CYRF69313_13 Datasheet, PDF (11/81 Pages) Cypress Semiconductor – Programmable Radio-on-Chip LPstar

CYRF69313
Figure 4. Three-Wire SPI Mode
MCU Function
Radio Function
P1.5/MOSI
MOSI
MOSI/MISO multiplexed
on one MOSI pin
P1.4/SCK
SCK
P1.3/nSS
nSS
Four-Wire SPI Interface
The four-wire SPI communications interface consists of MOSI,
MISO, SCK, and SS.
The device receives SCK from the MCU function on the SCK pin.
Data from the MCU function is shifted in on the MOSI pin. Data
to the MCU function is shifted out on the MISO pin. The active
low SS pin must be asserted for the two functions to
communicate. The IRQ function may be optionally multiplexed
with the MOSI pin; when this option is enabled the IRQ function
is not available while the SS pin is low. When using this
configuration, user firmware should ensure that the MOSI
function on MCU function is in a high impedance state whenever
SS is high.
Figure 5. Four-Wire SPI Mode
MCU Function
P1.6/MISO
P1.5/MOSI
P1.4/SCK
Radio Function
MOSI
SCK
MISO
SPI Communication and Transactions
The SPI transactions can be single byte or multi-byte. The MCU
function initiates a data transfer through a Command/Address
byte. The following bytes are data bytes. The SPI transaction
format is shown in Table 2 on page 12.
The DIR bit specifies the direction of data transfer. 0 = Master
reads from slave. 1 = Master writes to slave.
The INC bit helps to read or write consecutive bytes from
contiguous memory locations in a single burst mode operation.
If Slave Select is asserted and INC = 1, then the master MCU
function reads a byte from the radio, the address is incremented
by a byte location, and then the byte at that location is read, and
so on. If Slave Select is asserted and INC = 0, then the MCU
function reads/writes the bytes in the same register in burst
mode, but if it is a register file then it reads/writes the bytes in
that register file.
The SPI interface between the radio function and the MCU is not
dependent on the internal 12 MHz oscillator of the radio.
Therefore, radio function registers can be read from or written
into while the radio is in sleep mode.
SPI I/O Voltage References
The SPI interfaces between MCU function and the radio and the
IRQ and RST have a separate voltage reference V_IO, enabling
the radio function to directly interface with the MCU function,
which operates at higher supply voltage. The internal SPIO pins
between the MCU function and radio function should be
connected with a regulated voltage of 3.3 V (by setting [bit4] of
Registers P13CR, P14CR, P15CR, and P16CR of the MCU
function) and the internal 3.3 V regulator of the MCU function
should be turned on.
SPI Connects to External Devices
The three SPI wires, MOSI, SCK, and SS are also drawn out of
the package as external pins to allow the user to interface their
own external devices (such as optical sensors and others)
through SPI. The radio function also has its own SPI wires MISO
and IRQ, which can be used to send data back to the MCU
function or send an interrupt request to the MCU function. They
can also be configured as GPIO pins.
P1.3/nSS
nSS
This connection is external to the PRoC LPstar Chip
Document Number: 001-66503 Rev. *D
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