Unit SPI

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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.

`SPI_NAME_PREFIX = 'SPI';`	Name prefix for SPI Devices
`SPISLAVE_NAME_PREFIX = 'SPISlave';`	Name prefix for SPI Slave Devices

`SPI_TYPE_NONE = 0;`
`SPI_TYPE_MASTER = 1;`
`SPI_TYPE_SLAVE = 2;`

`SPI_TYPE_MAX = 2;`

SPI Type Names
`SPI_TYPE_NAMES:array[SPI_TYPE_NONE..SPI_TYPE_MAX] of String = ('SPI_TYPE_NONE', 'SPI_TYPE_MASTER', 'SPI_TYPE_SLAVE');`

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

`SPI_STATE_MAX = 1;`

`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_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_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

`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)

`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)

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

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

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

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.

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 byte written.

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.

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

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

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

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

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

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

Unit SPI

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

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

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

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

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

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

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

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

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

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