Silicon Laboratories Si47 Series Operating instructions

Rev. 0.8 12/11 Copyright © 2011 by Silicon Laboratories AN332
AN332
Si47XX PROGRAMMING GUIDE
1. Introduction
This document provides an overview of the programming requirements for the Si4704/05/06/07/1x/2x/3x/4x/84/85
FM transmitter/AM/FM/SW/LW/WB receiver. The hardware control interface and software commands are detailed
along with several examples of the required steps to configure the device for various modes of operation.
2. Overview
This family of products is programmed using commands and responses. To perform an action, the system
controller writes a command byte and associated arguments, causing the device to execute the given command.
The device will, in turn, provide a response depending on the type of command that was sent. Section "4.
Commands and Responses" on page 6 and section "5. Commands and Properties" on page 7 describe the
procedures for using commands and responses and provide complete lists of commands, properties, and
responses.
The device has a slave control interface that allows the system controller to send commands to and receive
responses from the device using one of three serial protocols (or bus modes): 2-wire mode (I2C and SMBUS
compatible), 3-wire mode, or SPI mode.
Section "6. Control Interface" on page 224 describes the control interface in detail.
Section "7. Powerup" on page 232 describes options for the sequencing of VDD and VIO power supplies, selection
of the desired bus mode, provision of the reference clock, RCLK, and sending of the POWER_UP command.
Section "8. Powerdown" on page 239 describes sending the POWER_DOWN command and removing VDD and
VIO power supplies as necessary.
Section "9. Digital Audio Interface" on page 240 describes the digital audio format supported and how to operate
the device in digital mode.
Section "10. Timing" on page 243 describes the CTS (Clear to Send) timing indicating when the command has
been accepted and in most cases completed execution, and the STC (Seek/Tune Complete) timing indicating
when the Seek/Tune commands have completed execution.
Section "11. FM Transmitter" on page 249 describes the audio dynamic range control, limiter, pre-emphasis,
recommendations for maximizing audio volume for the FM transmitter.
Section "12. Programming Examples" on page 253 provides flowcharts and step-by-step procedures for
programming the device.

AN332
2 Rev. 0.8
Table 1. Product Family Function
Part
Number General Description
FM Transmitter
FM Receiver
AM Receiver
SW/LW Receiver
WB Receiver
RDS
High Performance RDS
RPS
SAME
Digital Input
Digital Output
Embedded FM antenna
AEC-Q100 Qualified
Package Size (mm)
Si4700 FM Receiver 4x4
Si4701 FM Receiver with RDS  4x4
Si4702 FM Receiver 3x3
Si4703 FM Receiver with RDS  3x3
Si4704 FM Receiver  3x3
Si4705 FM Receiver with RDS 
2 3x3
Si47061High Performance RDS Receiver 
3x3
Si47071WB Receiver with SAME  3x3
Si4708 FM Receiver 2.5x2.5
Si4709 FM Receiver with RDS  2.5x2.5
Si4710 FM Transmitter  3x3
Si4711 FM Transmitter with RDS  3x3
Si4712 FM Transmitter with RPS   3x3
Si4713 FM Transmitter with RDS & RPS   3x3
Si4720 FM Transceiver   3x3
Si4721 FM Transceiver with RDS     3x3
Si4730 AM/FM Receiver  3x3
Si4731 AM/FM Receiver with RDS  
23x3
Si4734 AM/SW/LW/FM Receiver  3x3
Si4735 AM/SW/LW/FM Receiver with RDS  
23x3
Si4736 AM/FM/WB Receiver   3x3
Si4737 AM/FM/WB Receiver with RDS    3x3
Si4738 FM/WB Receiver  3x3
Si4739 FM/WB Receiver with RDS   3x3
Si47401AM/FM Receiver   4x4
Notes:
1. Si4706, Si4707, and Si474x are covered under NDA.
2. High Performance RDS is available in Si4705/31/35/85-D50 and later.

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Rev. 0.8 3
Si47411AM/FM Receiver with RDS     4x4
Si47421AM/LW/SW/FM/WB Receiver    4x4
Si47431AM/LW/SW/FM/WB Receiver with
RDS     4x4
Si47441AM/LW/SW/FM Receiver   4x4
Si47451AM/LW/SW/FM Receiver with RDS     4x4
Si47491High-Performance RDS Receiver   4x4
Si4784 FM Receiver  3x3
Si4785 FM Receiver with RDS 
23x3
Table 1. Product Family Function (Continued)
Notes:
1. Si4706, Si4707, and Si474x are covered under NDA.
2. High Performance RDS is available in Si4705/31/35/85-D50 and later.

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4 Rev. 0.8
TABLE OF CONTENTS
Section Page
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
4. Commands and Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
5. Commands and Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
5.1. Commands and Properties for the FM/RDS Transmitter (Si4710/11/12/13/20/21) . . .7
5.2. Commands and Properties for the FM/RDS Receiver
(Si4704/05/06/2x/3x/4x/84/85) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
5.3. Commands and Properties for the AM/SW/LW Receiver
(Si4730/31/34/35/36/37/40/41/42/43/44/45) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124
5.4. Commands and Properties for the WB Receiver (Si4707/36/37/38/39/42/43) . . . .172
5.5. Commands and Properties for the Stereo Audio ADC Mode
(Si4704/05/30/31/34/35) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206
6. Control Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224
6.1. 2-Wire Control Interface Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224
6.2. 3-Wire Control Interface Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .227
6.3. SPI Control Interface Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .230
7. Powerup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .232
7.1. Powerup from Device Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .233
7.2. Powerup from a Component Patch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .234
8. Powerdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .239
9. Digital Audio Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .240
10. Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243
11. FM Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249
11.1. Audio Dynamic Range Control for FM Transmitter . . . . . . . . . . . . . . . . . . . . . . . .249
11.2. Audio Pre-emphasis for FM Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .250
11.3. Audio Limiter for FM Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251
11.4. Maximizing Audio Volume for FM Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
12. Programming Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .253
12.1. Programming Example for the FM/RDS Transmitter . . . . . . . . . . . . . . . . . . . . . .253
12.2. Programming Example for the FM/RDS Receiver . . . . . . . . . . . . . . . . . . . . . . . .271
12.3. Programming Example for the AM/LW/SW Receiver . . . . . . . . . . . . . . . . . . . . . .293
12.4. Programming Example for the WB/SAME Receiver . . . . . . . . . . . . . . . . . . . . . . .303
Appendix A—Comparison of the Si4704/05/3x-B20, Si4704/05/3x-C40, and
Si4704/05/3x-D60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .312
Appendix B—Si4704/05/3x-B20/-C40/-D60 Compatibility Checklist . . . . . . . . . . . . . . . .316
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .319
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .320

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Rev. 0.8 5
3. Terminology
SEN—Serial enable pin, active low; used as device select in 3-wire and SPI operation and address selection in
2-wire operation.
SDIO—Serial data in/data out pin.
SCLK—Serial clock pin.
RST or RSTb—Reset pin, active low
RCLK—External reference clock
GPO—General purpose output
CTS—Clear to send
STC—Seek/Tune Complete
NVM—Non-volatile internal device memory
Device—Refers to the FM Transmitter/AM/FM/SW/LW/WB Receiver
System Controller—Refers to the system microcontroller
CMD—Command byte
COMMANDn—Command register (16-bit) in 3-Wire mode (n = 1 to 4)
ARGn—Argument byte (n = 1 to 7)
STATUS—Status byte
RESPn—Response byte (n = 1 to 15)
RESPONSEn—Response register (16-bit) in 3-Wire mode (n = 1 to 8)

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6 Rev. 0.8
4. Commands and Responses
Commands control actions, such as power up, power down, or tune to a frequency, and are one byte in size.
Arguments are specific to a given command and are used to modify the command. For example, after the
TX_TUNE_FREQ command, arguments are required to set the tune frequency. Arguments are one byte in size,
and each command may require up to seven arguments. Responses provide the system controller status
information and are returned after a command and its associated arguments are issued. All commands return a
one byte status indicating interrupt state and clear-to-send the next command. Commands may return up to 15
additional response bytes. A complete list of commands is available in “5. Commands and Properties”.
Table 2 shows an example of tuning to a frequency using the TX_TUNE_FREQ command. This command requires
that a command and three arguments be sent and returns one status byte. The table is broken into three columns.
The first column lists the action taking place: command (CMD), argument (ARG), status (STATUS), or response
(RESP). The second column lists the data byte or bytes in hexadecimal that are being sent or received. An arrow
preceding the data indicates data being sent from the device to the system controller. The third column describes
the action.
Properties are special command arguments used to modify the default device operation and are generally
configured immediately after power-up. Examples of properties are TX _PREEMPHASIS and REFCLK_FREQ. A
complete list of properties is available in “5. Commands and Properties”.
Table 3 shows an example of setting the REFCLK frequency using the REFCLK_FREQ property by sending the
SET_PROPERTY command and five argument bytes. ARG1 of the SET_PROPERTY command is always 0x00.
ARG2 and ARG3 are used to select the property number, PROP (0x0201 in this example), and ARG4 and ARG5
are used to set the property value, PROPD (0x8000 or 32768 Hz in the example).
The implementation of the command and response procedures in the system controller differs for each of the three
bus modes. Section "6. Control Interface" on page 224 details the required bit transactions on the control bus for
each of the bus modes.
Table 2. Using the TX_TUNE_FREQ Command
Action Data Description
CMD 0x30 TX_TUNE_FREQ
ARG1 0x00
ARG2 0x27 Set Station to 101.1 MHz
ARG3 0x7E (0x277E = 10110 with 10 kHz step size)
STATUS 0x80 Reply Status. Clear-to-send high.
Table 3. Using the SET_PROPERTY Command
Action Data Description
CMD 0x12 SET_PROPERTY
ARG1 0x00
ARG2 (PROP) 0x02 REFCLK_FREQ
ARG3 (PROP) 0x01
ARG4 (PROPD) 0x80 32768 Hz
ARG5 (PROPD) 0x00
STATUS 0x80 Reply Status. Clear-to-send high.

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Rev. 0.8 7
5. Commands and Properties
There are four different components for these product families:
1. FM Transmitter component
2. FM Receiver component
3. AM/SW/LW component
4. WB component
The following four subsections list all the commands and properties used by each of the component.
5.1. Commands and Properties for the FM/RDS Transmitter (Si4710/11/12/13/20/21)
The following two tables are the summary of the commands and properties for the FM/RDS Transmitter component
applicable to Si4710/11/12/13/20/21.
Table 4. FM/RDS Transmitter Command Summary
Cmd Name Description Available In
0x01 POWER_UP Power up device and mode selection. Modes include FM
transmit and analog/digital audio interface configuration. All
0x10 GET_REV Returns revision information on the device. All
0x11 POWER_DOWN Power down device. All
0x12 SET_PROPERTY Sets the value of a property. All
0x13 GET_PROPERTY Retrieves a property’s value. All
0x14 GET_INT_STATUS Read interrupt status bits. All
0x15 PATCH_ARGS* Reserved command used for patch file downloads. All
0x16 PATCH_DATA* Reserved command used for patch file downloads. All
0x30 TX_TUNE_FREQ Tunes to given transmit frequency. All
0x31 TX_TUNE_POWER Sets the output power level and tunes the antenna capaci-
tor. All
0x32 TX_TUNE_MEASURE Measure the received noise level at the specified fre-
quency.
Si4712/13/20
/21
0x33 TX_TUNE_STATUS Queries the status of a previously sent TX Tune Freq, TX
Tune Power, or TX Tune Measure command. All
0x34 TX_ASQ_STATUS Queries the TX status and input audio signal metrics. All
0x35 TX_RDS_BUFF Queries the status of the RDS Group Buffer and loads
new data into buffer. Si4711/13/21
0x36 TX_RDS_PS Set up default PS strings. Si4711/13/21
0x80 GPIO_CTL Configures GPO1, 2, and 3 as output or Hi-Z. All except
Si4710-A10
0x81 GPIO_SET Sets GPO1, 2, and 3 output level (low or high). All except
Si4710-A10
*Note: Commands PATCH_ARGS and PATCH_DATA are only used to patch firmware. For information on applying a patch
file, see "7.2. Powerup from a Component Patch" on page 234.

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8 Rev. 0.8
Table 5. FM Transmitter Property Summary
Prop Name Description Default Available In
0x0001 GPO_IEN Enables interrupt sources. 0x0000 All
0x0101 DIGITAL_INPUT _FORMAT1Configures the digital input format. 0x0000 All except
Si4710-A10
0x0103 DIGITAL_INPUT _SAMPLE_RATE1
Configures the digital input sample
rate in 1 Hz steps.
Default is 0.
0x0000 All except
Si4710-A10
0x0201 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.
0x8000 All
0x0202 REFCLK_PRESCALE Sets the prescaler value for the refer-
ence clock. 0x0001 All
0x2100 TX_COMPONENT_ENABLE
Enable transmit multiplex signal com-
ponents.
Default has pilot and L-R enabled.
0x0003 All
0x2101 TX_AUDIO_DEVIATION
Configures audio frequency deviation
level. Units are in 10 Hz increments.
Default is 6825 (68.25 kHz).
0x1AA9 All
0x2102 TX_PILOT_DEVIATION
Configures pilot tone frequency devi-
ation level. Units are in 10 Hz incre-
ments. Default is 675 (6.75 kHz)
0x02A3 All
0x2103 TX_RDS_DEVIATION2
Configures the RDS/RBDS fre-
quency deviation level. Units are in
10 Hz increments. Default is 2 kHz.
0x00C8 Si4711/13/21
0x2104 TX_LINE_INPUT_LEVEL
Configures maximum analog line
input level to the LIN/RIN pins to
reach the maximum deviation level
programmed into the audio deviation
property TX Audio Deviation. Default
is 636 mVPK.
0x327C All
0x2105 TX_LINE_INPUT_MUTE
Sets line input mute. L and R inputs
may be independently muted. Default
is not muted.
0x0000 All
0x2106 TX_PREEMPHASIS
Configures pre-emphasis time con-
stant.
Default is 0 (75 µs).
0x0000 All
0x2107 TX_PILOT_FREQUENCY Configures the frequency of the ste-
reo pilot. Default is 19000 Hz. 0x4A38 All
Notes:
1. Digital Audio Input feature (property DIGITAL_INPUT_FORMAT and DIGITAL_INPUT_SAMPLE_RATE) is supported
in FMTX component 2.0 or later.
2. RDS feature (command TX_RDS_BUFF, TX_RDS_PS and RDS properties 0x2103, 0x2C00 through 2C07) is
supported in FMTX component 2.0 or later.
3. Limiter feature (LIMITEN bit in TX_ACOMP_ENABLE and property TX_LIMITER_RELEASE_TIME) is supported in
FMTX component 2.0 or later.

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Rev. 0.8 9
0x2200 TX_ACOMP_ENABLE3
Enables audio dynamic range control
and limiter.
Default is 2 (limiter is enabled, audio
dynamic range control is disabled).
0x0002 All
0x2201 TX_ACOMP_THRESHOLD
Sets the threshold level for audio
dynamic range control.
Default is –40 dB.
0xFFD8 All
0x2202 TX_ACOMP_ATTACK_TIME
Sets the attack time for audio
dynamic range control.
Default is 0 (0.5 ms).
0x0000 All
0x2203 TX_ACOMP_RELEASE_TIME
Sets the release time for audio
dynamic range control.
Default is 4 (1000 ms).
0x0004 All
0x2204 TX_ACOMP_GAIN
Sets the gain for audio dynamic
range control.
Default is 15 dB.
0x000F All
0x2205 TX_LIMITER_RELEASE_TIME3Sets the limiter release time. Default
is 102 (5.01 ms) 0x0066 All except Si4710-A10
0x2300 TX_ASQ_INTERRUPT_SOURCE
Configures measurements related to
signal quality metrics. Default is none
selected.
0x0000 All
0x2301 TX_ASQ_LEVEL_LOW
Configures low audio input level
detection threshold. This threshold
can be used to detect silence on the
incoming audio.
0x0000 All
0x2302 TX_ASQ_DURATION_LOW
Configures the duration which the
input audio level must be below the
low threshold in order to detect a low
audio condition.
0x0000 All
0x2303 TX_ASQ_LEVEL_HIGH
Configures high audio input level
detection threshold. This threshold
can be used to detect activity on the
incoming audio.
0x0000 All
0x2304 TX_ASQ_DURATION_HIGH
Configures the duration which the
input audio level must be above the
high threshold in order to detect a
high audio condition.
0x0000 All
0x2C00 TX_RDS_INTERRUPT_SOURCE2Configure RDS interrupt sources.
Default is none selected. 0x0000 Si4711/13/21
Table 5. FM Transmitter Property Summary (Continued)
Prop Name Description Default Available In
Notes:
1. Digital Audio Input feature (property DIGITAL_INPUT_FORMAT and DIGITAL_INPUT_SAMPLE_RATE) is supported
in FMTX component 2.0 or later.
2. RDS feature (command TX_RDS_BUFF, TX_RDS_PS and RDS properties 0x2103, 0x2C00 through 2C07) is
supported in FMTX component 2.0 or later.
3. Limiter feature (LIMITEN bit in TX_ACOMP_ENABLE and property TX_LIMITER_RELEASE_TIME) is supported in
FMTX component 2.0 or later.

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10 Rev. 0.8
0x2C01 TX_RDS_PI2Sets transmit RDS program identifier. 0x40A7 Si4711/13/21
0x2C02 TX_RDS_PS_MIX2Configures mix of RDS PS Group
with RDS Group Buffer. 0x0003 Si4711/13/21
0x2C03 TX_RDS_PS_MISC2Miscellaneous bits to transmit along
with RDS_PS Groups. 0x1008 Si4711/13/21
0x2C04 TX_RDS_PS_REPEAT_COUNT2
Number of times to repeat transmis-
sion of a PS message before trans-
mitting the next PS message.
0x0003 Si4711/13/21
0x2C05 TX_RDS_PS_MESSAGE_COUNT2Number of PS messages in use. 0x0001 Si4711/13/21
0x2C06 TX_RDS_PS_AF2
RDS Program Service Alternate Fre-
quency. This provides the ability to
inform the receiver of a single alter-
nate frequency using AF Method A
coding and is transmitted along with
the RDS_PS Groups.
0xE0E0 Si4711/13/21
0x2C07 TX_RDS_FIFO_SIZE2
Number of blocks reserved for the
FIFO. Note that the value written
must be one larger than the desired
FIFO size.
0x0000 Si4711/13/21
Table 5. FM Transmitter Property Summary (Continued)
Prop Name Description Default Available In
Notes:
1. Digital Audio Input feature (property DIGITAL_INPUT_FORMAT and DIGITAL_INPUT_SAMPLE_RATE) is supported
in FMTX component 2.0 or later.
2. RDS feature (command TX_RDS_BUFF, TX_RDS_PS and RDS properties 0x2103, 0x2C00 through 2C07) is
supported in FMTX component 2.0 or later.
3. Limiter feature (LIMITEN bit in TX_ACOMP_ENABLE and property TX_LIMITER_RELEASE_TIME) is supported in
FMTX component 2.0 or later.

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Rev. 0.8 11
Table 6. Status Response
BitD7D6D5D4D3D2D1D0
STATUS CTS ERR X X X RDSINT ASQINT STCINT
Bit Name Function
7CTS
Clear to Send.
0 = Wait before sending next command.
1 = Clear to send next command.
6ERR
Error.
0=Noerror
1 = Error
5:3 Reserved Values may vary.
2 RDSINT
RDS Interrupt.
0 = RDS interrupt has not been triggered.
1 = RDS interrupt has been triggered.
1ASQINT
Signal Quality Interrupt.
0 = Signal quality measurement has not been triggered.
1 = Signal quality measurement has been triggered.
0STCINT
Seek/Tune Complete Interrupt.
0 = Tune complete has not been triggered.
1 = Tune complete has been triggered.

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12 Rev. 0.8
5.1.1. Commands and Properties for the FM/RDS Transmitter
Command 0x01. POWER_UP
Initiates the boot process to move the device from powerdown to powerup mode. The boot can occur from internal
device memory or a system controller downloaded patch. To confirm that the patch is compatible with the internal
device library revision, the library revision should be confirmed by issuing the POWER_UP command with
Function = 15 (query library ID). The device will return the response, including the library revision, and then moves
into powerdown mode. The device can then be placed in powerup mode by issuing the POWER_UP command
with Function = 2 (transmit) and the patch may be applied. Only the STATUS byte will be returned in the response
stream in transmit mode. The POWER_UP command configures the state of DIN (pin 13), DFS (pin 14), and RIN
(pin 15) and LIN (pin 16) for analog or digital audio modes and GPO2/INT (pin 18) for interrupt operation. The
command configures GPO2/INT interrupts (GPO2OEN) and CTS interrupts (CTSIEN). If both are enabled,
GPO2/INT is driven high during normal operation and low for a minimum of 1 µs during the interrupt. The CTSIEN
bit is duplicated in the GPO_IEN property. The command is complete when the CTS bit (and optional interrupt) is
set.
Note: To change function (e.g., FM TX to FM RX), issue the POWER_DOWN command to stop the current function; then,
issue POWER_UP to start the new function.
Available in: All
Command Arguments: Two
Response Bytes: None (FUNC = 2), Seven (FUNC = 15)
Command
Bit D7D6D5D4D3D2D1D0
CMD 00000001
ARG1 CTSIEN GPO2OEN PATCH XOSCEN FUNC[3:0]
ARG2 OPMODE[7:0]
ARG Bit Name Function
1 7 CTSIEN
CTS Interrupt Enable.
0 = CTS interrupt disabled.
1 = CTS interrupt enabled.
1 6 GPO2OEN
GPO2 Output Enable.
0 = GPO2 output disabled, (Hi-Z).
1 = GPO2 output enabled.
15 PATCH
Patch Enable.
0 = Boot normally
1 = Copy non-volatile memory to RAM, but do not boot. After CTS has been set,
RAM may be patched
1 4 XOSCEN
Crystal Oscillator Enable.
0 = Use external RCLK (crystal oscillator disabled).
1 = Use crystal oscillator (RCLK and GPO3/DCLK with external 32.768 kHz crys-
tal and OPMODE=01010000).
See Si47xx Data Sheet Application Schematic for external BOM details.

AN332
Rev. 0.8 13
Response (to FUNC = 2, TX)
Response (to FUNC = 15, Query Library ID)
1 3:0 FUNC[3:0]
Function.
0–1, 3–14 = Reserved.
2 = Transmit.
15 = Query Library ID.
2 7:0 OPMODE[7:0]
Application Setting
01010000 = Analog audio inputs (LIN/RIN)
00001111 = Digital audio inputs (DIN/DFS/DCLK)
Bit D7D6D5 D4 D3 D2 D1 D0
STATUS CTS ERR X X X RDSINT ASQINT STCINT
Bit D7 D6 D5D4D3 D2 D1 D0
STATUS CTS ERR X X X RDSINT ASQINT STCINT
RESP1 PN[7:0]
RESP2 FWMAJOR[7:0]
RESP3 FWMINOR[7:0]
RESP4 RESERVED[7:0]
RESP5 RESERVED[7:0]
RESP6 CHIPREV[7:0]
RESP7 LIBRARYID[7:0]
RESP Bit Name Function
1 7:0 PN[7:0] Final 2 digits of part number.
2 7:0 FWMAJOR[7:0] Firmware Major Revision.
3 7:0 FWMINOR[7:0] Firmware Minor Revision.
4 7:0 RESERVED[7:0] Reserved, various values.
5 7:0 RESERVED[7:0] Reserved, various values.
6 7:0 CHIPREV[7:0] Chip Revision.
7 7:0 LIBRARYID[7:0] Library Revision.
ARG Bit Name Function

AN332
14 Rev. 0.8
Command 0x10. GET_REV
Returns the part number, chip revision, firmware revision, patch revision and component revision numbers. The
command is complete when the CTS bit (and optional interrupt) is set. This command may only be sent when in
powerup mode.
Available in: All
Command arguments: None
Response bytes: Eight
Command
Response
Bit D7D6D5 D4 D3 D2 D1 D0
CMD 000 1 0 0 0 0
Bit D7D6D5D4D3D2D1D0
STATUS CTS ERR X X X RDSINT ASQINT STCINT
RESP1 PN[7:0]
RESP2 FWMAJOR[7:0]
RESP3 FWMINOR[7:0]
RESP4 PATCHH[7:0]
RESP5 PATCHL[7:0]
RESP6 CMPMAJOR[7:0]
RESP7 CMPMINOR[7:0]
RESP8 CHIPREV[7:0]
RESP Bit Name Function
1 7:0 PN[7:0] Final 2 digits of Part Number
2 7:0 FWMAJOR[7:0] Firmware Major Revision
3 7:0 FWMINOR[7:0] Firmware Minor Revision
4 7:0 PATCHH[7:0] Patch ID High Byte
5 7:0 PATCHL[7:0] Patch ID Low Byte
6 7:0 CMPMAJOR[7:0] Component Major Revision
7 7:0 CMPMINOR[7:0] Component Minor Revision
8 7:0 CHIPREV[7:0] Chip Revision

AN332
Rev. 0.8 15
Command 0x11. POWER_DOWN
Moves the device from powerup to powerdown mode. The CTS bit (and optional interrupt) is set when it is safe to
send the next command. This command may only be sent when in powerup mode. Note that only the POWER_UP
command is accepted in powerdown mode. If the system controller writes a command other than POWER_UP
when in powerdown mode, the device does not respond. The device will only respond when a POWER_UP
command is written. GPO pins are powered down and not active during this state. For optimal power down
current, GPO2 must be either internally driven low through GPIO_CTL command or externally driven low.
Note: In FMTX component 1.0 and 2.0, a reset is required when the system controller writes a command other than
POWER_UP when in powerdown mode.
Note: The following describes the state of all the pins when in powerdown mode:
GPIO1, GPIO2, and GPIO3 = 0
DIN, DFS, RIN, LIN = HiZ
Available in: All
Command arguments: None
Response bytes: None
Command
Response
Bit D7 D6 D5 D4 D3 D2 D1 D0
CMD 000 1 0 0 0 1
Bit D7D6D5 D4 D3 D2 D1 D0
STATUS CTS ERR X X X RDSINT ASQINT STCINT

AN332
16 Rev. 0.8
Command 0x12. SET_PROPERTY
Sets a property shown in Table 5, “FM Transmitter Property Summary,” on page 8. The CTS bit (and optional
interrupt) is set when it is safe to send the next command. This command may only be sent when in powerup
mode.
See Figure 30, “CTS and SET_PROPERTY Command Complete tCOMP Timing Model,” on page 244 and
Table 48, “Command Timing Parameters for the FM Transmitter,” on page 245.
Available in: All
Command Arguments: Five
Response bytes: None
Command
Response
Bit D7D6D5D4D3D2D1D0
CMD 00010010
ARG1 00000000
ARG2 PROPH[7:0]
ARG3 PROPL[7:0]
ARG4 PROPDH[7:0]
ARG5 PROPDL[7:0]
ARG Bit Name Function
1 7:0 Reserved Always write to 0.
2 7:0 PROPH[7:0]
Property High Byte.
This byte in combination with PROPLis used to specify the property to
modify. See Section "5.1.2. FM/RDS Transmitter Properties" on page 31.
3 7:0 PROPL[7:0]
Property Low Byte.
This byte in combination with PROPHis used to specify the property to
modify. See Section "5.1.2. FM/RDS Transmitter Properties" on page 31.
4 7:0 PROPDH[7:0]
Property Value High Byte.
This byte in combination with PROPVLis used to set the property value.
See Section "5.1.2. FM/RDS Transmitter Properties" on page 31.
5 7:0 PROPDL[7:0]
Property Value Low Byte.
This byte in combination with PROPVHis used to set the property value.
See Section "5.1.2. FM/RDS Transmitter Properties" on page 31.
Bit D7D6D5 D4 D3 D2 D1 D0
STATUS CTS ERR X X X RDSINT ASQINT STCINT

AN332
Rev. 0.8 17
Command 0x13. GET_PROPERTY
Gets a property shown in Table 5, “FM Transmitter Property Summary,” on page 8. The CTS bit (and optional
interrupt) is set when it is safe to send the next command. This command may only be sent when in powerup
mode.
Available in: All
Command arguments: Three
Response bytes: Three
Command
Response
Bit D7D6D5D4D3D2D1D0
CMD 00010011
ARG1 00000000
ARG2 PROPH[7:0]
ARG3 PROPL[7:0]
ARG Bit Name Function
1 7:0 Reserved Always write to 0.
27:0 PROP
H[7:0] Property Get High Byte.
This byte in combination with PROPLis used to specify the property to get.
37:0 PROP
L[7:0] Property Get Low Byte.
This byte in combination with PROPHis used to specify the property to get.
BitD7D6D5D4D3D2D1D0
STATUS CTS ERR X X X RDSINT ASQINT STCINT
RESP1 XXXXXXXX
RESP2 PROPDH[7:0]
RESP3 PROPDL[7:0]
RESP Bit Name Function
1 7:0 Reserved Reserved, various values.
27:0PROPD
H[7:0]
Property Value High Byte.
This byte in combination with PROPVLwill represent the requested prop-
erty value.
37:0PROPD
L[7:0]
Property Value High Byte.
This byte in combination with PROPVHwill represent the requested prop-
erty value.

AN332
18 Rev. 0.8
Command 0x14. GET_INT_STATUS
Updates bits 6:0 of the status byte. This command should be called after any command that sets the STCINT,
ASQINT, or RDSINT bits. When polling this command should be periodically called to monitor the STATUS byte,
and when using interrupts, this command should be called after the interrupt is set to update the STATUS byte. The
command is complete when the CTS bit (and optional interrupt) is set. This command may only be sent when in
powerup mode.
Available in: All
Command arguments: None
Response bytes: None
Command
Response
Bit D7D6D5D4D3D2D1D0
CMD 00010100
BitD7D6D5D4D3D2D1D0
STATUS CTS ERR X X X RDSINT ASQINT STCINT

AN332
Rev. 0.8 19
Command 0x30. TX_TUNE_FREQ
Sets the state of the RF carrier and sets the tuning frequency between 76 and 108 MHz in 10 kHz units and steps
of 50 kHz. For example 76.05 MHz = 7605 is valid because it follows the 50 kHz step requirement but
76.01 MHz = 7601 is not valid. The CTS bit (and optional interrupt) is set when it is safe to send the next
command. The ERR bit (and optional interrupt) is set if an invalid argument is sent. Note that only a single interrupt
occurs if both the CTS and ERR bits are set. The optional STC interrupt is set when the command completes. The
STCINT bit is set only after the GET_INT_STATUS command is called. This command may only be sent when in
powerup mode. The command clears the STC bit if it is already set. See Figure 29, “CTS and STC Timing Model,”
on page 244 and Table 48, “Command Timing Parameters for the FM Transmitter,” on page 245.
Available in: All
Command arguments: Three
Response bytes: None
Command
Response
Bit D7D6D5D4D3D2D1D0
CMD 00110000
ARG1 00000000
ARG2 FREQH[7:0]
ARG3 FREQL[7:0]
ARG Bit Name Function
1 7:0 Reserved Always write to 0.
27:0FREQ
H[7:0]
Tune Frequency High Byte.
This byte in combination with FREQLselects the tune frequency in units of
10 kHz. The valid range is from 7600 to 10800 (76–108 MHz). The frequency
must be a multiple of 50 kHz.
37:0FREQ
L[7:0]
Tune Frequency Low Byte.
This byte in combination with FREQHselects the tune frequency in units of
10 kHz. The valid range is from 7600 to 10800 (76–108 MHz). The frequency
must be a multiple of 50 kHz.
Bit D7D6D5 D4 D3 D2 D1 D0
STATUS CTS ERR X X X RDSINT ASQINT STCINT

AN332
20 Rev. 0.8
Command 0x31. TX_TUNE_POWER
Sets the RF voltage level between 88 dBµV and 115 dBµV in 1 dB units. Power may be set as high as 120 dBµV;
however, voltage accuracy is not guaranteed. A value of 0x00 indicates off. The command also sets the antenna
tuning capacitance. A value of 0 indicates autotuning, and a value of 1–191 indicates a manual override. The CTS
bit (and optional interrupt) is set when it is safe to send the next command. The ERR bit (and optional interrupt) is
set if an invalid argument is sent. Note that only a single interrupt occurs if both the CTS and ERR bits are set. The
optional STC interrupt is set when the command completes. The STCINT bit is set only after the
GET_INT_STATUS command is called. This command may only be sent when in powerup mode. The command
clears the STC bit if it is already set. See Figure 29, “CTS and STC Timing Model,” on page 244 and Table 48,
“Command Timing Parameters for the FM Transmitter,” on page 245.
Available in: All
Command arguments: Four
Response bytes: None
Command
Response
Bit D7D6D5D4D3D2D1D0
CMD 00110001
ARG1 00000000
ARG2 00000000
ARG3 RFdBµV[7:0]
ARG4 ANTCAP[7:0]
ARG Bit Name Function
1 7:0 Reserved Always write to 0.
2 7:0 Reserved Always write to 0.
3 7:0 RFdBµV[7:0]
Tune Power Byte.
Sets the tune power in dBµV in 1 dB steps. The valid range is from 88–
115 dBµV. Power may be set as high as 120 dBµV; however, voltage accu-
racy is not guaranteed.
4 7:0 ANTCAP[7:0]
Antenna Tuning Capacitor.
This selects the value of the antenna tuning capacitor manually, or automati-
cally if set to zero. The valid range is 0 to 191, which results in a tuning
capacitance of 0.25 pF x ANTCAP.
Bit D7D6D5 D4 D3 D2 D1 D0
STATUS CTS ERR X X X RDSINT ASQINT STCINT