Unit I2C
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Description
I2C (Inter-Integrated Circuit) is a serial bus for communication between peripheral components.
Originally invented by Phillips the I2C protocol is used by thousands of common chips that perform a wide range of tasks such as real time clocks, temperature and other sensors, small LCD displays and many more.
Each device is assigned a 7bit address which is used by the host (or master) to signal the device that a message written to the bus is intended for that device or that the host wants to read data from that device.
Speeds range from 10Kbps to 3.4Mbps although the typical speed is either 100Kbps or 400Kbps.
This unit implements the standardized interface for I2C devices and allows reading or writing to a specific address, setting a clock rate for the communication and determining device properties.
For the purpose of this interface a device is the I2C 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 I2C device should know (or allow configuration of) the address to read and write to and the specific message format required for that device. The Intel System Management Bus (SMBus) is a variation of the I2C bus and in certain cases the two are compatible with each other.
Constants
To be documented
Type definitions
To be documented
Public variables
To be documented
Function declarations
Initialization functions
procedure I2CInit;
Description: Initialize the I2C unit and I2C device table
| Note | Called only during system startup |
|---|
I2C functions
function I2CDeviceStart(I2C:PI2CDevice; Rate:LongWord):LongWord;
Description: Start the specified I2C device ready for reading and writing
| I2C | The I2C device to start |
|---|---|
| Rate | The clock rate to set for the device (0 to use the default rate |
| Return | ERROR_SUCCESS if completed or another error code on failure |
function I2CDeviceStop(I2C:PI2CDevice):LongWord;
Description: Stop the specified I2C device and terminate reading and writing
| I2C | The I2C device to stop |
|---|---|
| Return | ERROR_SUCCESS if completed or another error code on failure |
function I2CDeviceRead(I2C:PI2CDevice; Address:Word; Buffer:Pointer; Size:LongWord; var Count:LongWord):LongWord;
Description: Read data from the specified I2C device
| I2C | The I2C device to read from |
|---|---|
| Address | The slave address to read from (I2C_ADDRESS_INVALID to use the current address) |
| Buffer | 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 |
function I2CDeviceWrite(I2C:PI2CDevice; Address:Word; Buffer:Pointer; Size:LongWord; var Count:LongWord):LongWord;
Description: Write data to the specified I2C device
| I2C | The I2C device to write to |
|---|---|
| Address | The slave address to write to (I2C_ADDRESS_INVALID to use the current address) |
| Buffer | 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 |
function I2CDeviceWriteRead(I2C:PI2CDevice; Address:Word; Initial:Pointer; Len:LongWord; Data:Pointer; Size:LongWord; var Count:LongWord):LongWord;
Description: Write data to and Read data from the specified I2C device in one operation. Useful for devices that require a register address specified before a read (eg EEPROM devices)
| I2C | The I2C device to write to and read from |
|---|---|
| Address | The slave address to write to (I2C_ADDRESS_INVALID to use the current address) |
| Initial | Pointer to the initial buffer to transmit |
| Len | The size of the initial buffer |
| Data | Pointer to a buffer to receive the data |
| Size | The size of the data buffer |
| Count | The number of bytes read on return |
| Return | ERROR_SUCCESS if completed or another error code on failure |
function I2CDeviceWriteWrite(I2C:PI2CDevice; Address:Word; Initial:Pointer; Len:LongWord; Data:Pointer; Size:LongWord; var Count:LongWord):LongWord;
Description: Write 2 data blocks to the specified I2C device in one operation. Useful for devices that require a register address specified before a write (eg EEPROM devices)
| I2C | The I2C device to write to |
|---|---|
| Address | The slave address to write to (I2C_ADDRESS_INVALID to use the current address) |
| Initial | Pointer to the initial buffer to transmit |
| Len | The size of the initial buffer |
| Data | Pointer to a buffer of data to transmit |
| Size | The size of the data buffer |
| Count | The number of bytes of data written on return |
| Return | ERROR_SUCCESS if completed or another error code on failure |
function I2CDeviceGetRate(I2C:PI2CDevice):LongWord;
Description: Get the clock rate of the specified I2C device
| I2C | The I2C device to get the clock rate from |
|---|---|
| Return | The clock rate in Hz or 0 on failure |
function I2CDeviceSetRate(I2C:PI2CDevice; Rate:LongWord):LongWord;
Description: Set the clock rate for the specified I2C device
| I2C | The I2C device to set the clock rate for |
|---|---|
| Rate | The clock rate to set in Hz |
| Return | ERROR_SUCCESS if completed or another error code on failure |
function I2CDeviceGetAddress(I2C:PI2CDevice):Word;
Description: Get the slave address for the specified I2C device
| I2C | The I2C device to get the slave address from |
|---|---|
| Return | The slave address or I2C_ADDRESS_INVALID on failure |
function I2CDeviceSetAddress(I2C:PI2CDevice; Address:Word):LongWord;
Description: Set the slave address for the specified I2C device
| I2C | The I2C device to set the slave address for |
|---|---|
| Address | The slave address to set |
| Return | ERROR_SUCCESS if completed or another error code on failure |
function I2CDeviceProperties(I2C:PI2CDevice; Properties:PI2CProperties):LongWord;
Description: Get the properties for the specified I2C device
| I2C | The I2C device to get properties from |
|---|---|
| Properties | Pointer to a TI2CProperties structure to fill in |
| Return | ERROR_SUCCESS if completed or another error code on failure |
function I2CDeviceCreate:PI2CDevice;
Description: Create a new I2C entry
| Return | Pointer to new I2C entry or nil if I2C could not be created |
|---|
function I2CDeviceCreateEx(Size:LongWord):PI2CDevice;
Description: Create a new I2C entry
| Size | Size in bytes to allocate for new I2C (Including the I2C entry) |
|---|---|
| Return | Pointer to new I2C entry or nil if I2C could not be created |
function I2CDeviceDestroy(I2C:PI2CDevice):LongWord;
Description: Destroy an existing I2C entry
| Note | None documented |
|---|
function I2CDeviceRegister(I2C:PI2CDevice):LongWord;
Description: Register a new I2C in the I2C table
| Note | None documented |
|---|
function I2CDeviceDeregister(I2C:PI2CDevice):LongWord;
Description: Deregister a I2C from the I2C table
| Note | None documented |
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function I2CDeviceFind(I2CId:LongWord):PI2CDevice;
Description: To be documented
| Note | None documented |
|---|
function I2CDeviceFindByName(const Name:String):PI2CDevice; inline;
Description: To be documented
| Note | None documented |
|---|
function I2CDeviceFindByDescription(const Description:String):PI2CDevice; inline;
Description: To be documented
| Note | None documented |
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function I2CDeviceEnumerate(Callback:TI2CEnumerate; Data:Pointer):LongWord;
Description: To be documented
| Note | None documented |
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function I2CDeviceNotification(I2C:PI2CDevice; Callback:TI2CNotification; Data:Pointer; Notification,Flags:LongWord):LongWord;
Description: To be documented
| Note | None documented |
|---|
RTL I2C functions
function SysI2CAvailable:Boolean;
Description: Check if an I2C device is available
| Note | None documented |
|---|
function SysI2CStart(Rate:LongWord):LongWord;
Description: Start the default I2C device ready for reading and writing
| Rate | The clock rate to set for the device (0 to use the default rate) |
|---|---|
| Return | ERROR_SUCCESS if completed or another error code on failure |
function SysI2CStop:LongWord;
Description: Stop the default I2C device and terminate reading and writing
| Return | ERROR_SUCCESS if completed or another error code on failure |
|---|
function SysI2CRead(Address:Word; Buffer:Pointer; Size:LongWord; var Count:LongWord):LongWord;
Description: Read data from the default I2C device
| Address | The slave address to read from (I2C_ADDRESS_INVALID to use the current address) |
|---|---|
| Buffer | 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 |
function SysI2CWrite(Address:Word; Buffer:Pointer; Size:LongWord; var Count:LongWord):LongWord;
Description: Write data to the default I2C device
| Address | The slave address to write to (I2C_ADDRESS_INVALID to use the current address) |
|---|---|
| Buffer | 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 |
function SysI2CWriteRead(Address:Word; Initial:Pointer; Len:LongWord; Data:Pointer; Size:LongWord; var Count:LongWord):LongWord;
Description: Write data to and Read data from the default I2C device in one operation. Useful for devices that require a register address specified before a read (eg EEPROM devices)
| Address | The slave address to write to (I2C_ADDRESS_INVALID to use the current address) |
|---|---|
| Initial | Pointer to the initial buffer to transmit |
| Len | The size of the initial buffer |
| Data | Pointer to a buffer to receive the data |
| Size | The size of the data buffer |
| Count | The number of bytes read on return |
| Return | ERROR_SUCCESS if completed or another error code on failure |
function SysI2CWriteWrite(Address:Word; Initial:Pointer; Len:LongWord; Data:Pointer; Size:LongWord; var Count:LongWord):LongWord;
Description: Write 2 data blocks to the default I2C device in one operation. Useful for devices that require a register address specified before a write (eg EEPROM devices)
| Address | The slave address to write to (I2C_ADDRESS_INVALID to use the current address) |
|---|---|
| Initial | Pointer to the initial buffer to transmit |
| Len | The size of the initial buffer |
| Data | Pointer to a buffer of data to transmit |
| Size | The size of the data buffer |
| Count | The number of bytes of data written on return |
| Return | ERROR_SUCCESS if completed or another error code on failure |
function SysI2CGetRate:LongWord;
Description: Get the clock rate of the default I2C device
| Return | The clock rate in Hz or 0 on failure |
|---|
function SysI2CSetRate(Rate:LongWord):LongWord;
Description: Set the clock rate for the default I2C device
| Rate | The clock rate to set in Hz |
|---|---|
| Return | ERROR_SUCCESS if completed or another error code on failure |
function SysI2CGetAddress:Word;
Description: Get the slave address for the default I2C device
| Return | The slave address or I2C_ADDRESS_INVALID on failure |
|---|
function SysI2CSetAddress(Address:Word):LongWord;
Description: Set the slave address for the default I2C device
| Address | The slave address to set |
|---|---|
| Return | ERROR_SUCCESS if completed or another error code on failure |
I2C helper functions
function I2CGetCount:LongWord; inline;
Description: Get the current I2C count
| Note | None documented |
|---|
function I2CDeviceGetDefault:PI2CDevice; inline;
Description: Get the current default I2C device
| Note | None documented |
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function I2CDeviceSetDefault(I2C:PI2CDevice):LongWord;
Description: Set the current default I2C device
| Note | None documented |
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function I2CDeviceCheck(I2C:PI2CDevice):PI2CDevice;
Description: Check if the supplied I2C is in the I2C table
| Note | None documented |
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procedure I2CLog(Level:LongWord; I2C:PI2CDevice; const AText:String);
Description: To be documented
| Note | None documented |
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procedure I2CLogInfo(I2C:PI2CDevice; const AText:String); inline;
Description: To be documented
| Note | None documented |
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procedure I2CLogError(I2C:PI2CDevice; const AText:String); inline;
Description: To be documented
| Note | None documented |
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procedure I2CLogDebug(I2C:PI2CDevice; const AText:String); inline;
Description: To be documented
| Note | None documented |
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