SI4720-B20 Datasheet, PDF (37/48 Pages) Silicon Laboratories – BROADCAST FM RADIO TRANSCEIVER FOR PORTABLE APPLICATIONS

Si4720/21-B20
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Table 20. Si472x Command Summary (Continued)
FM_RDS_STATUS
FM_AGC_STATUS
FM_AGC_OVERRIDE
GPIO_CTL
GPIO_SET
Returns RDS information for current channel and reads an entry
from RDS FIFO (Si4721 only).
Queries the current AGC settings
Override AGC setting by disabling and forcing it to a fixed value
Configures GPO1, 2, and 3 as output or Hi-Z.
Sets GPO1, 2, and 3 output level (low or high).
Table 21. Si472x Property Summary
Prop
Name
Description
Default
Transmit Properties
0x0001
GPO_IEN
Enables interrupt sources.
0x0000
0x0101
0x0103
0x0201
DIGITAL_INPUT _FORMAT Configures the digital input format.
DIGITAL_INPUT _SAMPLE_RATE
Configures the digital input sample rate in 1 Hz steps.
Default is 0.
REFCLK_FREQ
Sets frequency of the reference clock in Hz. The range is
31130 to 34406 Hz, or 0 to disable the AFC. Default is
32768 Hz.
0x0000
0x0000
0x8000
0x0202
REFCLK_PRESCALE
Sets the prescaler value for the reference clock.
0x0001
0x2100
TX_COMPONENT_ENABLE
Enable transmit multiplex signal components.
Default has pilot and L-R enabled.
0x0003
0x2101
0x2102
TX_AUDIO_DEVIATION
TX_PILOT_DEVIATION
Configures audio frequency deviation level. Units are in
10 Hz increments. Default is 6825 (68.25 kHz).
Configures pilot tone frequency deviation level. Units are
in 10 Hz increments. Default is 675 (6.75 kHz)
0x1AA9
0x02A3
0x2103
0x2104
0x2105
0x2106
TX_RDS_DEVIATION
TX_LINE_INPUT_LEVEL
TX_LINE_INPUT_MUTE
TX_PREEMPHASIS
Si4721 Only. Configures the RDS/RBDS frequency
deviation level. Units are in 10 Hz increments. Default is
2 kHz.
Configures maximum analog line input level to the
LIN/RIN pins to reach the maximum deviation level pro-
grammed into the audio deviation property TX Audio
Deviation. Default is 636 mV_PK.
Sets line input mute. L and R inputs may be inde-
pendently muted. Default is not muted.
Configures pre-emphasis time constant.
Default is 0 (75 µS).
0x00C8
0x327C
0x0000
0x0000
0x2107
0x2200
0x2201
TX_PILOT_FREQUENCY
TX_ACOMP_ENABLE
TX_ACOMP_THRESHOLD
Configures the frequency of the stereo pilot. Default is
19000 Hz.
Enables audio dynamic range control and limiter.
Default is 2 (limiter is enabled, audio dynamic range
control is disabled).
Sets the threshold level for audio dynamic range control.
Default is –40 dB.
0x4A38
0x0002
0xFFD8
0x2202
TX_ACOMP_ATTACK_TIME
Sets the attack time for audio dynamic range control.
Default is 0 (0.5 ms).
0x0000
Rev. 1.0
37