Mikroelektronika MIKROE-742 데이터 시트

The SPI module is available with a number of the AVR compliant MCUs. The mikroPascal PRO
for AVR provides a library (driver) for working with mikroElektronika's CANSPI Add-on boards
(with MCP2515 or MCP2510) via SPI interface.

The CAN is a very robust protocol that has error detection and signalization, self–checking and
fault confinement. Faulty CAN data and remote frames are re-transmitted automatically, similar
to the Ethernet.

Data transfer rates depend on distance. For example, 1 Mbit/s can be achieved at network
lengths below 40m while 250 Kbit/s can be achieved at network lengths below 250m. The greater
distance the lower maximum bitrate that can be achieved. The lowest bitrate defined by the stan-
dard is 200Kbit/s. Cables used are shielded twisted pairs.

CAN supports two message formats:

- Standard format, with 11 identifier bits and 
- Extended format, with 29 identifier bits 

- Consult the CAN standard about CAN bus termination resistance. 
- An effective CANSPI communication speed depends on SPI and certainly is slow

er than “real” CAN. 

- CANSPI module refers to mikroElektronika's CANSPI Add-on board connected to 

SPI module of MCU. 

- Prior to calling any of this library routines, Spi_Rd_Ptr needs to be initialized with 

the appropriate SPI_Read routine.

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- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 6

var CanSpi_CS : sbit; sfr;
external;

Chip Select line.

var CanSpi_CS : sbit at
PORTB.B0;

var CanSpi_Rst : sbit; sfr;
external;

Reset line.

var CanSpi_Rst : sbit at
PORTB.B2;

var CanSpi_CS_Bit_Direction :
sbit; sfr; external;

Direction of the Chip
Select pin.

var CanSpi_CS_Bit_Direction
: 

sbit at DDRB.B0;

var CanSpi_Rst_Bit_Direction
: 

Direction of the
Reset pin.

var CanSpi_Rst_Bit_Direction
: 

sbit at DDRB.B2;