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Setting/Acquisition LCD Contrast
The contrast of the LCD display is affected and varied by the ambient temperature. Therefore,
this terminal automatically detects the variation of ambient temperature and determines an optimal
contrast based on the acquired data. However, it may not immediately react to rapid temperature
variations or be ideal for each specific user. With this in mind, the terminal is provided with a means
to increase or decrease the LCD contrast manually.
The contrast value returned by this function is a correction value to the optimum contrast that has
been determined by automatic calculation. The value returned will be zero if no correction is made
manually; +1 or -1 will be returned if the contrast is increased or decreased by one step, respectively.
The range of contrast values that can be set or read varies according to the ambient temperature.
This is because the range of setup values that can be set for the hardware is between 0 and 31. If, for
example, the automatically calculated value is 10, the possible correction range is between - 10 and
+21. Consequently, the range of contrast values that can be read or set is between - 31 and +31.
The practical use of this library function lies in saving or loading the contrast setup prior to using the
SYS_LcdContrastUp() or SYS_LcdContrastDown() function.
SYNTAX
int SYS_GetLcdContrast(int WINFAR *nValue);
INPUT
nValue = Pointer to the area where the current correction value is acquired.
OUTPUT
= 0 Normal
= -2 No response from KBC
= -3 VxD not registered
SYNTAX
int SYS_SetLcdContrast(int nValue);
INPUT
nValue = Correction value to be set
OUTPUT
= 0 Normal
= -2 No response from KBC
= -3 VxD not registered
