MCP2200_13 datasheet(21/44 Pages) MICROCHIP

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 2011 Microchip Technology Inc.

DS22228B-page 21

MCP2200

2.3.1.21

ReadPortValue

Function:

int SimpleIOClass::ReadPortValue()

EXAMPLE 2-21:

2.3.1.22

SelectDevice

Function:

int SimpleIOClass::SelectDevice(unsigned int uiDeviceNo)

EXAMPLE 2-22:

Summary:

Reads the GPIO port as digital input.

Description:

Reads the GPIO port and returns the value of the port. This provides a method to read all pins

simultaneously, instead of one-by-one. In case of an error, the returned value will be 0x8000.

Precondition:

Must be previously configured as an input via a ConfigureIO call.

VID and PID must be previously set via a call to InitMCP2200(VID, PID).

Parameters:

None.

Returns:

This function returns True if the transmission is successful and returns False if the transmission fails.

Remarks:

Pins configured for output return the current state of the port. Pins configured as input read as zero.

Summary:

Selects one of the active devices in the system.

Description:

The function is used to select one of the detected devices in the system as the “active device”.

Precondition:

At least one call to the InitMCP2200() is required in order to initiate a DLL search for the compatible

devices. Also, in order to know the actual number of devices in the system, call the

SimpleIOClass::IsConnected()

function. VID and PID must be previously set via a call to

InitMCP2200(VID, PID)

Parameters:

uiDeviceNo

- the ID of the device to be selected (can have a value between 0 and the number of

devices minus 1).

Returns:

This function returns ‘0’ in case of selection success, otherwise it will return:

• E_WRONG_DEVICE_ID (-1) for a device ID that is out of range

• E_INACTIVE_DEVICE (-2) for an inactive device.

Remarks:

Call the SimpleIOClass::IsConnected() prior to the call of this function in order to have the most

recent number of devices that are present in the system.

int rv;

rv = SimpleIOClass::ReadPortValue()

if (rv != 0x8000)

{

lblStatusBar->Text = “Success”;

}

else

lblStatusBar->Text = “Invalid command ” +

SimpleIOClass::LastError;

int iResult;

iResult = SimpleIOClass::SelectDevice(1)

if (iResult == 0)

{

lblStatusBar->Text = “Success”;

}

else

lblStatusBar->Text = “Error selecting device”;

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