SerialWombatSPI Class Reference

A pin mode for the Serial Wombat 8B or SW18AB chips which allows SPI communication over I2C. More...

#include <SerialWombatSPI.h>

Inheritance diagram for SerialWombatSPI:

Collaboration diagram for SerialWombatSPI:

Public Member Functions
	SerialWombatSPI (SerialWombatChip &serialWombat)
	Constructor for the SerialWombatSPI class.
int16_t	begin (uint8_t pin, uint8_t SPIModeparam, uint8_t MOSIpin=255, uint8_t MISOpin=255, uint8_t CSpin=255)
uint8_t	transfer (uint8_t data, bool csSaysStayLow=false)
uint16_t	transfer (uint16_t data, bool csSaysStayLow=false)
void	transfer (void *buf, size_t count, bool csSaysStayLow=false)
int16_t	transferPacketUpTo32Bits (uint8_t *outBuf, uint8_t *inBuf, size_t bitCount, bool csSaysStayLow=false)
int16_t	transferPacket40Bits (uint8_t *outBuf, uint8_t *inBuf, bool csSaysStayLow=false)
int16_t	setCSHigh ()
Public Member Functions inherited from SerialWombatPin
	SerialWombatPin (SerialWombatChip &serialWombatChip)
	Instantiates a Serial Wombat Pin.
	SerialWombatPin (SerialWombatChip &serialWombatChip, uint8_t pin)
	Instantiates a Serial Wombat Pin.
uint16_t	readPublicData ()
	Read the 16 Bit public data associated with this pin.
void	pinMode (uint8_t mode, bool pullDown=false, bool openDrain=false)
	Set pin to INPUT or OUTPUT, with options for pull Ups and open Drain settings.
void	digitalWrite (uint8_t val)
	Set output pin High or Low.
int	digitalRead ()
	Reads the state of the Pin.
uint16_t	writePublicData (uint16_t value)
	Write a 16 bit value to this pin.
uint8_t	pin ()
	Returns the current SW pin number. Used primarily for virtual calls by derived classes.
uint8_t	swPinModeNumber ()
	Returns the Mode number. Used primarily by derived classes to populate packet data.
int16_t	initPacketNoResponse (uint8_t packetNumber, uint8_t param0=0x55, uint8_t param1=0x55, uint8_t param2=0x55, uint8_t param3=0x55, uint8_t param4=0x55)
int16_t	initPacketNoResponse (uint8_t packetNumber, uint16_t param0=0x55, uint8_t param1=0x55, uint8_t param2=0x55, uint8_t param3=0x55)
int16_t	initPacketNoResponse (uint8_t packetNumber, uint16_t param0, uint16_t param1, uint8_t param2=0x55)
int16_t	disable ()
	Disables the pin mode (if applicable)
int16_t	enablePullup (bool enabled)
	Enables the weak pull up on a pin. Implemented on SW18AB and SW8B only.
int16_t	enablePulldown (bool enabled)
	Enables the weak pull down on a pin. Implemented on SW18AB and SW8B only.
int16_t	enableOpenDrain (bool enabled)
	Enables open drain mode on a pin. Implemented on SW18AB and SW8B only.
int16_t	forceDMA (bool enabled)
	Forces use of DMA instead of hardware timing resources on SW18AB.
void	setPinNumberForTesting (uint8_t pin)
	A function designed for testing only. May have unpredictable results if used in real time. Not intended for general use.

Static Public Member Functions
static void	beginTransaction (SerialWombatSPISettings settings)
static void	end ()

Additional Inherited Members
Protected Attributes inherited from SerialWombatPin
uint8_t	_pin = 255
SerialWombatChip &	_sw
uint8_t	_pinMode = 0

Detailed Description

A pin mode for the Serial Wombat 8B or SW18AB chips which allows SPI communication over I2C.

This pin mode allows the Serial Wombat 8B or SW18AB to send and receive SPI data over I2C. This pin mode is good for low to moderate bandwidth SPI devices due to the overhead of the I2C bus. Suggested applications include shfit registers, low speed ADC, and LED current drivers. This pin mode is intended as a much more efficient alternative to bit-banging SPI using pin high and low I2C commands.

This pin mode is assigned to the clock pin. Additonal pins can be assigned as MOSI, MISO and CS pins.
The clock speed is not configurable, and is about 250kHz on the SW8B.

Unlike other pin modes, all functionality of this pin mode occurs during the I2C communcation handling instead of the 1mS pin update. This is not a problem for the SW8B because it only has to service 6 or less other pins every 1mS, but for the 18AB can be problematic if many other pins are in use as the time to bit-bang the SPI transaction may cause frame overflows. For the 8B up to 5 SPI bytes can be transferred per I2C transaction, but for the 18AB only 1 byte can be transferred by default to minimize the chance of frame overflows.

SPI modes 0, 1, and 3 are supported. Mode 2 is not a commonly used mode, and is left out to reduce the flash space required by the pin mode.

If a chip select pin is specified the chip select is set low before the SPI transaction. The chip select can be configured to stay low or go high after completion of the SPI transaction allowing for long transactions.

This pin mode is designed to function similarly to the Arduino SPIClass with similar interfaces. Unlike Arduino there are no interupt based options, the clock speed is fixed, and the bitOrder is ignored (always MSB first).

See the Examples in the examples area for usage.

A Tutorial video is avaialble:

https://youtu.be/TPwNbclAd5s

SerialWombatSPI overview

Definition at line 97 of file SerialWombatSPI.h.

Constructor & Destructor Documentation

SerialWombatSPI()

SerialWombatSPI::SerialWombatSPI ( SerialWombatChip & serialWombat )

inline

Constructor for the SerialWombatSPI class.

Parameters

serialWombat

The Serial Wombat chip on which the SerialWombatSPI instance will run.

Definition at line 104 of file SerialWombatSPI.h.

Member Function Documentation

begin()

int16_t SerialWombatSPI::begin ( uint8_t pin, uint8_t SPIModeparam, uint8_t MOSIpin = 255, uint8_t MISOpin = 255, uint8_t CSpin = 255 )

inline

@brief Initalize the SerialWombatSPI.  

Parameters

pin	The pin that will host the state machine.
SPIMode	0, 1 or 3. Mode 2 is not supported to save flash space.
MOSIpin	Optional pin number for MOSI. Set to 255 to not use a MOSI pin.
MISOpin	Optional pin number for MISO. Set to 255 to not use a MISO pin.
CSpin	Optional pin number for Chip Select. Set to 255 to not use a chip select pin.

Returns

negative error code or positive success

Definition at line 116 of file SerialWombatSPI.h.

beginTransaction()

static void SerialWombatSPI::beginTransaction ( SerialWombatSPISettings settings )

inlinestatic

Definition at line 147 of file SerialWombatSPI.h.

end()

static void SerialWombatSPI::end ( )

inlinestatic

Definition at line 154 of file SerialWombatSPI.h.

setCSHigh()

int16_t SerialWombatSPI::setCSHigh ( )

inline

Definition at line 341 of file SerialWombatSPI.h.

transfer() [1/3]

uint16_t SerialWombatSPI::transfer ( uint16_t data, bool csSaysStayLow = false )

inline

Definition at line 186 of file SerialWombatSPI.h.

transfer() [2/3]

uint8_t SerialWombatSPI::transfer ( uint8_t data, bool csSaysStayLow = false )

inline

Definition at line 162 of file SerialWombatSPI.h.

transfer() [3/3]

void SerialWombatSPI::transfer ( void * buf, size_t count, bool csSaysStayLow = false )

inline

Definition at line 209 of file SerialWombatSPI.h.

transferPacket40Bits()

int16_t SerialWombatSPI::transferPacket40Bits ( uint8_t * outBuf, uint8_t * inBuf, bool csSaysStayLow = false )

inline

Definition at line 315 of file SerialWombatSPI.h.

transferPacketUpTo32Bits()

int16_t SerialWombatSPI::transferPacketUpTo32Bits ( uint8_t * outBuf, uint8_t * inBuf, size_t bitCount, bool csSaysStayLow = false )

inline

Definition at line 281 of file SerialWombatSPI.h.