RXM0SIDL datasheet(3/92 Pages) MICROCHIP

3 / 92 page

 2003-2012 Microchip Technology Inc.

DS21801G-page 3

MCP2515

1.0

DEVICE OVERVIEW

The MCP2515 is a stand-alone CAN controller

developed

simplify

applications

that

require

interfacing with a CAN bus. A simple block diagram of

the MCP2515 is shown in Figure 1-1. The device

consists of three main blocks:

The CAN module, which includes the CAN

protocol engine, masks, filters, transmit and

receive buffers.

The control logic and registers that are used to

configure the device and its operation.

The SPI protocol block.

An example system implementation using the device is

shown in Figure 1-2.

1.1

CAN Module

The CAN module handles all functions for receiving

and transmitting messages on the CAN bus. Messages

are transmitted by first loading the appropriate

message buffer and control registers. Transmission is

initiated by using control register bits via the SPI

interface or by using the transmit enable pins. Status

and errors can be checked by reading the appropriate

registers. Any message detected on the CAN bus is

checked for errors and then matched against the user-

defined filters to see if it should be moved into one of

the two receive buffers.

1.2

Control Logic

The control logic block controls the setup and operation

of the MCP2515 by interfacing to the other blocks in

order to pass information and control.

Interrupt pins are provided to allow greater system

flexibility. There is one multi-purpose interrupt pin (as

well as specific interrupt pins) for each of the receive

registers that can be used to indicate a valid message

has been received and loaded into one of the receive

buffers. Use of the specific interrupt pins is optional.

The general purpose interrupt pin, as well as status

registers (accessed via the SPI interface), can also be

used to determine when a valid message has been

received.

Additionally, there are three pins available to initiate

immediate transmission of a message that has been

loaded into one of the three transmit registers. Use of

these

pins

optional,

initiating

message

transmissions can also be accomplished by utilizing

control registers, accessed via the SPI interface.

1.3

SPI Protocol Block

The MCU interfaces to the device via the SPI interface.

Writing

to,

and

reading

from,

all

registers

accomplished using standard SPI read and write

commands, in addition to specialized SPI commands.

FIGURE 1-1:

BLOCK DIAGRAM

SPI

Interface

Logic

SPI

Bus

INT

SCK

CAN

Protocol

Engine

RXCAN

TXCAN

Control Logic

RX0BF

RX1BF

TX0RTS

TX1RTS

TX2RTS

TX and RX Buffers

Masks and Filters

CAN Module

RESET

Timing

Generation

OSC1

OSC2

CLKOUT

Control

and

Interrupt

Registers

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