SerialWombatSWUART Class Reference

A class for the Serial Wombat 4B or SW18AB chips which creates a software based UART on the SW18AB. More...

#include <SerialWombatUART.h>

Inheritance diagram for SerialWombatSWUART:

Collaboration diagram for SerialWombatSWUART:

Public Member Functions
	SerialWombatSWUART (SerialWombatChip &serialWombatChip)
int16_t	begin (uint32_t baudRate, uint8_t pin, uint8_t rxPin, uint8_t txPin, uint16_t userMemoryOffset, uint16_t rxLength, uint16_t txLength)
int16_t	begin (uint32_t baudRate, uint8_t pin, uint8_t rxPin, uint8_t txPin, uint8_t HWinterface)=delete
	This method can't be called for Software UART because it doens't initialize queues in User Data Area.
size_t	write (const uint8_t *buffer, size_t size)
	Write bytes to the SerialWombatUART for Transmit.
size_t	readBytes (char *buffer, size_t length)
	Reads a specified number of bytes from the SerialWombatUART RX queue.
Public Member Functions inherited from SerialWombatUART
	SerialWombatUART (SerialWombatChip &serialWombat)
	Constructor for the SerialWombatUART class. Only one instance is allowed per SerialWombatChip 4B.
int16_t	begin (uint32_t baudRate, uint8_t pin, uint8_t rxPin, uint8_t txPin, uint8_t HWinterface=1)
virtual int	available ()
	Queries the SerialWombatUART for number bytes available to read.
virtual int	read ()
	Reads a byte from the SerialWombatUART.
virtual void	flush ()
	Discard all received bytes.
virtual int	peek ()
	Query the SerialWombatUART for the next avaialble byte, but don't remove it from the queue.
virtual size_t	write (uint8_t data)
	Write a byte to the SerialWombatUART for Transmit.
virtual int	availableForWrite ()
	Queries the SerialWombatUART for the amount of free TX queue space.
virtual void	setTimeout (long timeout_mS)
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 only.
int16_t	enablePullDown (bool enabled)
	Enables the weak pull down on a pin. Implemented on SW18AB only.
int16_t	enableOpenDrain (bool enabled)
	Enables open drain mode on a pin. Implemented on SW18AB only.

Public Attributes
SerialWombatQueue	rxQueue { _sw }
	SerialWombatQueue created on the Serial Wombat chip for data received by the SerialWombatSWUART.
SerialWombatQueue	txQueue { _sw }
	SerialWombatQueue created on the Serial Wombat chip for data to be sent by the SerialWombatSWUART.

Additional Inherited Members
Protected Attributes inherited from SerialWombatUART
uint8_t	_rxPin = 255
uint8_t	_txPin = 255
uint8_t	_baudMarker = 0
uint32_t	timeout = 5000
uint8_t	_pinMode = PIN_MODE_UART_RX_TX
uint8_t	_tx7Command = (uint8_t)SerialWombatCommands::COMMAND_UART0_TX_7BYTES
uint8_t	_rx7Command = (uint8_t)SerialWombatCommands::COMMAND_UART0_RX_7BYTES
Protected Attributes inherited from SerialWombatPin
uint8_t	_pin = 255
SerialWombatChip &	_sw
uint8_t	_pinMode = 0

Detailed Description

A class for the Serial Wombat 4B or SW18AB chips which creates a software based UART on the SW18AB.

A Tutorial video is avaialble:

https://youtu.be/C1FjcaiBYZs

The class inherits from the Arduino Sream class, so functions such as println() can be used once the Software UART is initialized.

Warning

Due to the overhead of querying and retreiving data from the SerialWombatUART, data loss is likely when receiving streams of data greater than the buffer size at higher baud rates.

Multiple instances of this class can be created on the Serial Wombat 18AB chip. This pin mode requires more CPU time than most, particularly for higher baud rate ports. Serial Wombat chip CPU usage should be checked if multiple software uarts are used. Exceeding the available SW18AB CPU resources will cause bit errors in the UART.

A queue in the User Buffer area is allocated for RX and one for TX prior to as part of begin for this mode. Size of these queues should be determined based on system needs. The User needs to ensure that the created queues do not overlap with other structures created in the User Buffer

A full Serial Wombat packet send / receive sequence (8 bytes in each direction) over I2C or the main UART is necessary to query the status of the queues or to read or receive a byte of data.

The protocol becomes more efficient if multiple bytes are read or written using the readBytes or write(const uint8_t* buffer, size_t size) interfaces rather than read() or write(uint8_t data).

The class must be assigned to a pin. This may be either the receive or transmit pin.

Available baud rates are:

• 300
  
• 1200
• 2400
  
• 4800
  
• 9600
  
• 19200
• 38400 (Transmit only, receive may be unreliable )
• 57600 (Transmit only, receive may be unreliable )

Definition at line 478 of file SerialWombatUART.h.

Constructor & Destructor Documentation

SerialWombatSWUART()

SerialWombatSWUART::SerialWombatSWUART ( SerialWombatChip & serialWombatChip )

inline

Definition at line 484 of file SerialWombatUART.h.

Member Function Documentation

begin() [1/2]

int16_t SerialWombatSWUART::begin ( uint32_t baudRate, uint8_t pin, uint8_t rxPin, uint8_t txPin, uint16_t userMemoryOffset, uint16_t rxLength, uint16_t txLength )

inline

Parameters

baudRate	300, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200
pin	The pin that will host the state machine. This can be either the rxPin or txPin
rxPin	The pin that will receive. All 4 pins on the SW4B may be used. 255 if no receive function is needed
txPin	The pin that will transmit. Valid values for the SW4B are 1-3. 255 if no transmit function is needed
userMemoryoffset	The offset into User Memory where the software storage queues begin
rxLength	The length in bytes of the on-chip rx queue (can be 0 if rxPin == 255).
txLength	The length in bytes of the on-chip tx queue (can be 0 if txPin == 255).

Definition at line 494 of file SerialWombatUART.h.

begin() [2/2]

int16_t SerialWombatSWUART::begin ( uint32_t baudRate, uint8_t pin, uint8_t rxPin, uint8_t txPin, uint8_t HWinterface )

delete

This method can't be called for Software UART because it doens't initialize queues in User Data Area.

readBytes()

size_t SerialWombatSWUART::readBytes ( char * buffer, size_t length )

inlinevirtual

Reads a specified number of bytes from the SerialWombatUART RX queue.

Parameters

buffer	An array into which to put received bytes
length	The maximum number of bytes to be received

Returns

the number of bytes written to buffer

This function will read bytes from the SerialWombatUART RX queue into buffer. If 'length' characters are not available to read then the value returned will be less than length.

Reimplemented from SerialWombatUART.

Definition at line 626 of file SerialWombatUART.h.

write()

size_t SerialWombatSWUART::write ( const uint8_t * buffer, size_t size )

inlinevirtual

Write bytes to the SerialWombatUART for Transmit.

Parameters

buffer	An array of uint8_t bytes to send
size	the number of bytes to send

Returns

the number of bytes sent

This function queries the SerialWombatSWUART for avaialble TX buffer space, and sends bytes as buffer space is avaialble. If avaialable buffer space is not sufficient to send the entire array then the function will block and continue trying until the entire message has been sent to the SerialWombatUART transmit queue.

Reimplemented from SerialWombatUART.

Definition at line 611 of file SerialWombatUART.h.

Member Data Documentation

rxQueue

SerialWombatQueue SerialWombatSWUART::rxQueue { _sw }

SerialWombatQueue created on the Serial Wombat chip for data received by the SerialWombatSWUART.

Definition at line 635 of file SerialWombatUART.h.

txQueue

SerialWombatQueue SerialWombatSWUART::txQueue { _sw }

SerialWombatQueue created on the Serial Wombat chip for data to be sent by the SerialWombatSWUART.

Definition at line 639 of file SerialWombatUART.h.