AN349: Si4708/09 Programming Guide

AN349
Si4708/09 P ROGRAMMING G U I D E
1. Introduction
1.1. Scope
This document applies to Si4708/09 and example code version 0.1 and greater. Refer to www.mysilabs.com for
example code.
1.2. Purpose
This document is intended to be used with Silicon Laboratories “AN230: Si4700/01/02/03 Programming Guide."
The purpose of this programming guide is to describe features that are unique to the Si4708/09:

Device initialization sequence and busmode selection
Powerup and powerdown sequences
 Hardware control registers
For topics that are not covered in this document, refer to AN230.

This document references the Si4708/09 data sheet and AN230.
1.3. Terminology
SENB or SEN—serial enable pin, active low, used only for 3-wire operation.
SDIO—serial data in/data out pin.
SCLK—serial clock pin.
RSTB or RST—reset pin, active low.
Device—refers to the Si4708/09.
1.4. Differences between Si4708/09 and Si4700/01/02/03
The Si4708/09 uses a 2.5x2.5 mm 16-pin QFN package. The Si4702/03 and Si4700/01 use 20-pin and 24-pin
packages, respectively. For the purpose of programming, the key difference is that the Si4708/09 does not have
GPIO1 and GPIO3 pins, and, as a result, the Si4708/09 does not offer an internal oscillator function and only offers
bus mode selection with the SENB pin. This necessitates minor differences in the initialization sequence, busmode
selection, powerup and powerdown sequences, and hardware control registers for the Si4708/09. Key differences
between the Si4708/09 and the Si4700/01/02/03 are presented in bold text.
Rev. 0.1 7/08
Copyright © 2008 by Silicon Laboratories
AN349
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TABLE O F C ONTENTS
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.2. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.4. Differences between Si4708/09 and Si4700/01/02/03 . . . . . . . . . . . . . . . . . . . . . . . .1
2. Hardware Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2.1. Power, Initialization Sequence, and Busmode Selection . . . . . . . . . . . . . . . . . . . . . .4
2.2. 2-Wire Control Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3. Software Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.1. Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.2. Hardware Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
3.3. General Configuration Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.4. Regional Configuration Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.5. End User Adjustable Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.6. Seek Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.7. Tune Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.8. RDS/RBDS (Si4709 Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4. Programming with Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5. Command and Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Appendix—Seek Adjustability and Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
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2. Hardware Description
2.1. Power, Initialization Sequence, and Busmode Selection
VA,VD Supply
VIO Supply
RST Pin
RCLK Pin
ENABLE Bit
1
2
3
4
5
Figure 1. Initialization Sequence
2.1.1. Hardware Initialization
The FM tuner device is capable of communicating using either a 3-wire or 2-wire interface. The selection of this
interface is made during the reset sequence.
Figure 1 demonstrates the sequencing of hardware events relative to reset. Figure 2 combines this information
with the setting of the ENABLE and DISABLE bits to better describe the possible combinations. The following steps
should be used to initialize the device properly.
1. Supply VA and VD.
2. Supply VIO while keeping the RST pin low. Note that power supplies may be sequenced in any order (steps 1
and 2 may be reversed).
3. Configure the SENB pin for bus mode selection. See Figure 3, “Powerup, Powerdown, and Reset Flowchart,”
on page 6.
4. Set the RST pin high. The device registers may now be read and written.
5. Provide RCLK. A delay may be necessary for some external oscillator circuits to ensure that the
oscillator has stabilized. Please determine the necessary stabilization time for the clock source in the
system.
Note: The Si4708/09 does not offer an internal oscillator option.
6. Set the ENABLE bit high and the DISABLE bit low to power up the device.
2.1.2. Hardware Powerdown
A powerdown mode is available to reduce power consumption when the part is idle. Setting both the ENABLE bit
high and the DISABLE bit high starts the powerdown sequence. This disables analog and digital circuitry while
maintaining register configuration and keeping the bus active. Note that the device automatically sets the ENABLE
bit low after the internal powerdown sequence completes. Setting the ENABLE bit low directly will cause the device
to partially powerdown and should be avoided. See Figure 2. Setting the ENABLE bit high and the DISABLE bit low
will bring the device out of powerdown mode and resume normal operation. Refer to Figure 1 for more information.
To power down the device:
1. Set Register 4 [5:4], [3:2], and [1:0] to 0b10. This step is required for the Si4708/09 to ensure VIO
powerdown mode current meets data sheet specifications.
2. Set the ENABLE bit high and the DISABLE bit high to place the device in powerdown mode. Note that all
register states are maintained so long as VIO is supplied and the RST pin is high.
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3. Remove VA and VD supplies as needed.
To power up the device (after power down):
Note: VIO is still supplied in this scenario. If VIO is not supplied, refer to 2.1.1. "Hardware Initialization”
1. Supply VA and VD.
2. Set the ENABLE bit high and the DISABLE bit low to powerup the device.
Setting the RST pin low will disable analog and digital circuitry, reset the registers to their default settings, and
disable the bus. Setting the RST pin high will bring the device out of reset, place the device in powerdown mode,
and latch which bus mode will be used to communicate with the device. The bus mode selection is determined by
the SENB pin. To select 2-wire operation, the SENB pin must be sampled high by the device on the rising edge of
RST. To select 3-wire operation, the SENB pin must be sampled low by the device on the rising edge of RST (See
Figure 3). Please refer to the data sheet for more information regarding bus selection and timing requirements of
the RST signal.
More details on the register access during powerup and powerdown can be found in Section "3.2.1.ENABLE
(02h.0)/DISABLE (02h.6)—Powerup Control" on page 8.
Low power,
Inactive
Device Status
Power Supply Status
VA Optional
VD Optional
VIO Optional
RCLK Optional
VIO must be supplied prior to the
rising edge of reset
Inactive
Registers reset to
default values
Bus Inactive
Undesirable,
Do Not Use
Normal
Operation
Low power,
Bus Accessible
RST = GND
RST = VIO
VA Optional
VD Optional
VIO Required
RCLK Optional
VA, VD, and RCLK must be supplied
prior to writing ENABLE = 1
Powerdown
Write:
ENABLE = 1
DISABLE = 1
Read:
ENABLE = 0
DISABLE = 0
Write:
ENABLE = 1
DISABLE = 0
Powerup
Write:
ENABLE = 1
DISABLE = 0
Read:
ENABLE = 1
DISABLE = 0
Partial
Powerdown
Write:
ENABLE = 0
DISABLE = X
Read:
ENABLE = 0
DISABLE = X
VA Required
VD Required
VIO Required
RCLK Required
VA Optional
VD Optional
VIO Required
RCLK Optional
Note: See data sheet for further details.
Figure 2. Powerup, Powerdown, and Reset State Diagram
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Inactive
No
RST = VIO?
Bus Mode Select
Yes
No
No
SENb = VIO?
SENb = GND?
Invalid Option
Yes
Yes
Control
Interface =
3-wire
mode
Control
Interface =
2-wire
mode
Powerdown
Control Interface
activated
Note: See data sheet for further details.
Figure 3. Powerup, Powerdown, and Reset Flowchart
2.1.3. Wire Control Interface
For information on the 3-wire control interface, refer to Section 2.2 of “AN230: Si4700/01/02/03 Programming
Guide."
2.2. 2-Wire Control Interface
For information on the 2-wire control interface, refer to Section 2.2 of “AN230: Si4700/01/02/03 Programming
Guide."
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3. Software Configuration
3.1. Registers
The control and status of the device is obtained through bitfields within 16 registers of 16 bits each. The
functionality of the bits can be separated into two main categories: control and status. The control bits can be
further subdivided into categories of when or how they are used (see Table 1). While the status bits can be
classified as static, static after power up, or dynamic after power up (see Table 2). Note that the Si4708/09 does
not offer GPIO1 or GPIO3.
Table 1. Register Use
Bit(s)
Hardware Control
DISABLE
X
ENABLE
X
AHIZEN
X
GPO
X
RDSIEN
X
STCIEN
X
General
Config
BLNDADJ
X
DSMUTE
X
SMUTER
X
SMUTEA
X
VOLEXT
X
SEEKTH
X
SKSNR
X
SKCNT
X
RDSPRF
X
RDSM
X
Regional
Config
RDS
X
DE
X
BAND
X
SPACE
X
End User
Adjustable
DMUTE
X
MONO
X
VOLUME
X
Seek
SEEKUP
X
SKMODE
X
SEEK
X
Tune
TUNE
X
CHAN
X
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Table 2. Status Bit Classification
Bit(s)
Static
PN
X
MFGID
X
Static After Power Up
REV
X
DEV
X
FIRMWARE
X
Dynamic After Power Up
ST
X
RSSI
X
READCHAN
X
STC
X
SF/BL
X
AFCRL
X
RDSR
X
RDSS
X
BLERA
X
BLERB
X
BLERC
X
BLERD
X
RDSA
X
RDSB
X
RDSC
X
RDSD
X
3.2. Hardware Control Registers
The following set of registers alter the hardware in some way. These registers are typically the first group to be
programmed.
3.2.1. ENABLE (02h.0)/DISABLE (02h.6)—Powerup Control
The ENABLE/DISABLE bits are analogous to the on/off buttons of the device. ENABLE=1 turns the device on while
DISABLE=1 turns the device off (powerdown mode). When writing the register to place the device into powerdown
mode, ENABLE should remain set to 1 while setting DISABLE to 1. The device clears the ENABLE and DISABLE
bits, indicating the powerdown mode has been entered.
Table 3 shows the sequence of commands required to powerup the device. Note that address 07h may be written
during powerup configuration.
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Table 3. Powerup Configuration Sequence
Write address 02h (required).
 Set the DMUTE bit to disable mute. Optionally mute can be disabled later when audio is needed.
 Set the ENABLE bit high to set the powerup state.
 Set the DISABLE bit low to set the powerup state.
Example: Write data 4001h.
Wait for device powerup (required).
 Refer to the Powerup Time specification in Table 7 "FM Characteristics" of the data sheet.
Read addresses 00h–01h (optional).
 The bits PN[3:0] = 1 indicate the part family: Si4708/09.
 The bits MFGID[11:0] = 242h indicate Silicon Laboratories as the manufacturer.
 The bits REV[5:0] = 1 indicates silicon revision B.
 The bits DEV indicate the identity of the device:
DEV = 0010 after powerup = Si4708.
DEV = 1010 after powerup = Si4709.
 The FIRMWARE bits indicate the firmware revision after powerup.
Read addresses 02h-0Fh (optional)
 Storing the values of each of the 16 registers locally is recommended to simplify manipulation of register bits
and to reduce the number of reads/writes to the I/O bus. These are referred to as the shadow registers and can
be stored in a 16 word array, shadow_reg[].
Example: To write bit 15 of register 07h after power up, write 07h as shadow_reg[0x07] ^ 0x8000
Write remaining hardware configuration registers (required).
Write the general configuration registers (required).
Write the regional configuration registers (required).
These registers can be programmed in any order.
See Powerup Time in data sheet
Optional
WR02
RD01
ENABLE = 1
DISABLE = 0
RD02-0F
Required
DEV = ?
Figure 4. Powerup Timing
Table 4 shows the sequence of commands required to powerdown the device. The tuner can optionally be
programmed to place the audio output pins into a high impedance state. If this is desired, set the AHIZEN bit in
register 07h prior to setting the disable bit. See AN230, Section "3.2.3.AHIZEN (07h.14)—Audio High-Z Enable" on
page 10 for more information. Set Register 4 [5:4] and [1:0] to 10b prior to setting the disable bit.
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Table 4. Powerdown Sequence
Write address 07h (optional for LOUT and ROUT Hi-Z).
 Set AHIZEN. All other bits in this register should be maintained at the value last read (i.e., 0x3C04 or 0xBC04).
Example: Write data 7C04h.
Write address 04h (This step is required for the Si4708/09 to reduce powerdown mode current).
 Set Register 4 [5:4] and [1:0] to 10b. All other bits in this register should be maintained at the value last
read.
Example: Write data 002Ah.
Write address 02h (required).
 Clear the DMUTE bit to enable mute.
 Set the ENABLE bit high and DISABLE bit high to set the powerdown state.
 After the DISABLE bit is set high, the device performs an internal powerdown sequence and then sets the
ENABLE and DISABLE bits low. Setting the ENABLE bit directly to 0 will cause the device to partially
powerdown.
Example: Write data 0041h.
1.5 ms max
WR02
RD02
ENABLE = 1
DISABLE = 1
Optional
Required
ENABLE = 0
DISABLE = 0
Figure 5. Powerdown Timing
3.2.2. XOSCEN-Crystal Oscillator Enable (Not available on Si4708/09)
The internal oscillator is not available on the Si4708/09. The Si4708/09-B requires a 32.768 kHz reference clock to
the RCLK pin. Refer to the Si4708/09 datasheet for more information.
3.2.3. AHIZEN (07h.14)—Audio High-Z Enable
For information on audio high-Z enable, refer to Section 3.2.3 of “AN230: Si4700/01/02/03 Programming Guide."
3.2.4. GPIO1-General Purpose I/O 1 (Not available on Si4708/09)
General purpose I/O 1 is not available on the Si4708/09.
3.2.5. GPO (04h.3:2)/RDSIEN (04h.15)/STCIEN (04h.14)—General Purpose I/O, Interrupts
GPO can be programmed to four different states as shown in Table 5. When programmed as an interrupt, the
device will generate interrupts based on the settings of RDSIEN and STCIEN. If RDSIEN is set a 5 ms interrupt
pulse will be generated when RDS data is available. If STCIEN is set a 5 ms interrupt pulse will be generated upon
completion of a SEEK or TUNE command. If both interrupts are enabled, the first interrupt after a SEEK or TUNE
will be the STC interrupt. Subsequent interrupts will be RDS interrupts. This pin can also be used as a general
purpose output or left unused. RDS is only available on the Si4709.
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Table 5. GPO States
00
High impedance (default)
01
STC/RDS interrupt
10
Low output (GND level)
11
High output (VIO level)
3.2.6. GPIO3-General Purpose I/O 3 (Not available on Si4708/09)
General purpose I/O 3 is not available on the Si4708/09.
3.3. General Configuration Control Registers
For information on general configuration control registers, refer to Section 3.3 of “AN230: Si4700/01/02/03
Programming Guide."
3.4. Regional Configuration Control Registers
For information on regional configuration control registers, refer to Section 3.4 of “AN230: Si4700/01/02/03
Programming Guide."
3.5. End User Adjustable Control Registers
For information on end user adjustable control registers, refer to Section 3.5 of “AN230: Si4700/01/02/03
Programming Guide."
3.6. Seek Control Registers
For information on seek control registers, refer to Section 3.6 of “AN230: Si4700/01/02/03 Programming Guide."
3.7. Tune Control Registers
For information on tune control registers, refer to Section 3.7 of “AN230: Si4700/01/02/03 Programming Guide."
3.8. RDS/RBDS (Si4709 Only)
For information on RDS/RBDS, refer to Section 3.8 of “AN230: Si4700/01/02/03 Programming Guide." Note this
section applies to the Si4709 in addition to the Si4701/03.
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4. Programming with Commands
For information on programming with commands, refer to Section 4 of AN230 "Si4700/01/02/03 Programming
Guide." Note this section applies to the Si4708/09 in addition to the Si4702/03 Rev C.
5. Command and Properties
For information on command and properties, refer to Section 5 of AN230 "Si4700/01/02/03 Programming Guide."
Note this section applies to the Si4708/09 in addition to the Si4702/03 Rev C.
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A PPENDIX — S EEK A DJUSTABILITY A N D S ETTINGS
For information on seek adjustability and settings, refer to the Appendix in “AN230: Si4700/01/02/03 Programming
Guide."
Rev. 0.1
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