DSPIC33FJ64GP306 Microchip Technology Inc., DSPIC33FJ64GP306 Datasheet - Page 163

• Manufacturer Part Number: DSPIC33FJ64GP306
• Description: High-performance, 16-bit Digital Signal Controllers
• Manufacturer: Microchip Technology Inc.

15.0
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, ADC, etc. The SPI module is
compatible with SPI and SIOP from Motorola
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 various status conditions.
The serial interface consists of 4 pins: SDIx (serial data
input), SDOx (serial data output), SCKx (shift clock input
or output), and SSx (active low slave select).
In Master mode operation, SCK is a clock output but in
Slave mode, it is a clock input.
A series of eight (8) or sixteen (16) clock pulses shift out
bits from the SPIxSR to SDOx pin and simultaneously
shift in data from SDIx pin. An interrupt is generated
when the transfer is complete and the corresponding
interrupt flag bit (SPI1IF or SPI2IF) is set. This interrupt
can be disabled through an interrupt enable bit (SPI1IE
or SPI2IE).
The receive operation is double-buffered. When a com-
plete byte is received, it is transferred from SPIxSR to
SPIxBUF.
If the receive buffer is full when new data is being trans-
ferred from SPIxSR to SPIxBUF, the module will set the
SPIROV bit indicating an overflow condition. The transfer
of the data from SPIxSR to SPIxBUF will not be com-
pleted and the new data will be lost. The module will not
respond to SCL transitions while SPIROV is ‘1’, effec-
tively disabling the module until SPIxBUF is read by user
software.
Transmit writes are also double-buffered. The user writes
to SPIxBUF. When the master or slave transfer is com-
pleted, the contents of the shift register (SPIxSR) are
© 2007 Microchip Technology Inc.
Note:
Note:
SERIAL PERIPHERAL
INTERFACE (SPI)
This data sheet summarizes the features
of this group of dsPIC33FJXXXGPX06/
X08/X10 devices. It is not intended to be a
comprehensive reference source.
complement the information in this data
sheet, refer to the “dsPIC33F Family
Reference Manual” . Please refer to the
Microchip web site (www.microchip.com)
for the latest dsPIC33F Family Reference
Manual sections.
In this section, the SPI modules are
referred to together as SPIx, or separately
as SPI1 and SPI2. Special Function Reg-
isters will follow a similar notation. For
example, SPIxCON refers to the control
register for the SPI1 or SPI2 module.
dsPIC33FJXXXGPX06/X08/X10
®
.
To
moved to the receive buffer. If any transmit data has been
written to the buffer register, the contents of the transmit
buffer are moved to SPIxSR. The received data is thus
placed in SPIxBUF and the transmit data in SPIxSR is
ready for the next transfer.
To set up the SPI module for the Master mode of
operation:
1.
2.
3.
4.
5.
To set up the SPI module for the Slave mode of operation:
1.
2.
3.
4.
5.
6.
7.
Note:
If using interrupts:
a)
b)
c)
Write the desired settings to the SPIxCON
register with MSTEN (SPIxCON1<5>) = 1.
Clear the SPIROV bit (SPIxSTAT<6>).
Enable SPI operation by setting the SPIEN bit
(SPIxSTAT<15>).
Write the data to be transmitted to the SPIxBUF
register. Transmission (and reception) will start as
soon as data is written to the SPIxBUF register.
Clear the SPIxBUF register.
If using interrupts:
a)
b)
c)
Write the desired settings to the SPIxCON1 and
SPIxCON2
(SPIxCON1<5>) = 0.
Clear the SMP bit.
If the CKE bit is set, then the SSEN bit
(SPIxCON1<7>) must be set to enable the SSx
pin.
Clear the SPIROV bit (SPIxSTAT<6>).
Enable SPI operation by setting the SPIEN bit
(SPIxSTAT<15>).
Clear the SPIxIF bit in the respective IFSn
register.
Set the SPIxIE bit in the respective IECn
register.
Write the SPIxIP bits in the respective IPCn
register to set the interrupt priority.
Clear the SPIxIF bit in the respective IFSn
register.
Set the SPIxIE bit in the respective IECn
register.
Write the SPIxIP bits in the respective IPCn
register to set the interrupt priority.
Both the transmit buffer (SPIxTXB) and
the receive buffer (SPIxRXB) are mapped
to the same register address, SPIxBUF.
Do not perform read-modify-write opera-
tions (such as bit-oriented instructions) on
the SPIxBUF register.
registers
with
DS70286A-page 161
MSTEN