Difference between revisions of "Unit SPI"

Revision as of 00:26, 30 November 2022

The SPI protocol is not defined by any actual standard but some pseudo standards exist with all of the available devices. SPI is a master-slave protocol where the master asserts the chip select line (CS) to select the slave device before sending data one byte at a time. For every byte written to the bus by the master the selected slave returns a byte as well so for every write there is an equivalent read. SPI can also operate in either 4 wire (standard) or 3 wire(bidirectional) modes.

Due to the lack of formal standards and the range of devices that exist various options are provided to allow setting clock phase and polarity as well chip select polarity.

For the purpose of this interface a device is the SPI controller attached to the local system and may be either a master or a slave. Since the protocol does not include any form of enumeration or identification the interface does not attempt to represent the devices connected to the bus, any driver written to communicate with a connected SPI device should know (or allow configuration of) the chip select for the for the device and the specific message format required for that device.

Constants

SPI specific constants SPI_*

`SPI_NAME_PREFIX = 'SPI';`	Name prefix for SPI Devices

SPI device type SPI_TYPE_*

`SPI_TYPE_NONE = 0;`

`SPI_TYPE_MAX = 0;`

SPI device state SPI_STATE_*

`SPI_STATE_DISABLED = 0;`
`SPI_STATE_ENABLED = 1;`

`SPI_STATE_MAX = 1;`

SPI device flag SPI_FLAG_*

`SPI_FLAG_NONE = $00000000;`
`SPI_FLAG_SLAVE = $00000001;`	Device is a slave not a master
`SPI_FLAG_4WIRE = $00000002;`	Device supports 4 wire operation (CS/MISO/MOSI/SCLK)
`SPI_FLAG_3WIRE = $00000004;`	Device supports 3 wire operation (CS/MIMO/SCLK)
`SPI_FLAG_LOSSI = $00000008;`	Device supports LoSSI (Low Speed Serial) mode (CS/SCL/SDA)
`SPI_FLAG_CPOL = $00000010;`	Device supports Clock Polarity setting
`SPI_FLAG_CPHA = $00000020;`	Device supports Clock Phase setting
`SPI_FLAG_CSPOL = $00000040;`	Device supports Chip Select Polarity setting
`SPI_FLAG_NO_CS = $00000080;`	Device supports Chip Select None (CS handled externally)
`SPI_FLAG_DMA = $00000100;`	Device supports DMA transfers

SPI transfer flag SPI_TRANSFER_*

`SPI_TRANSFER_NONE = $00000000;`
`SPI_TRANSFER_DMA = $00000001;`	Use DMA for transfer (Write/Read) (Note: Buffers must be DMA compatible)
`SPI_TRANSFER_PIO = $00000002;`	Use PIO (Polling) for transfer (Write/Read)

`SPI_TRANSFER_DELAY = $00000004;`	Add a delay after each byte written (Write/Read) Note: Only available with PIO transfer unless provided directly by hardware

SPI logging SPI_LOG_*

`SPI_LOG_LEVEL_DEBUG = LOG_LEVEL_DEBUG;`	SPI debugging messages
`SPI_LOG_LEVEL_INFO = LOG_LEVEL_INFO;`	SPI informational messages, such as a device being attached or detached
`SPI_LOG_LEVEL_WARN = LOG_LEVEL_WARN;`	SPI warning messages
`SPI_LOG_LEVEL_ERROR = LOG_LEVEL_ERROR;`	SPI error messages
`SPI_LOG_LEVEL_NONE = LOG_LEVEL_NONE;`	No SPI messages

Type definitions

SPI properties

PSPIProperties = ^TSPIProperties;

TSPIProperties = record

`Flags:LongWord;`	Device flags (eg SPI_FLAG_SLAVE)
`MaxSize:LongWord;`	Maximum supported data transfer size
`MinClock:LongWord;`	Minimum supported clock rate
`MaxClock:LongWord;`	Maximum supported clock rate
`SelectCount:LongWord;`	Number of chip selects supported
`Mode:LongWord;`	Current mode (eg SPI_MODE_4WIRE)
`ClockRate:LongWord;`	Current clock rate
`ClockPhase:LongWord;`	Current clock phase (CPHA) (eg SPI_CLOCK_PHASE_LOW)
`ClockPolarity:LongWord;`	Current clock polarity (CPOL) (eg SPI_CLOCK_POLARITY_LOW)
`SelectPolarity:LongWord;`	Default chip select polarity (eg SPI_CS_POLARITY_LOW)
`ByteDelay:LongWord;`	Delay between bytes written (Microseconds)

SPI chip select

PSPIChipSelect = ^TSPIChipSelect;

TSPIChipSelect = record

`Pin:LongWord;`	The GPIO pin for this chip select (eg GPIO_PIN_46)(GPIO_PIN_UNKNOWN for internal)
`Mode:LongWord;`	The mode for this chip select (eg SPI_MODE_0)
`Divider:LongWord;`	The clock divider for this chip select (Used internally by drivers)
`ClockRate:LongWord;`	The clock rate for this chip select
`ClockPhase:LongWord;`	The clock phase (CPHA) for this chip select (eg SPI_CLOCK_PHASE_LOW)
`ClockPolarity:LongWord;`	The clock polarity (CPOL) for this chip select (eg SPI_CLOCK_POLARITY_LOW)
`SelectPolarity:LongWord;`	The chip select polarity for this chip select (eg SPI_CS_POLARITY_LOW)
`ByteDelay:LongWord;`	Delay between bytes written for this chip select (Microseconds)

SPI enumeration callback

`TSPIEnumerate = function(SPI:PSPIDevice; Data:Pointer):LongWord;`

SPI notification callback

`TSPINotification = function(Device:PDevice; Data:Pointer; Notification:LongWord):LongWord;`

SPI device start

`TSPIDeviceStart = function(SPI:PSPIDevice; Mode,ClockRate,ClockPhase,ClockPolarity:LongWord):LongWord;`

SPI device stop

`TSPIDeviceStop = function(SPI:PSPIDevice):LongWord;`

SPI device read

`TSPIDeviceRead = function(SPI:PSPIDevice; ChipSelect:Word; Dest:Pointer; Size,Flags:LongWord; var Count:LongWord):LongWord;`

SPI device write

`TSPIDeviceWrite = function(SPI:PSPIDevice; ChipSelect:Word; Source:Pointer; Size,Flags:LongWord; var Count:LongWord):LongWord;`

SPI device write read

`TSPIDeviceWriteRead = function(SPI:PSPIDevice; ChipSelect:Word; Source,Dest:Pointer; Size,Flags:LongWord; var Count:LongWord):LongWord;`

SPI device get mode

`TSPIDeviceGetMode = function(SPI:PSPIDevice):LongWord;`

SPI device set mode

`TSPIDeviceSetMode = function(SPI:PSPIDevice; Mode:LongWord):LongWord;`

SPI device get clock rate

`TSPIDeviceGetClockRate = function(SPI:PSPIDevice; ChipSelect:Word):LongWord;`

SPI device set clock rate

`TSPIDeviceSetClockRate = function(SPI:PSPIDevice; ChipSelect:Word; ClockRate:LongWord):LongWord;`

SPI device get clock phase

`TSPIDeviceGetClockPhase = function(SPI:PSPIDevice):LongWord;`

SPI device set clock phase

`TSPIDeviceSetClockPhase = function(SPI:PSPIDevice; ClockPhase:LongWord):LongWord;`

SPI device get clock polarity

`TSPIDeviceGetClockPolarity = function(SPI:PSPIDevice):LongWord;`

SPI device set clock polarity

`TSPIDeviceSetClockPolarity = function(SPI:PSPIDevice; ClockPolarity:LongWord):LongWord;`

SPI device get select polarity

`TSPIDeviceGetSelectPolarity = function(SPI:PSPIDevice; ChipSelect:Word):LongWord;`

SPI device set select polarity

`TSPIDeviceSetSelectPolarity = function(SPI:PSPIDevice; ChipSelect:Word; SelectPolarity:LongWord):LongWord;`

SPI device get byte delay

`TSPIDeviceGetByteDelay = function(SPI:PSPIDevice):LongWord;`

SPI device set byte delay

`TSPIDeviceSetByteDelay = function(SPI:PSPIDevice; Delay:LongWord):LongWord;`

SPI device get properties

`TSPIDeviceGetProperties = function(SPI:PSPIDevice; Properties:PSPIProperties):LongWord;`

SPI device

PSPIDevice = ^TSPIDevice;

TSPIDevice = record

Device Properties
`Device:TDevice;`	The Device entry for this SPI
SPI Properties
`SPIId:LongWord;`	Unique Id of this SPI in the SPI table
`SPIState:LongWord;`	SPI state (eg SPI_STATE_ENABLED)
`SPIMode:LongWord;`	SPI mode (eg SPI_MODE_4WIRE)
`DeviceStart:TSPIDeviceStart;`	A Device specific DeviceStart method implementing the standard SPI device interface (Mandatory)
`DeviceStop:TSPIDeviceStop;`	A Device specific DeviceStop method implementing the standard SPI device interface (Mandatory)
`DeviceRead:TSPIDeviceRead;`	A Device specific DeviceRead method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceWrite:TSPIDeviceWrite;`	A Device specific DeviceWrite method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceWriteRead:TSPIDeviceWriteRead;`	A Device specific DeviceWriteRead method implementing the standard SPI device interface (Mandatory)
`DeviceGetMode:TSPIDeviceGetMode;`	A Device specific DeviceGetMode method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceSetMode:TSPIDeviceSetMode;`	A Device specific DeviceSetMode method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceGetClockRate:TSPIDeviceGetClockRate;`	A Device specific DeviceGetClockRate method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceSetClockRate:TSPIDeviceSetClockRate;`	A Device specific DeviceSetClockRate method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceGetClockPhase:TSPIDeviceGetClockPhase;`	A Device specific DeviceGetClockPhase method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceSetClockPhase:TSPIDeviceSetClockPhase;`	A Device specific DeviceSetClockPhase method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceGetClockPolarity:TSPIDeviceGetClockPolarity;`	A Device specific DeviceGetClockPolarity method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceSetClockPolarity:TSPIDeviceSetClockPolarity;`	A Device specific DeviceSetClockPolarity method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceGetSelectPolarity:TSPIDeviceGetSelectPolarity;`	A Device specific DeviceGetSelectPolarity method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceSetSelectPolarity:TSPIDeviceSetSelectPolarity;`	A Device specific DeviceSetSelectPolarity method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceGetByteDelay:TSPIDeviceGetByteDelay;`	A Device specific DeviceGetByteDelay method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceSetByteDelay:TSPIDeviceSetByteDelay;`	A Device specific DeviceSetByteDelay method implementing the standard SPI device interface (Or nil if the default method is suitable)
`DeviceGetProperties:TSPIDeviceGetProperties;`	A Device specific DeviceGetProperties method implementing the standard SPI device interface (Or nil if the default method is suitable)
Statistics Properties
`TransferCount:LongWord;`
`TransferErrors:LongWord;`
Driver Properties
`Lock:TMutexHandle;`	Device lock
`Wait:TSemaphoreHandle;`	Write/Read wait event
`Divider:LongWord;`	Clock divider (Used internally by drivers)
`ClockRate:LongWord;`	Clock rate (Hz)
`ClockPhase:LongWord;`	Clock Phase (eg SPI_CLOCK_PHASE_LOW)
`ClockPolarity:LongWord;`	Clock Polarity (eg SPI_CLOCK_POLARITY_LOW)
`SelectPolarity:LongWord;`	Default Chip Select Polarity (eg SPI_CS_POLARITY_LOW)
`Properties:TSPIProperties;`	Device properties
`ChipSelects:array[0..SPI_CS_MAX] of TSPIChipSelect;`	Chip selects
Internal Properties
`Prev:PSPIDevice;`	Previous entry in SPI table
`Next:PSPIDevice;`	Next entry in SPI table

Public variables

SPI logging

`SPI_DEFAULT_LOG_LEVEL:LongWord = SPI_LOG_LEVEL_DEBUG;`	Minimum level for SPI messages. Only messages with level greater than or equal to this will be printed.

`SPI_LOG_ENABLED:Boolean;`

Function declarations

Initialization functions

procedure SPIInit;

Description: Initialize the SPI unit and SPI device table

Note	Called only during system startup

SPI functions

function SPIDeviceStart(SPI:PSPIDevice; Mode,ClockRate,ClockPhase,ClockPolarity:LongWord):LongWord;

Description: Start the specified SPI device ready for writing and reading

SPI	The SPI device to start
Mode	The device mode to set (eg SPI_MODE_4WIRE)
ClockRate	The clock rate to set for the device
ClockPhase	The clock phase to set (eg SPI_CLOCK_PHASE_LOW)
ClockPolarity	The clock polarity to set (eg SPI_CLOCK_POLARITY_LOW)
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceStop(SPI:PSPIDevice):LongWord;

Description: Stop the specified SPI device and terminate writing and reading

SPI	The SPI device to stop
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceRead(SPI:PSPIDevice; ChipSelect:Word; Dest:Pointer; Size,Flags:LongWord; var Count:LongWord):LongWord;

Description: Read data from the specified SPI device

SPI	The SPI device to read from
ChipSelect	The chip select for the slave to read from (eg SPI_CS_0)
Dest	Pointer to a buffer to receive the data
Size	The size of the buffer
Flags	The flags for this transfer (eg SPI_TRANSFER_DMA)
Count	The number of bytes read on return
Return	ERROR_SUCCESS if completed or another error code on failure
Note	Because SPI writes and then reads for each byte, dummy data will be written for each byte to be read.

function SPIDeviceWrite(SPI:PSPIDevice; ChipSelect:Word; Source:Pointer; Size,Flags:LongWord; var Count:LongWord):LongWord;

Description: Write data to the specified SPI device

SPI	The SPI device to write to
ChipSelect	The chip select for the slave to write to (eg SPI_CS_0)
Source	Pointer to a buffer of data to transmit
Size	The size of the buffer
Flags	The flags for this transfer (eg SPI_TRANSFER_DMA)
Count	The number of bytes written on return
Return	ERROR_SUCCESS if completed or another error code on failure
Note	Because SPI writes and then reads for each byte, received data will be discarded for each by written.

function SPIDeviceWriteRead(SPI:PSPIDevice; ChipSelect:Word; Source,Dest:Pointer; Size,Flags:LongWord; var Count:LongWord):LongWord;

Description: Write data to and Read data from the specified SPI device in one operation

SPI	The SPI device to write to and read from
ChipSelect	The chip select for the slave to write to and read from (eg SPI_CS_0)
Source	Pointer to a buffer of data to transmit
Dest	Pointer to a buffer to receive the data
Size	The size of the buffer
Flags	The flags for this transfer (eg SPI_TRANSFER_DMA)
Count	The number of bytes written and read on return
Return	ERROR_SUCCESS if completed or another error code on failure
Note	Because SPI writes and then reads for each byte, both the source and dest buffers must be the same size.

function SPIDeviceGetMode(SPI:PSPIDevice):LongWord;

Description: Get the device mode of the specified SPI device

SPI	The SPI device to get device mode from
Return	The device mode or SPI_MODE_UNKNOWN on failure

function SPIDeviceSetMode(SPI:PSPIDevice; Mode:LongWord):LongWord;

Description: Set the device mode for the specified SPI device

SPI	The SPI device to set device mode for
Mode	The device mode to set (eg SPI_MODE_4WIRE)
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceGetClockRate(SPI:PSPIDevice; ChipSelect:Word):LongWord;

Description: Get the clock rate of the specified SPI device

SPI	The SPI device to get clock rate from
ChipSelect	The chip select number to get clock rate from (SPI_CS_NONE for default)
Return	The clock rate in Hz or 0 on failure

function SPIDeviceSetClockRate(SPI:PSPIDevice; ChipSelect:Word; ClockRate:LongWord):LongWord;

Description: Set the clock rate for the specified SPI device

SPI	The SPI device to set clock rate for
ChipSelect	The chip select number to set clock rate for (SPI_CS_NONE for default)
ClockRate	The clock rate to set in Hz
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceGetClockPhase(SPI:PSPIDevice):LongWord;

Description: Get the clock phase of the specified SPI device

SPI	The SPI device to get clock phase from
Return	The clock phase or SPI_CLOCK_PHASE_UNKNOWN on failure

function SPIDeviceSetClockPhase(SPI:PSPIDevice; ClockPhase:LongWord):LongWord;

Description: Set the clock phase for the specified SPI device

SPI	The SPI device to set clock phase for
ClockPhase	The clock phase to set (eg SPI_CLOCK_PHASE_LOW)
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceGetClockPolarity(SPI:PSPIDevice):LongWord;

Description: Get the clock polarity of the specified SPI device

SPI	The SPI device to get clock polarity from
Return	The clock polarity or SPI_CLOCK_POLARITY_UNKNOWN on failure

function SPIDeviceSetClockPolarity(SPI:PSPIDevice; ClockPolarity:LongWord):LongWord;

Description: Set the clock polarity for the specified SPI device

SPI	The SPI device to set clock polarity for
ClockPolarity	The clock polarity to set (eg SPI_CLOCK_POLARITY_LOW)
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceGetSelectPolarity(SPI:PSPIDevice; ChipSelect:Word):LongWord;

Description: Get the chip select polarity of the specified SPI device

SPI	The SPI device to get chip select polarity from
ChipSelect	The chip select number to get polarity from (SPI_CS_NONE for default)
Return	The chip select polarity or SPI_CS_POLARITY_UNKNOWN on failure

function SPIDeviceSetSelectPolarity(SPI:PSPIDevice; ChipSelect:Word; SelectPolarity:LongWord):LongWord;

Description: Set the chip select polarity for the specified SPI device

SPI	The SPI device to set chip select polarity for
ChipSelect	The chip select number to set polarity for (SPI_CS_NONE for default)
SelectPolarity	The chip select polarity to set (eg SPI_CS_POLARITY_LOW)
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceGetByteDelay(SPI:PSPIDevice):LongWord;

Description: Get the delay between bytes written for the specified SPI device

SPI	The SPI device to get the byte delay from
Return	The byte delay in microseconds, 0 if not set or on failure

function SPIDeviceSetByteDelay(SPI:PSPIDevice; Delay:LongWord):LongWord;

Description: Set the delay between bytes written for the specified SPI device

SPI	The SPI device to set byte delay for
Delay	The byte delay to set in microseconds
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceProperties(SPI:PSPIDevice; Properties:PSPIProperties):LongWord; inline;

Description: Get the properties for the specified SPI device

SPI	The SPI device to get properties from
Properties	Pointer to a TSPIProperties structure to fill in
Return	ERROR_SUCCESS if completed or another error code on failure
Note	Replaced by SPIDeviceGetProperties for consistency

function SPIDeviceGetProperties(SPI:PSPIDevice;Properties:PSPIProperties):LongWord;

Description: Get the properties for the specified SPI device

SPI	The SPI device to get properties from
Properties	Pointer to a TSPIProperties structure to fill in
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceCreate:PSPIDevice;

Description: Create a new SPI entry

Return	Pointer to new SPI entry or nil if SPI could not be created

function SPIDeviceCreateEx(Size:LongWord):PSPIDevice;

Description: Create a new SPI entry

Size	Size in bytes to allocate for new SPI (Including the SPI entry)
Return	Pointer to new SPI entry or nil if SPI could not be created

function SPIDeviceDestroy(SPI:PSPIDevice):LongWord;

Description: Destroy an existing SPI entry

SPI	The SPI device to destroy
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceRegister(SPI:PSPIDevice):LongWord;

Description: Register a new SPI in the SPI table

SPI	The SPI device to register
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceDeregister(SPI:PSPIDevice):LongWord;

Description: Deregister an SPI from the SPI table

SPI	The SPI device to deregister
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceFind(SPIId:LongWord):PSPIDevice;

Description: ERROR_SUCCESS if completed or another error code on failure

SPIId	The ID number of the SPI device to find
Return	Pointer to SPI device entry or nil if not found

function SPIDeviceFindByName(const Name:String):PSPIDevice; inline;

Description: Find an SPI device by name in the device table

Name	The name of the SPI device to find (eg SPI0)
Return	Pointer to SPI device entry or nil if not found

function SPIDeviceFindByDescription(const Description:String):PSPIDevice; inline;

Description: Find an SPI device by description in the device table

Description	The description of the SPI to find (eg BCM2837 SPI0 Master)
Return	Pointer to SPI device entry or nil if not found

function SPIDeviceEnumerate(Callback:TSPIEnumerate; Data:Pointer):LongWord;

Description: Enumerate all SPI devices in the SPI table

Callback	The callback function to call for each SPI device in the table
Data	A private data pointer to pass to callback for each SPI device in the table
Return	ERROR_SUCCESS if completed or another error code on failure

function SPIDeviceNotification(SPI:PSPIDevice; Callback:TSPINotification; Data:Pointer; Notification,Flags:LongWord):LongWord;

Description: Register a notification for SPI device changes

Device	The SPI device to notify changes for (Optional, pass nil for all SPI devices)
Callback	The function to call when a notification event occurs
Data	A private data pointer to pass to callback when a notification event occurs
Notification	The events to register for notification of (eg DEVICE_NOTIFICATION_REGISTER)
Flags	The flags to control the notification (eg NOTIFIER_FLAG_WORKER)

RTL SPI functions

function SysSPIAvailable:Boolean;

Description: Check if an SPI device is available

Note	None documented

function SysSPIStart(Mode,ClockRate,ClockPhase,ClockPolarity:LongWord):LongWord;

Description: Start the default SPI device ready for writing and reading

Mode	The device mode to set (eg SPI_MODE_4WIRE)
ClockRate	The clock rate to set for the device
ClockPhase	The clock phase to set (eg SPI_CLOCK_PHASE_LOW)
ClockPolarity	The clock polarity to set (eg SPI_CLOCK_POLARITY_LOW)
Return	ERROR_SUCCESS if completed or another error code on failure

function SysSPIStop:LongWord;

Description: Stop the default SPI device and terminate writing and reading

Return	ERROR_SUCCESS if completed or another error code on failure

function SysSPIRead(ChipSelect:Word; Dest:Pointer; Size:LongWord; var Count:LongWord):LongWord;

Description: Read data from the default SPI device

ChipSet	The chip select for the slave to read from (eg SPI_CS_0)
Dest	Pointer to a buffer to receive the data
Size	The size of the buffer
Count	The number of bytes read on return
Return	ERROR_SUCCESS if completed or another error code on failure
Note	Because SPI writes and then reads for each byte, dummy data will be written for each byte to be read.

function SysSPIWrite(ChipSelect:Word; Source:Pointer; Size:LongWord; var Count:LongWord):LongWord;

Description: Write data to the default SPI device

ChipSet	The chip select for the slave to write to (eg SPI_CS_0)
Source	Pointer to a buffer of data to transmit
Size	The size of the buffer
Count	The number of bytes written on return
Return	ERROR_SUCCESS if completed or another error code on failure
Note	Because SPI writes and then reads for each byte, received data will be discarded for each by written.

function SysSPIWriteRead(ChipSelect:Word; Source,Dest:Pointer; Size:LongWord; var Count:LongWord):LongWord;

Description: Write data to and Read data from the default SPI device in one operation

ChipSet	The chip select for the slave to write to and read from (eg SPI_CS_0)
Source	Pointer to a buffer of data to transmit
Dest	Pointer to a buffer to receive the data
Size	The size of the buffer
Count	The number of bytes written and read on return
Return	ERROR_SUCCESS if completed or another error code on failure
Note	Because SPI writes and then reads for each byte, both the source and dest buffers must be the same size.

function SysSPIGetMode:LongWord;

Description: Get the device mode of the default SPI device

Return	The device mode or SPI_MODE_UNKNOWN on failure

function SysSPISetMode(Mode:LongWord):LongWord;

Description: Set the device mode for the default SPI device

Mode	The device mode to set (eg SPI_MODE_4WIRE)
Return	ERROR_SUCCESS if completed or another error code on failure

function SysSPIGetClockRate(ChipSelect:Word):LongWord;

Description: Get the clock rate of the default SPI device

ChipSelect	The chip select number to get clock rate from (SPI_CS_NONE for default)
Return	The clock rate in Hz or 0 on failure

function SysSPISetClockRate(ChipSelect:Word; ClockRate:LongWord):LongWord;

Description: Set the clock rate for the default SPI device

ChipSelect	The chip select number to set clock rate for (SPI_CS_NONE for default)
ClockRate	The clock rate to set in Hz
Return	ERROR_SUCCESS if completed or another error code on failure

function SysSPIGetClockPhase:LongWord;

Description: Get the clock phase of the default SPI device

Return	The clock phase or SPI_CLOCK_PHASE_UNKNOWN on failure

function SysSPISetClockPhase(ClockPhase:LongWord):LongWord;

Description: Set the clock phase for the default SPI device

ClockPhase	The clock phase to set (eg SPI_CLOCK_PHASE_LOW)
Return	ERROR_SUCCESS if completed or another error code on failure

function SysSPIGetClockPolarity:LongWord;

Description: Get the clock polarity of the default SPI device

Return	The clock polarity or SPI_CLOCK_POLARITY_UNKNOWN on failure

function SysSPISetClockPolarity(ClockPolarity:LongWord):LongWord;

Description: Set the clock polarity for the default SPI device

ClockPolarity	The clock polarity to set (eg SPI_CLOCK_POLARITY_LOW)
Return	ERROR_SUCCESS if completed or another error code on failure

function SysSPIGetSelectPolarity(ChipSelect:Word):LongWord;

Description: Get the chip select polarity of the default SPI device

ChipSet	The chip select number to get polarity from (SPI_CS_NONE for default)
Return	The chip select polarity or SPI_CS_POLARITY_UNKNOWN on failure

function SysSPISetSelectPolarity(ChipSelect:Word; SelectPolarity:LongWord):LongWord;

Description: Set the chip select polarity for the default SPI device

ChipSet	The chip select number to set polarity for (SPI_CS_NONE for default)
SelectPolarity	The chip select polarity to set (eg SPI_CS_POLARITY_LOW)
Return	ERROR_SUCCESS if completed or another error code on failure

SPI helper functions

function SPIGetCount:LongWord; inline;

Description: Get the current SPI count

Note	None documented

function SPIDeviceGetDefault:PSPIDevice; inline;

Description: Get the current default SPI device

Note	None documented

function SPIDeviceSetDefault(SPI:PSPIDevice):LongWord;

Description: Set the current default SPI device

Note	None documented

function SPIDeviceCheck(SPI:PSPIDevice):PSPIDevice;

Description: Check if the supplied SPI is in the SPI table

Note	None documented

function SPITypeToString(SPIType:LongWord):String;

Description: Convert an SPI type value to a string

Note	None documented

function SPIStateToString(SPIState:LongWord):String;

Description: Convert an SPI state value to a string

Note	None documented

procedure SPILog(Level:LongWord; SPI:PSPIDevice; const AText:String);