Microchip Technology dsPIC33F Family Manual de usuario descargar pdf (Pagina 31)

dsPIC33F

Figure 8-4 is a block diagram of the DCI module. The

DCI can support up to 16 time slots in a data frame for

a maximum frame size of 256 bits. There are control

bits for each time slot in the data frame that determine

whether the DCI will transmit/receive during the time

slot. The DCI module supports DMA data transfers.

FIGURE 8-4: DCI MODULE BLOCK DIAGRAM

8.8 SPI™ Module

The Serial Peripheral Interface (SPI) module is a

synchronous serial interface for communicating with

other peripheral or microcontroller devices such as

serial EEPROMs, shift registers, display drivers, A/D

Converters, etc. It is compatible with Motorola

SPI and

SIOP interfaces.

This SPI module includes all SPI modes. A Frame

Synchronization mode is also included for support of

voice band codecs.

Four pins make up the serial interface: SDI, Serial Data

Input; SDO, Serial Data Output; SCK, Shift Clock Input

or Output; SS

, Active-Low Slave Select, which also

serves as the FSYNC (Frame Synchronization Pulse).

A device set up as an SPI master provides the serial

communication clock signal on its SCK pin.

A series of 8 or 16 clock pulses (depending on mode)

shift out the 8 or 16 bits (depending on whether a byte

or word is being transferred) and simultaneously shift in

8 or 16 bits of data from the SDI pin. An interrupt is

generated when the transfer is complete.

Slave select synchronization allows selective enabling

of SPI slave devices, which is particularly useful when

a single master is connected to multiple slaves.

The SPI1 and SPI2 modules support DMA data

transfers.

BCG Control Bits

16-Bit Data Bus

Sample Rate

Generator

CSCKD

COFSD

DCI Buffer

Frame

Synchronization

Generator

Control Unit

DCI Shift Register

Receive Buffer

Registers w/Shadow

FOSC/4

Word Size Selection bits

Frame Length Selection bits

DCI Mode Selection bits

CSCK

COFS

CSDI

CSDO

Transmit Buffer

Registers w/Shadow

1 2 ... 26 27 28 29 30 31 32 33 34 35 36 ... 89 90

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