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Resuming the Display
ReadGPIO
BOOL APIENTRY ReadGPIO
Purpose
Reads the state of an entire GPIO (all four GPIO lines).
Input
[out] PBYTE pValue - pointer to the byte variable in which to
place the read value of the GPIO state. The returned value will be
placed into the four least significant bits of this variable; the four
most significant bits are unused.
[in] BYTE status - the byte value for four-direction (input/
output) bits of GPIO register. For each of these bits, the value 0
means input (reading from GPIO line) and the value 1 means
output (writing to GPIO line). For each ReadGPIO operation the
status bits can be set to the required direction. (For example, the
value 0x3 indicates that GPIO lines 0 and 1 will be set to output
and GPIO lines 2 and 3 will be set to input.) Legal values for this
parameter are 0-15.
Output
The value level of all four lines.
Returned Value BOOL value: TRUE - success, FALSE - failure
WriteGPIO
BOOL APIENTRY WriteGPIO
Purpose
Sets the state of an entire GPIO (all four GPIO lines).
Input
[in] BYTE Value - the byte value that indicates a new state for
the GPIO. Legal values for this parameter are 0-15.
Output
None
Returned Value BOOL value: TRUE - success, FALSE - failure
This section describes how to interrupt the screen saver or activate the display in
the event that an emergency message is received. The message is then displayed
on screen.
The following instructions use the API function
terminate the screen saver. An MSDN-recommended practice is described in the
technical articles Q140723 and Q150785.
VOID keybd_event(BYTE, BYTE, DWORD, ULONG_PTR)
The
function emulates a keystroke. It can be used to generate a
keybd_event
or
WM_KEYUP
WM_KEYDOWN
Windows, thereby terminating the screen saver.
Using Specific Hardware Features
(PBYTE pValue, BYTE status)
(BYTE Value)
keybd_event()
message, which imitates key pressing/releasing for
39
to artificially
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