Cirrus Logic AN269 - Manual (Page 61)

AN269
AN269REV1 61
Next, the Horizontal Synchronization Signals can be determined, using the following equations:
HClkTotal = tHORIZ - 1
HClkTotal = 90 - 1 = 89 (SPCLK periods)
Therefore:
HSyncStart = HClkTotal
HSyncStart = 89
HSyncStop = HClkTotal - tHSYNC
HSyncStop = 89 - 1 = 88
HBlankStart = HClkTotal - tHSYNC - tHFRONTPORCH - 1= 89 - 1 - 2 - 1 = 85
HBlankStop = HClkTotal - tHSYNC - tHFRONTPORCH - tActive - 1 = 89 - 1 - 2 - 80 - 1= 5
HActiveStart = HBlankStart = 85
HActiveStop = HBlankStop = 5
HClkStart = HClkTotal - tHSYNC - tHFRONTPORCH - 6 = 89 - 1 - 2 - 6 = 80
HClkStop = HClkTotal - tHSYNC - tHFRONTPORCH - tActive - 1 = 89 - 1 - 2 - 80 - 6 = 0
Now, the vertical timing register settings can be determined. Using the equations from "Vertical Alignment Signals",
the following values are obtained:
VLinesTotal = Tvert
VLinesTotal = 240
VSyncStart = VLinesTotal -1 = 239
VSyncStop = VSyncStart -1 = 238
VBlankStart = 0
VBlankStop = 0
VActiveStart =239
VActiveStop =240
Again, we can set VClkStart and VClkStop to VLinesTotal:
VClkStart = VClkStop = VLinesTotal = 240