S1D13704 Epson Electronics America, Inc., S1D13704 Datasheet - Page 106

• Manufacturer Part Number: S1D13704
• Description: LCD Controller
• Manufacturer: Epson Electronics America, Inc.

Page 10
S1D13704
X26A-G-002-03
for (int loop = 0; loop < 2; loop++)
{
}
// If we still can't hit the frame rate - throw an error.
if ((VNDP < 0) || (VNDP > 0x3F) || (HNDP < 32) || (HNDP > 280))
{
}
for (VNDP = 2; VNDP < 0x3F; VNDP += 3)
{
}
// Divide ClkI and try again.
// (Reg[02] allows us to dived CLKI by 2)
PCLK /= 2;
sprintf("ERROR: Unable to set the desired frame rate.\n");
exit(1);
This routine first performs a formula rearrangement so that HNDP or VNDP can be solved
for. Start with VNDP set to a small value. Loop increasing VNDP and solving the equation
for HNDP until satisfactory HNDP and VNDP values are found. If no satisfactory values
are found then divide CLKI and repeat the process. If a satisfactory frame rate still can’t be
reached - return an error.
In C the code looks like the following snip:
// Solve for HNDP
if ((HNDP >= 32) && (HNDP <= 280))
{
}
HNDP = (PCLK / (FrameRate * (VDP + VNDP))) - HDP;
// Solve for VNDP.
VNDP = (PCLK / (FrameRate * (HDP + HNDP))) - VDP;
// If we have satisfied VNDP then we're done.
if ((VNDP >= 0) && (VNDP <= 0x3F))
goto DoneCalc;
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Programming Notes and Examples
Vancouver Design Center
Issue Date: 01/02/12