ViewSonic VG150B Service Manual - Page 26

ViewSonic April 1999 - Version 1.0 THEORY OF CIRCUIT OPERATION Service Manual VG150 Symbol Width (bits) Offset factor CE 8 Offset factor CO 8 Offset factor NE 8 Offset factor NO 8 Scale factor V 8 Minimum pixels per 11 line for LCD LCD polarity 4 Check sum 8 Address 141H 142H 143H 144H 145H 147H-148H 149H[3:0] 14AH Description Offset factor used when generator look up table for current even pixel multiplication Offset factor used when generator look up table for current odd pixel multiplication Offset factor used when generate look up table for next even pixel multiplication Offset factor used when generate look up table for next odd pixel multiplication Scale factor used when generate look up table for line multiplication Minimum number of pixels per line for LCD panel Controls the polarity of output VSYNV, HSYNC, clock and display enable Bit 0:0: clock active high, 1: clock active low Bit 1: 0: HSYNC active low, 1: HSYNC active high Bit 2: 0: VSYNC active low, 1: VSYNC active high Bit 4: 0: de active high, 1: de active low Sum of all part 9 bytes (keep only lower 8 bit) Horizontal Interpolation Lookup Table Symbol Mapped value Check sum Width(bits) 8 8 Address IC0H-2BFH Description This is the base table for all four horizontal interpolation lookup tables. Each table is then generated by multiply this value With corresponding scale factor and added with corresponding offset factor. Sum of all part 10 entry (only keep lower 8 bits) Vertical Interpolation Lookup Table Symbol Mapped value Check sum Width(bits) 8 8 Address 2E0H-3DFH 3E0H Description This is the table for vertical interpolation lookup table. The vertical interpolation table is then generated by multiply this value with vertical scale factor and added with vertical offset factor Sum of all part 10 entry (only keep lower 8 bits) Page 23