MCP2200
2.3.1.21
Function:
ReadPortValue
int SimpleIOClass::ReadPortValue()
Summary:
Reads the GPIO port as digital input.
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.
Description:
Precondition: Must be previously configured as an input via a ConfigureIOcall.
VID and PID must be previously set via a call to InitMCP2200(VID, PID).
Parameters:
Returns:
None.
This function returns True if the transmission is successful and returns False if the transmission fails.
Pins configured for output return the current state of the port. Pins configured as input read as zero.
Remarks:
EXAMPLE 2-21:
int rv;
rv = SimpleIOClass::ReadPortValue()
if (rv != 0x8000)
{
lblStatusBar->Text = “Success”;
}
else
lblStatusBar->Text = “Invalid command ” + SimpleIOClass::LastError;
2.3.1.22
Function:
SelectDevice
int SimpleIOClass::SelectDevice(unsigned int uiDeviceNo)
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.
EXAMPLE 2-22:
int iResult;
iResult = SimpleIOClass::SelectDevice(1)
if (iResult == 0)
{
lblStatusBar->Text = “Success”;
}
else
lblStatusBar->Text = “Error selecting device”;
2011 Microchip Technology Inc.
DS22228B-page 21
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