SI3230PPQX-EVB Silicon Laboratories Inc, SI3230PPQX-EVB Datasheet - Page 37

• Manufacturer Part Number: SI3230PPQX-EVB
• Description: BOARD EVAL W/DISCRETE INTERFACE
• Manufacturer: Silicon Laboratories Inc
• Series: ProSLIC®r

Specifications of SI3230PPQX-EVB

• Main Purpose: Interface, Analog Front End (AFE)
• Utilized Ic / Part: Si3230
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

2.10. Serial Peripheral Interface
The control interface to the ProSLIC is a 4-wire interface
modeled after commonly available micro-controller and
serial peripheral devices. The interface consists of a
clock (SCLK), chip select (CS), serial data input (SDI),
and serial data output (SDO). Data is transferred a byte
at a time with each register access consisting of a pair
of byte transfers. Figures 17 and 18 illustrate read and
write operation in the SPI bus.
The first byte of the pair is the command/address byte.
The MSB of this byte indicates register read when 1 and
a register write when 0. The remaining seven bits of the
command/address byte indicate the address of the
register to be accessed. The second byte of the pair is
the data byte. Because the falling edge of CS provides
resynchronization of the SPI state machine in the event
of a framing error, it is recommended (but not required)
that CS be taken high between byte transfers as shown
in Figures 17 and 18. During a read operation, the SDO
becomes active and the 8-bit contents of the register
are driven out MSB first. The SDO will be high
impedence on either the falling edge of SCLK following
the LSB, or the rising of CS as specified by the SPIM bit
(direct Register 0, bit 6). SDI is a “don’t care” during the
data portion of read operations. During write operations,
data is driven into the ProSLIC via the SDI pin MSB first.
The SDO pin will remain high impedance during write
operations. Data always transitions with the falling edge
of the clock and is latched on the rising edge. The clock
should return to a logic high when no transfer is in
progress.
SCLK
SDO
SDI
CS
0
a6
a5
a4
Figure 17. Serial Write 8-Bit Mode
a3
a2
Preliminary Rev. 0.96
a1
a0
High Impedance
Indirect registers are accessed through direct registers
29 through 30. Instructions on how to access them is
described in “3. Control Registers”
page 40.
There are a number of variations of usage on this four-
wire interface:
Don't
Care
Continuous clocking. During continuous clocking,
the data transfers are controlled by the assertion of
the CS pin. CS must assert before the falling edge of
SCLK on which the first bit of data is expected during
a read cycle, and must remain low for the duration of
the 8-‘bit transfer (command/address or data).
SDI/SDO wired operation. Independent of the
clocking options described, SDI and SDO can be
treated as two separate lines or wired together if the
master is capable of tristating its output during the
data byte transfer of a read operation.
Daisy chain mode. This mode allows
communication with banks of up to eight ProSLIC
devices using one chip select signal. When the
SPIDC bit in the SPI Mode Select register is set,
data transfer mode changes to a 3-byte operation: a
chip select byte, an address/control byte, and a data
byte. Using the circuit shown in Figure 19, a single
device may select from the bank of devices by
setting the appropriate chip select bit to 1. Each
device uses the LSB of the chip select byte, shifts
the data right by one bit, and passes the chip select
byte using the SDITHRU pin to the next device in the
chain. Address/control and data bytes are unaltered.
d7
d6
d5
d4
d3
d2
d1
Si3230
d0
beginning on
37