Spi.h File Reference

Spi.h declares SPI hardware types and variables common to the SPI Master and SPI Slave. More...

#include <stdint.h>
#include "ReadWriteBits.h"

Go to the source code of this file.

Typedefs
typedef uint8_t volatile *const	spi_reg
typedef uint8_t const	spi_bit

Functions
void	_EnableSpiModule (void)
bool	_SpiTransferIsDone (void)
uint8_t	ReadSpiStatusRegister (void)
uint8_t	ReadSpiDataRegister (void)
void	ClearSpiInterruptFlag (void)

Variables
spi_reg	Spi_PortDirection
	Atmel DDR.
spi_reg	Spi_PortInput
	Atmel PIN.
spi_reg	Spi_PortOutput
	Atmel PORT.
spi_reg	Spi_PortPullup
	Atmel PORT alias.
spi_reg	Spi_SPCR
	SPI Control Register.
spi_reg	Spi_SPSR
	SPI Status Register.
spi_reg	Spi_SPDR
	SPI Data Register. More...
spi_bit	Spi_DataReady
spi_bit	Spi_Ss
spi_bit	Spi_Mosi
spi_bit	Spi_Miso
spi_bit	Spi_Sck
spi_bit	Spi_MasterSlaveSelect
spi_bit	Spi_ClockBit0
spi_bit	Spi_ClockBit1
spi_bit	Spi_DoubleClock
spi_bit	Spi_Enable
spi_bit	Spi_InterruptEnable
spi_bit	Spi_InterruptFlag

Detailed Description

Spi.h declares SPI hardware types and variables common to the SPI Master and SPI Slave.

• SPI Master: usb-bridge
  
• SPI Slave: vis-spi-out
  

Definitions for I/O register and bit number depend on the compiler and target:

• lib/test/Spi-HardwareFake.h defines i/o for compiler gcc, target unit-test
• usb-bridge/src/Spi-Hardware.h defines i/o for compiler avr-gcc, target usb-bridge
• vis-spi-out/src/Spi-Hardware.h defines i/o for compiler avr-gcc, target vis-spi-out

A SPI interface usually only has four SPI pins:

• SS: Slave Select
• SCK: SPI Clock
• MOSI: Master data OUT, Slave data IN
• MISO: Master data IN, Slave data OUT

The development kit uses a 5th SPI pin:

• DR: Data Ready

Data Ready signals when vis-spi-out is ready for a SPI transmission:

• Data Ready is normally HIGH
• vis-spi-out drives Data Ready LOW to signal ready for transmission.
• vis-spi-out drives Data Ready HIGH when transmission is done.
• for multi-byte transmissions, Data Ready is driven LOW before each byte and HIGH after each byte.

API

uint8_t ReadSpiStatusRegister(void);
uint8_t ReadSpiDataRegister(void);
void ClearSpiInterruptFlag(void);

Definition in file Spi.h.

Function Documentation

_EnableSpiModule()

void _EnableSpiModule ( void  )

inline

Set SPE bit in SPCR (SPI Control Register) to enable SPI. This bit must be set to enable any SPI operations.

Definition at line 75 of file Spi.h.

_SpiTransferIsDone()

bool _SpiTransferIsDone ( void  )

inline

_SpiTransferIsDone behavior:

• returns true if the SPI Interrupt Flag is set
  
• returns false if the SPI Interrupt Flag is clear
  

Definition at line 88 of file Spi.h.

ClearSpiInterruptFlag()

void ClearSpiInterruptFlag ( void  )

inline

Manually clear SPI interrupt flag.

ClearSpiInterruptFlag behavior:

• first reads SPI status register
  
• then reads SPI data register
  

Definition at line 116 of file Spi.h.

Variable Documentation

Spi_SPDR

spi_reg Spi_SPDR

extern

SPI Data Register.

SPI Data Register.

Definition at line 26 of file SpiSlave-HardwareFake.h.