Datasheet

© 2007-2012 Microchip Technology Inc. DS70292G-page 207
dsPIC33FJ32GP302/304, dsPIC33FJ64GPX02/X04, AND dsPIC33FJ128GPX02/X04
16.0 SERIAL PERIPHERAL
INTERFACE (SPI)
The Serial Peripheral Interface (SPI) module is a syn-
chronous serial interface useful for communicating with
other peripheral or microcontroller devices. These
peripheral devices can be serial EEPROMs, shift regis-
ters, display drivers, analog-to-digital converters, etc.
The SPI module is compatible with Motorola
®
SPI and
SIOP.
Each SPI module consists of a 16-bit shift register,
SPIxSR (where x = 1 or 2), used for shifting data in and
out, and a buffer register, SPIxBUF. A control register,
SPIxCON, configures the module. Additionally, a status
register, SPIxSTAT, indicates status conditions.
The serial interface consists of 4 pins:
• SDIx (serial data input)
• SDOx (serial data output)
• SCKx (shift clock input or output)
• SSx
(active-low slave select).
In Master mode operation, SCK is a clock output. In
Slave mode, it is a clock input.
FIGURE 16-1: SPI MODULE BLOCK DIAGRAM
Note 1: This data sheet summarizes the features
of the dsPIC33FJ32GP302/304,
dsPIC33FJ64GPX02/X04, and
dsPIC33FJ128GPX02/X04 families of
devices. It is not intended to be a compre-
hensive reference source. To comple-
ment the information in this data sheet,
refer to Section 18. “Serial Peripheral
Interface (SPI)” (DS70206) of the
“dsPIC33F/PIC24H Family Reference
Manual”, which is available from the
Microchip website (www.microchip.com).
2: Some registers and associated bits
described in this section may not be avail-
able on all devices. Refer to Section 4.0
“Memory Organization” in this data
sheet for device-specific register and bit
information.
Internal Data Bus
SDIx
SDOx
SSx
SCKx
SPIxSR
bit 0
Shift Control
Edge
Select
F
CY
Primary
1:1/4/16/64
Enable
Prescaler
Sync
SPIxBUF
Control
Transfer
Transfer
Write SPIxBUF
Read SPIxBUF
16
SPIxCON1<1:0>
SPIxCON1<4:2>
Master Clock
Clock
Control
Secondary
Prescaler
1:1 to 1:8
SPIxRXB SPIxTXB