SI4844-B20 Datasheet, PDF (18/27 Pages) Silicon Laboratories – BROADCAST ANALOG TUNING DIGITAL DISPLAY AM/FM/SW RADIO RECEIVER

Si4844-B20
5. Commands and Properties
Table 11. Si4844-B20 FM Receiver Command Summary
Cmd
Name
Description
0xE0
ATDD_GET_STATUS Get tune freq, band and etc status of the device.
0xE1
ATDD_POWER_UP
Power up device, band selection and band properties setup.
0xE2
ATDD_AUDIO_MODE Audio output mode: get/set audio mode and settings.
0x10
GET_REV
Returns the revision information of the device.
0x11
POWER_DOWN
Power down device.
0x12
SET_PROPERTY
Sets the value of a property.
0x13
GET_PROPERTY
Retrieve a property's value.
Note: The Si4844-B has its own power up and get status commands which are different from previous Si47xx tuner parts. To
differentiate, we use “ATDD_POWER_UP” and “ATDD_GET_STATUS” to denote the ATDD-specific commands
instead of the general Si47xx “POWER_UP” and “STATUS” commands.
Table 12. Si4844-B20 FM Receiver Property Summary
Prop
0x0201
0x0202
0x1100
0x1300
0x1301
0x1302
0x1303
0x1207
0x1800
0x1801
0x4000
Name
Description
Default
REFCLK_FREQ
Sets frequency of reference clock in Hz. The range is 31130 0x8000
to 34406 Hz, or 0 to disable the AFC. Default is 32768 Hz.
REFCLK_PRESCALE Sets the prescaler value for RCLK input.
0x0001
FM_DEEMPHASIS
Sets de-emphasis time constant. Default is 75 s.
0x0002
FM_SOFT_MUTE_RATE Sets the attack and decay rates when entering and leaving 0x0040
soft mute.
FM_SOFT_MUTE_SLOPE Configures attenuation slope during soft mute in dB attenua- 0x0002
tion per dB SNR below the soft mute SNR threshold. Default
value is 2.
FM_SOFT_MUTE_MAX_ Sets maximum attenuation during soft mute (dB). Set to 0 to 0x0010
ATTENUATION
disable soft mute. Default is 16 dB.
FM_SOFT_MUTE_
SNR_THRESHOLD
Sets SNR threshold to engage soft mute. Default is 4 dB.
0x0004
FM_STEREO_IND_
BLEND_THRESHOLD
Sets the blend threshold for stereo indicator. Default value is 0x9F
band-dependent (either 0x9F or 0xB2).
0xB2
FM_BLEND_RSSI_
STEREO_THRESHOLD
Sets RSSI threshold for stereo blend. (Full stereo above
threshold, blend below threshold.) To force stereo, set this to
0. To force mono, set this to 127. Default value is 49 dBV.
0x0031
FM_BLEND_RSSI_
MONO_THRESHOLD
Sets RSSI threshold for mono blend (Full mono below
threshold, blend above threshold). To force stereo, set this to
0. To force mono, set this to 127. Default value is band-
dependent (either 8 or 7).
0x0008
0x0007
RX_VOLUME
Sets the output volume.
0x003F
18
Rev. 1.0