SI4706-D50 Datasheet, PDF (26/36 Pages) Silicon Laboratories – HIGH-PERFORMANCE FM AND RDS/RBDS RECEIVER

Si4706-D50
4.15.2. 3-Wire Control Interface Mode
When selecting 3-wire mode, the user must ensure that
a rising edge of SCLK does not occur within 300 ns
before the rising edge of RST.
The 3-wire bus mode uses the SCLK, SDIO, and SEN_
pins. A transaction begins when the user drives SEN
low. Next, the user drives a 9-bit control word on SDIO,
which is captured by the device on rising edges of
SCLK. The control word consists of a 3-bit device
address (A7:A5 = 101b), a read/write bit (read = 1, write
= 0), and a 5-bit register address (A4:A0).
For write operations, the control word is followed by a
16-bit data word, which is captured by the device on
rising edges of SCLK.
For read operations, the control word is followed by a
delay of one-half SCLK cycle for bus turn-around. Next,
the Si4706 will drive the 16-bit read data word serially
on SDIO, changing the state of SDIO on each rising
edge of SCLK.
A transaction ends when the user sets SEN high, then
pulses SCLK high and low one final time. SCLK may
either stop or continue to toggle while SEN is high.
In 3-wire mode, commands are sent by first writing each
argument to register(s) 0xA1–0xA3, then writing the
command word to register 0xA0. A response is
retrieved by reading registers 0xA8–0xAF.
For details on timing specifications and diagrams, refer
to Table 6, “3-Wire Control Interface Characteristics” on
page 9; Figure 4, “3-Wire Control Interface Write Timing
Parameters,” on page 9, and Figure 5, “3-Wire Control
Interface Read Timing Parameters,” on page 9.
4.16. GPO Outputs
The Si4706 provides three general-purpose output pins.
The GPO pins can be configured to output a constant
low, constant high, or high-Z. The GPO pins are
multiplexed with the bus mode pins or DCLK,
depending on the application schematic of the device.
GPO2/INT can be configured to provide interrupts for
seek and tune complete, receive signal quality, and
RDS.
4.17. Reset, Powerup, and Powerdown
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. A powerdown mode is available to
reduce power consumption when the part is idle. Putting
the device in powerdown mode will disable analog and
digital circuitry while keeping the bus active.
4.18. Programming with Commands
To ease development time and offer maximum
customization, the Si4706 provides a simple yet
powerful software interface to program the receiver. The
device is programmed using commands, arguments,
properties, and responses. To perform an action, the
user writes a command byte and associated arguments,
causing the chip to execute the given command.
Commands control an action such as powerup the
device, shut down the device, or tune to a station.
Arguments are specific to a given command and are
used to modify the command. A complete list of
commands is available in “AN332: Si47xx Programming
Guide”.
Properties are a special command argument used to
modify the default chip operation and are generally
configured immediately after powerup. Examples of
properties are de-emphasis level, RSSI seek threshold,
and soft mute attenuation threshold. Responses provide
the user information and are echoed after a command
and associated arguments are issued. All commands
provide a one-byte status update indicating interrupt
and clear-to-send status information. For a detailed
description of the commands and properties for the
Si4706, see “AN332: Si47xx Programming Guide”.
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