RA8835A
Version 1.0
Dot Matrix LCD Controller
8. Application Notes
8-1 Initialization Parameters
The parameters for the initialization commands must be determined first. Square brackets around a
parameter name indicate the number represented by the parameter, rather than the value written to the
parameter register. For example, [FX] = FX + 1.
8-1-1 System Set Instruction and Parameters
◎ FX
The horizontal character field size is determined from the horizontal display size in pixels [VD] and the
number of characters per line [VC].
[VD]
≤ [FX]
[VC]
◎ C/R
C/R can be determined from VC and FX.
[FX]
[C/R] = RND(
)×[VC]
8
Where RND(x) denotes ´ rounded up to the next highest integer. [C/R] is the number of bytes per line,
not the number of characters.
◎ TC/R
TC/R must satisfy the condition [TC/R] ≥ [C/R]+ 4 .
◎ fOSC and fFR
Once TC/R has been set, the frame frequency, fFR, and lines per frame [L/F] will also have been set.
The lower limit on the oscillator frequency fOSC is given by:
fOSC ≥ ([TC/R]×9+1)×[L/F]×fFR
◎ If no standard crystal close to the calculated value of fOSC exists, a higher frequency crystal can be
used and the value of TC/R revised using the above equation.
◎ Symptoms of an incorrect TC/R setting are listed below. If any of these appears, check the value of
TC/R and modify it if necessary.
• Vertical scanning halts and a high-contrast horizontal line appears.
• All pixels are on or off.
• The LP output signal is absent or corrupted.
• The display is unstable.
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