value of main RX
B0
rssi_0
(RX_IN1)
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. The RSSI levels calculated to the RF_IN1 and RF_IN2 are presented in
and
. 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).
6.13.3.3.4 Special Functions Register (0x10)
Table 6-41. Special Functions Register (0x10)
Function:
User configurable options for ISO14443A specific operations
Bit
Name
Function
Description
B7
Reserved
Reserved
B6
Reserved
Reserved
Disables parity checking for
B5
par43
ISO14443A
0 = 18.88 µs
B4
next_slot_37us
Sets the time grid for next slot command in ISO15693
1 = 37.77 µs
Bit stream transmit for
Enables direct mode for transmitting ISO14443A data, bypassing the FIFO and
B3
Sp_dir_mode
MIFARE at 106 kbps
feeding the data bit stream directly onto the encoder.
0 = normal receive
Enable 4-bit replay for example, ACK, NACK used by some cards; for example,
B2
4_bit_RX
1 = 4-bit receive
MIFARE Ultralight
0 = anticollision framing
(0x93, 0x95, 0x97)
Disable anticollision frames for 14443A (this bit should be set to 1 after
B1
14_anticoll
1 = normal framing (no
anticollision is finished)
broken bytes)
0 = 7 subcarrier pulses
Selects the number of subcarrier pulses that trigger collision error in the
B0
col_7_6
1 = 6 subcarrier pulses
14443A - 106 kbps
Copyright © 2012–2014, Texas Instruments Incorporated
Detailed Description
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