edu.wpi.first.wpilibj

Class SPI

java.lang.Object

edu.wpi.first.wpilibj.SensorBase

edu.wpi.first.wpilibj.SPI

public class SPI
extends SensorBase

Represents a SPI bus port.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SPI.Port

Field Summary

Fields inherited from class edu.wpi.first.wpilibj.SensorBase

kAnalogInputChannels, kAnalogOutputChannels, kDigitalChannels, kPCMModules, kPDPChannels, kPDPModules, kPwmChannels, kRelayChannels, kSolenoidChannels, kSystemClockTicksPerMicrosecond

Constructor Summary

Constructors

Constructor and Description
SPI(SPI.Port port) Constructor.

Method Summary

Modifier and Type	Method and Description
void	free() Free the resources used by this object.
void	freeAccumulator() Frees the accumulator.
double	getAccumulatorAverage() Read the average of the accumulated value.
int	getAccumulatorCount() Read the number of accumulated values.
int	getAccumulatorLastValue() Read the last value read by the accumulator engine.
void	getAccumulatorOutput(AccumulatorResult result) Read the accumulated value and the number of accumulated values atomically.
long	getAccumulatorValue() Read the accumulated value.
void	initAccumulator(double period, int cmd, int xferSize, int validMask, int validValue, int dataShift, int dataSize, boolean isSigned, boolean bigEndian) Initialize the accumulator.
int	read(boolean initiate, byte[] dataReceived, int size) Read a word from the receive FIFO.
int	read(boolean initiate, java.nio.ByteBuffer dataReceived, int size) Read a word from the receive FIFO.
void	resetAccumulator() Resets the accumulator to zero.
void	setAccumulatorCenter(int center) Set the center value of the accumulator.
void	setAccumulatorDeadband(int deadband) Set the accumulator's deadband.
void	setChipSelectActiveHigh() Configure the chip select line to be active high.
void	setChipSelectActiveLow() Configure the chip select line to be active low.
void	setClockActiveHigh() Configure the clock output line to be active high.
void	setClockActiveLow() Configure the clock output line to be active low.
void	setClockRate(int hz) Configure the rate of the generated clock signal.
void	setLSBFirst() Configure the order that bits are sent and received on the wire to be least significant bit first.
void	setMSBFirst() Configure the order that bits are sent and received on the wire to be most significant bit first.
void	setSampleDataOnFalling() Configure that the data is stable on the falling edge and the data changes on the rising edge.
void	setSampleDataOnRising() Configure that the data is stable on the rising edge and the data changes on the falling edge.
int	transaction(byte[] dataToSend, byte[] dataReceived, int size) Perform a simultaneous read/write transaction with the device.
int	transaction(java.nio.ByteBuffer dataToSend, java.nio.ByteBuffer dataReceived, int size) Perform a simultaneous read/write transaction with the device
int	write(byte[] dataToSend, int size) Write data to the slave device.
int	write(java.nio.ByteBuffer dataToSend, int size) Write data to the slave device.

Methods inherited from class edu.wpi.first.wpilibj.SensorBase

checkAnalogInputChannel, checkAnalogOutputChannel, checkDigitalChannel, checkPDPChannel, checkPDPModule, checkPWMChannel, checkRelayChannel, checkSolenoidChannel, checkSolenoidModule, getDefaultSolenoidModule, setDefaultSolenoidModule

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SPI

public SPI(SPI.Port port)

Constructor.

Parameters:

port - the physical SPI port

Method Detail

free

public void free()

Free the resources used by this object.

Overrides:

free in class SensorBase

setClockRate

public final void setClockRate(int hz)

Configure the rate of the generated clock signal. The default value is 500,000 Hz. The maximum value is 4,000,000 Hz.

Parameters:

hz - The clock rate in Hertz.

setMSBFirst

public final void setMSBFirst()

Configure the order that bits are sent and received on the wire to be most significant bit first.

setLSBFirst

public final void setLSBFirst()

Configure the order that bits are sent and received on the wire to be least significant bit first.

setClockActiveLow

public final void setClockActiveLow()

Configure the clock output line to be active low. This is sometimes called clock polarity high or clock idle high.

setClockActiveHigh

public final void setClockActiveHigh()

Configure the clock output line to be active high. This is sometimes called clock polarity low or clock idle low.

setSampleDataOnFalling

public final void setSampleDataOnFalling()

Configure that the data is stable on the falling edge and the data changes on the rising edge.

setSampleDataOnRising

public final void setSampleDataOnRising()

Configure that the data is stable on the rising edge and the data changes on the falling edge.

setChipSelectActiveHigh

public final void setChipSelectActiveHigh()

Configure the chip select line to be active high.

setChipSelectActiveLow

public final void setChipSelectActiveLow()

Configure the chip select line to be active low.

write

public int write(byte[] dataToSend,
                 int size)

Write data to the slave device. Blocks until there is space in the output FIFO.

If not running in output only mode, also saves the data received on the MISO input during the transfer into the receive FIFO.

write

public int write(java.nio.ByteBuffer dataToSend,
                 int size)

Write data to the slave device. Blocks until there is space in the output FIFO.

If not running in output only mode, also saves the data received on the MISO input during the transfer into the receive FIFO.

Parameters:

dataToSend - The buffer containing the data to send. Must be created using ByteBuffer.allocateDirect().

read

public int read(boolean initiate,
                byte[] dataReceived,
                int size)

Read a word from the receive FIFO.

Waits for the current transfer to complete if the receive FIFO is empty.

If the receive FIFO is empty, there is no active transfer, and initiate is false, errors.

Parameters:

initiate - If true, this function pushes "0" into the transmit buffer and initiates a transfer. If false, this function assumes that data is already in the receive FIFO from a previous write.

read

public int read(boolean initiate,
                java.nio.ByteBuffer dataReceived,
                int size)

Read a word from the receive FIFO.

Waits for the current transfer to complete if the receive FIFO is empty.

If the receive FIFO is empty, there is no active transfer, and initiate is false, errors.

Parameters:

initiate - If true, this function pushes "0" into the transmit buffer and initiates a transfer. If false, this function assumes that data is already in the receive FIFO from a previous write.

dataReceived - The buffer to be filled with the received data. Must be created using ByteBuffer.allocateDirect().

size - The length of the transaction, in bytes

transaction

public int transaction(byte[] dataToSend,
                       byte[] dataReceived,
                       int size)

Perform a simultaneous read/write transaction with the device.

Parameters:

dataToSend - The data to be written out to the device

dataReceived - Buffer to receive data from the device

size - The length of the transaction, in bytes

transaction

public int transaction(java.nio.ByteBuffer dataToSend,
                       java.nio.ByteBuffer dataReceived,
                       int size)

Perform a simultaneous read/write transaction with the device

Parameters:

dataToSend - The data to be written out to the device. Must be created using ByteBuffer.allocateDirect().

dataReceived - Buffer to receive data from the device. Must be created using ByteBuffer.allocateDirect().

size - The length of the transaction, in bytes

initAccumulator

public void initAccumulator(double period,
                            int cmd,
                            int xferSize,
                            int validMask,
                            int validValue,
                            int dataShift,
                            int dataSize,
                            boolean isSigned,
                            boolean bigEndian)

Initialize the accumulator.

Parameters:

period - Time between reads

cmd - SPI command to send to request data

xferSize - SPI transfer size, in bytes

validMask - Mask to apply to received data for validity checking

validValue - After validMask is applied, required matching value for validity checking

dataShift - Bit shift to apply to received data to get actual data value

dataSize - Size (in bits) of data field

isSigned - Is data field signed?

bigEndian - Is device big endian?

freeAccumulator

public void freeAccumulator()

Frees the accumulator.

resetAccumulator

public void resetAccumulator()

Resets the accumulator to zero.

setAccumulatorCenter

public void setAccumulatorCenter(int center)

Set the center value of the accumulator.

The center value is subtracted from each value before it is added to the accumulator. This is used for the center value of devices like gyros and accelerometers to make integration work and to take the device offset into account when integrating.

setAccumulatorDeadband

public void setAccumulatorDeadband(int deadband)

Set the accumulator's deadband.

getAccumulatorLastValue

public int getAccumulatorLastValue()

Read the last value read by the accumulator engine.

getAccumulatorValue

public long getAccumulatorValue()

Read the accumulated value.

Returns:

The 64-bit value accumulated since the last Reset().

getAccumulatorCount

public int getAccumulatorCount()

Read the number of accumulated values.

Read the count of the accumulated values since the accumulator was last Reset().

Returns:

The number of times samples from the channel were accumulated.

getAccumulatorAverage

public double getAccumulatorAverage()

Read the average of the accumulated value.

Returns:

The accumulated average value (value / count).

getAccumulatorOutput

public void getAccumulatorOutput(AccumulatorResult result)

Read the accumulated value and the number of accumulated values atomically.

This function reads the value and count atomically. This can be used for averaging.

Parameters:

result - AccumulatorResult object to store the results in.