Phytec eGrabber-4plus, Hardware Manual

Page: 157 / 206

Driver Software

PHYTEC Meßtechnik GmbH 2004 L-608e_4
147
BYTE I2C_ReadByte (WORD nDevNo, BYTE bChipAddress,
BYTE bSubAddress, BYTE *bByteRead)
bChipAddress: Device address for the I²C device on the bus
bSubAddress: Internal memory address for the I²C device
*bByteRead:
Pointer points to a Byte variable. Result
is written into the Byte variable.
return value: SUCCESS, NOACK, INVALID_ADDRESS
I2C_ReadByte is used to read a Byte from the memory space of an I²C
device. The result is given in a variable Byte type. This Byte must be
defined before hand.
The function returns an error code as a return value.
NOACK
indicates
that no I²C device has been registered under the given device address.
INVALID_ADDRESS
indicates an unsuccessful attempt to access the
protected area of the EEPROM mounted on the Grabber.
BYTE I2C_WriteByte (WORD nDevNo, BYTE b ChipAddress,
BYTE bSubAddress, BYTE bData)
bChipAddress: Device address of the
I²C device on the bus
bSubAddress: Internal memory address of the
I²C device
bData: Byte written into the specified address
return value: SUCCESS, NOACK, INVALID_ADDRESS,
WRITE_FAILED
Writes a Byte into the memory space of a specified I²C device.
The function returns an error code as a return value.
Note:
The internal processing time of some devices (EEPROMs for
example) might be noticable longer than the I²C-bus cycle time. If
several write cycles are sent to such a device, this might result in a
NOACK
-error, since the device is not yet ready to process the next write
cycle.
To avoid this, read commands should be executed after a write cycle,
until the written value is returned. After that, the device is ready to
process a new write cylce. Please refer also to the data sheet of the
I²C-device used.