spi0_master.h File Reference

#include <cc2511_map.h>
#include <cc2511_types.h>
#include <spi.h>

Go to the source code of this file.

Functions
void	spi0MasterInit (void)
void	spi0MasterSetFrequency (uint32 freq)
void	spi0MasterSetClockPolarity (BIT polarity)
void	spi0MasterSetClockPhase (BIT phase)
void	spi0MasterSetBitOrder (BIT bitOrder)
BIT	spi0MasterBusy (void)
uint16	spi0MasterBytesLeft (void)
void	spi0MasterTransfer (const uint8 XDATA *txBuffer, uint8 XDATA *rxBuffer, uint16 size)
uint8	spi0MasterSendByte (uint8 XDATA byte)
uint8	spi0MasterReceiveByte (void)
	ISR (URX0, 0)

Detailed Description

The spi_master.lib library allows you to do SPI master communication using USART0 and/or USART1. This library uses interrupts to transfer data so it is capable of sending/receiving in the background while other tasks are performed.

To use this library, you must include spi0_master.h or spi1_master.h in your app:

#include <spi0_master.h>
#include <spi1_master.h>

Since this library uses interrupts, the include statement must be present in the file that contains main().

The API for using USART1 is the same as the API for using USART0 that is documented here, except all the function and variable names begin with "spi1Master" instead of "spi0Master".

For USART0, this library uses Alternative Location 1: P0_5 is SCK, P0_3 is MOSI, and P0_2 is MISO.

For USART1, this library uses Alternative Location 2: P1_5 is SCK, P1_6 is MOSI, P1_7 is MISO.

This library does not yet allow you to choose which alternative location to use.

Please note that this library only supports SPI master communication; MOSI and SCK are outputs and MISO is an input.

Definition in file spi0_master.h.

Function Documentation

ISR	(	URX0	,
		0
	)

A prototype for the USART0 interrupt.

BIT spi0MasterBusy

(

void

)

Returns

1 if the library is busy transferring of data, 0 if it is not busy.

This is equivalent to spi0MasterBytesLeft() != 0 but it is faster and doesn't affect the speed of the transfer.

uint16 spi0MasterBytesLeft

(

void

)

Returns

The number of bytes left to transfer in the current transfer. If 0, it means there is no current transfer.

This function temporarily disables the interrupt used by this library to transfer data, so calling this function frequently could reduce the speed that data is transferred. If possible, try to use spi0MasterBusy() instead of this function.

void spi0MasterInit

(

void

)

Initializes the library.

This must be called before any other functions with names that begin with "spi0Master".

After calling this, it is recommended to call spi0MasterSetFrequency(), spi0MasterSetClockPolarity(), spi0MasterSetClockPhase(), and spi0MasterSetBitOrder() to set the other parameters of the SPI communication.

uint8 spi0MasterReceiveByte

(

void

)

This is equivalent to:

spi0MasterSendByte(0xFF)

uint8 spi0MasterSendByte

(

uint8 XDATA

byte

)

Transmits one byte to the SPI slave, simultaneously receiving a byte from the slave. This is a synchronous, blocking function so be careful about using it in apps that have regular tasks to perform.

This function should not be called if the library is busy doing a transfer (i.e. spi0MasterBusy() returns 1).

Parameters

byte	The byte to send to the slave.

Returns

The byte received from the slave.

void spi0MasterSetBitOrder

(

BIT

bitOrder

)

Sets the bit order for transfers. Valid values are:

• SPI_BIT_ORDER_MSB_FIRST: The most-significant bit is transmitted first.
• SPI_BIT_ORDER_LSB_FIRST: The least-significant bit is transmitted first.

void spi0MasterSetClockPhase

(

BIT

phase

)

Sets the clock phase (the bit named CPHA in U0GCR). This bit controls the phase of the clock, which determines what type of transition is occurring when the data is sampled/transmitted. Valid values are:

• SPI_PHASE_EDGE_LEADING (0): Data is sampled/transmitted on the leading edge, when the clock line transitions from idle to active.
• SPI_PHASE_EDGE_TRAILING (1): Data is sampled/transmitted on the trailing edge, when the clock like transitions from active to idle.

For more information, see Figure 41 (SPI Dataflow) in the CC2511F32 datasheet.

void spi0MasterSetClockPolarity

(

BIT

polarity

)

Sets the clock polarity (the bit named CPOL in U0GCR). This bit can be used to invert the signal on SCK. Valid values are:

• SPI_POLARITY_IDLE_LOW (0): The SCK line will be low when no data is being transferred.
• SPI_POLARITY_IDLE_HIGH (1): The SCK line will be high when no data is being transferred.

For more information, see Figure 41 (SPI Dataflow) in the CC2511F32 datasheet.

void spi0MasterSetFrequency

(

uint32

freq

)

Sets the frequency of the clock signal on SCK.

Parameters

freq	The frequency, in bits per second. Must be between 23 and 3,000,000.

void spi0MasterTransfer	(	const uint8 XDATA *	txBuffer,
		uint8 XDATA *	rxBuffer,
		uint16	size
	)

Starts a new transfer of data. The transfer will be carried out in the background by interrupts, allowing other tasks to be performed simultaneously. This is a non-blocking function.

Parameters

txBuffer	A pointer to a buffer holding the bytes to be sent to the SPI slave.
rxBuffer	A pointer to a buffer to hold bytes received by the SPI slave during this transfer. This may be equal to txBuffer, which would cause the transmitted data to be overwritten with received data.
size	The number of bytes to transmit/receive.

This function should not be called if the library is busy doing a transfer (i.e. spi0MasterBusy() returns 1).

In SPI, every transfer of data consists of one byte going from the master to the slave and one byte going from the slave to the master. Not every byte is meaningful: often dummy data is inserted. This function initiates a transmission of several bytes from the master (the Wixel) to the slave. During this transmission, an equal number of bytes will be received and stored in the RX buffer.