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MCS_beginExt

Checks to see if DDC/CI communication is available and opens it

Declaration

int NAPI MCS_beginExt(
GA_devCtx *dc,
N_int32 channel)

Prototype In

snap/ddc.h

Parameters

dc | SNAP device driver to use for communications
channel | I2C channel to use to control the monitor (0 for primary monitor)

Return Value

One of the DDC_errCode error return values.

Description

This function initializes the DDC communications module. After checking that the I2C interface is working, this function will attempt to initialize the DDC communication channel and verify that DDC2B communication is possible. If DDC2B is not available, this function returns a value of ddcNoCommunication (ie: cannot communicate with slave). The most likely cause of this failure condition is that there is no DDC capable monitor attached to the graphics device.

Once DDC2B functionality has been detected, this function attempts to read the capabilities string from the monitor using the DDC/CI protocol. If a DDC/CI compatible monitor is successfully found, this function returns ddcOk. If the capabilities string could not be read, this function returns ddcNotAvailable, which generally indicates that the attached monitor is not DDC/CI capable. This function also parses the monitor capabilities string to determine what features the monitor supports and initializes the device driver accordingly.

Note: After you have finished with communications over the DDC/CI interface, you must call MCS_end to close the communications channel.

See Also

MCS_end

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