Serial Peripheral Interface

Defines
#define	spi_interrupt_enable()   (SPCR |= _BV(SPIE))
#define	spi_interrupt_disable()   (SPCR &= ~_BV(SPIE))
#define	spi_enable()   (SPCR |= _BV(SPE))
#define	spi_disable()   (SPCR |= _BV(SPE))
#define	spi_data_order_msb_first()   (SPCR &= ~_BV(DORD))
#define	spi_data_order_lsb_first()   (SPCR |= _BV(DORD))
#define	spi_mode_master()   (SPCR |= _BV(MSTR))
#define	spi_mode_slave()   (SPCR &= ~_BV(MSTR))
#define	spi_clock_idle_high()   (SPCR |= _BV(CPOL))
#define	spi_clock_idle_low()   (SPCR &= ~_BV(CPOL))
#define	spi_clock_sample_leading()   (SPCR &= ~_BV(CPHA))
#define	spi_clock_sample_trailing()   (SPCR |= _BV(CPHA))
#define	spi_write_collision_p()   ((SPSR >> WCOL) & 0x1)
Functions
void	spi_prescale_config (uint8_t prescale)

---

Define Documentation

 

#define spi_clock_idle_high

(

)

(SPCR |= _BV(CPOL))

Configure SPI device with clock idle high.

Author:

Andrew H. Fagg

 

#define spi_clock_idle_low

(

)

(SPCR &= ~_BV(CPOL))

Configure SPI device with clock idle low (default).

Author:

Andrew H. Fagg

 

#define spi_clock_sample_leading

(

)

(SPCR &= ~_BV(CPHA))

Configure SPI device with sample leading the clock edge (default).

Author:

Andrew H. Fagg

 

#define spi_clock_sample_trailing

(

)

(SPCR |= _BV(CPHA))

Configure SPI device with sample trailing the clock edge.

Author:

Andrew H. Fagg

 

#define spi_data_order_lsb_first

(

)

(SPCR |= _BV(DORD))

Configure SPI data order to be LSB first (default).

Author:

Andrew H. Fagg

 

#define spi_data_order_msb_first

(

)

(SPCR &= ~_BV(DORD))

Configure SPI data order to be MSB first

Author:

Andrew H. Fagg

 

#define spi_disable

(

)

(SPCR |= _BV(SPE))

Disable the SPI hardware device

Author:

Andrew H. Fagg

 

#define spi_enable

(

)

(SPCR |= _BV(SPE))

Enable the SPI hardware device

Author:

Andrew H. Fagg

 

#define spi_interrupt_disable

(

)

(SPCR &= ~_BV(SPIE))

Disable the SPI device interrupt

Author:

Andrew H. Fagg

 

#define spi_interrupt_enable

(

)

(SPCR |= _BV(SPIE))

Enable the SPI device interrupt

Author:

Andrew H. Fagg

 

#define spi_mode_master

(

)

(SPCR |= _BV(MSTR))

Configure SPI device as a master.

Author:

Andrew H. Fagg

 

#define spi_mode_slave

(

)

(SPCR &= ~_BV(MSTR))

Configure SPI device as a slave.

Author:

Andrew H. Fagg

 

#define spi_write_collision_p

(

)

((SPSR >> WCOL) & 0x1)

Check whether a write collision occurred.

Returns:

0: no collision has occurred
1: a collision has occurred

Author:

Andrew H. Fagg

---

Function Documentation

void spi_prescale_config

(

uint8_t

prescale

)

Configure the prescaler for the SPI master

Parameters:

prescale

One of: SPI_PRE_2 Divide system clock by 2 SPI_PRE_4 Divide by 4 SPI_PRE_8 Divide by 8 SPI_PRE_16 Divide by 16 SPI_PRE_32 Divide by 32 SPI_PRE_64 Divide by 64 SPI_PRE_64b Divide by 64 (??? why two) SPI_PRE_128 Divide by 128

Todo:

Understand why there are two cases of 64

Author:

Andrew H. Fagg