NEC uPD72257, Preliminary User'S Manual

Page: 195 / 343

VOnHSYNC The diagram below illustrates the line synchronization timing settings.
The video data enable signal VOnEN is derived from the other timing values:
VOnEN width in pixels = pixels/line - horizontal (front porch + back porch + sync
pulse width)
The active level of the VOnHSYNC and VOnEN signals can be defined as follows:
• active level of VOnHSYNC
-
VOnLCDTIMING2.IHS = 0: VOnHSYNC is active high
- VOnLCDTIMING2.IHS = 1: VOnHSYNC is active low
• active level of VOnEN
-
VOnLCDTIMING2.IOE = 0: VOnEN is active high
- VOnLCDTIMING2.IOE = 1: VOnEN is active low
HSW HBP
VOnHSYNC
IHS = 0
VOnHSYNC
IHS = 1
VOnEN
IOE = 0
HFP
PPL
Video data valid
VOnEN
IOE = 1
Figure 7-3 VOnHSYNC timing setting
VOnVSYNC The diagram below illustrates the line synchronization timing settings.
The active level of the VOnVSYNC signal can be defined as follows:
• active level of VOnVSYNC
-
VOnLCDTIMING2.IVS = 0: VOnVSYNC is active high
- VOnLCDTIMING2.IVS = 1: VOnVSYNC is active low
The point in time to generate the vertical compare interrupt VOnVCPINT, that
indicates the start of a new frame, can be chosen as follows:
• VOnVCPINT interrupt timing
-
VOnLCDCONTROL.LCDVCOMP[1:0] = 00
B
: at start of the
HSYNC pulse
- VOnLCDCONTROL.LCDVCOMP[1:0] = 01
B
: at start of the back
porch
- VOnLCDCONTROL.LCDVCOMP[1:0] = 10
B
: at start of the
active video data
- VOnLCDCONTROL.LCDVCOMP[1:0] = 11
B
: at start of the front
porch
Video Output Chapter 7
Preliminary User's Manual S19203EE1V3UM00
195