Datasheet

 2007-2019 Microchip Technology Inc. DS30009905F-page 177
PIC24FJ256GA110 FAMILY
15.0 SERIAL PERIPHERAL
INTERFACE (SPI)
The Serial Peripheral Interface (SPI) module is a
synchronous serial interface useful for communicating
with other peripheral or microcontroller devices. These
peripheral devices may be serial EEPROMs, shift
registers, display drivers, A/D Converters, etc. The SPI
module is compatible with Motorola
®
SPI and SIOP
interfaces. All devices of the PIC24FJ256GA110 family
include three SPI modules.
The module supports operation in two buffer modes. In
Standard mode, data are shifted through a single serial
buffer. In Enhanced Buffer mode, data are shifted
through an 8-level FIFO buffer.
The module also supports a basic framed SPI protocol
while operating in either Master or Slave mode. A total
of four framed SPI configurations are supported.
The SPI serial interface consists of four pins:
• SDIx: Serial Data Input
• SDOx: Serial Data Output
• SCKx: Shift Clock Input or Output
• SSx: Active-Low Slave Select or Frame
Synchronization I/O Pulse
The SPI module can be configured to operate using
two, three or four pins. In the 3-pin mode, SSx
is not
used. In the 2-pin mode, both SDOx and SSx
are not
used.
Block diagrams of the module in Standard and
Enhanced modes are shown in Figure 15-1 and
Figure 15-2.
Note: This data sheet summarizes the features of
this group of PIC24F devices. It is not
intended to be a comprehensive reference
source. For more information, refer to
“Serial Peripheral Interface (SPI)”
(www.microchip.com/DS70005185) in
the “dsPIC33/PIC24 Family Reference
Manual”. The information in this data sheet
supersedes the information in the FRM.
Note: Do not perform Read-Modify-Write
(RMW) operations (such as bit-oriented
instructions) on the SPIxBUF register in
either Standard or Enhanced Buffer mode.
Note: In this section, the SPI modules are
referred to together as SPIx or separately
as SPI1, SPI2 or SPI3. Special Function
Registers will follow a similar notation. For
example, SPIxCON1 and SPIxCON2
refer to the control registers for any of the
three SPI modules.