Page 32 Epson Research and Development
Vancouver Design Center
S1D13505 Programming Notes and Examples
X23A-G-003-07 Issue Date: 01/02/05
Both panning and scrolling are performed by modifying the start address register. The st art
address refers to the word offset in the display buffer where the image will start being
displayed from. At color depths less than 15 bpp a second register, the pixel pan register, is
required for smooth pixel level panning.
Internally, the S1D13505 latches different signals at different times. Due to this internal
sequence, there is an order in which the start address and pixel pan registers should be
accessed during scrolling operations to provide the smoothest scrolling. Setting the
registers in the wrong sequence or at the wrong time will resul t in a “t earing” or jitter ef fect
on the display.
The start address is latched at the begin ni ng of each frame, therefore the start addr ess can
be set any time during the display period. The pixel pan register values are latched at the
beginning of each display line and must be set during the vertical non-display period. The
correct sequence for programing these registers is:
1. Wait until just after a vertical non-display period (read register [0Ah] and watch bit 7
for the non-display status).
2. Update the start address registers.
3. Wait until the next vertical non-display period.
4. Update the pixel paning register.
5.2.1 Registers
Figure 5-3: Screen 1 Start Address Registers
These three registers form the addres s of the word in the display buffer whe re screen 1 will
start displaying from. Changing these registers by one will cause a change o f 0 to 1 6 pixels
depending on the current color depth. Refer to the following table to see the minimum
number of pixels affected by a change of one to these registers.
REG[10h] Screen 1 Display Start Address 0
Start Addr
Bit 7 Start Addr
Bit 6 Start Addr
Bit 5 Start Addr
Bit 4 Start Addr
Bit 3 Start Addr
Bit 2 Start Addr
Bit 1 Start Addr
Bit 0
REG[11h] Screen 1 Display Start Address 1
Start Addr
Bit 15 Start Addr
Bit 14 Start Addr
Bit 13 Start Addr
Bit 12 Start Addr
Bit 11 Start Addr
Bit 10 Start Addr
Bit 9 Start Addr
Bit 8
REG[12h] Screen 1 Display Start Address 2
n/a n/a n/a n/a Start Addr
Bit 19 Start Addr
Bit 18 Start Addr
Bit 17 Start Addr
Bit 16