ST7628
Address Counter
The address counter sets the addresses of the display data RAM for writing.
Data is written pixel into the RAM matrix of ST7628. The data for one pixel or two pixels is collected (RGB 5-6-5-bit),
according to the data formats. As soon as this pixel-data information is complete, the “Write access” is activated on the
RAM. The locations of RAM are addressed by the address pointers. The address ranges are X=0 to X=97 (61hex) and Y=0
to Y=69 (45h). Addresses outside these ranges are not allowed.
Before writing to the RAM, a window must be defined into which will be written. The window is programmable via the
command registers XS, YS designating the start address and XE, YE designating the end address.
For example the whole display contents will be written, the window is defined by the following values: XS=0 (0h) YS=0 (0h)
and XE=97 (61h), YE=69 (45h).
In vertical addressing mode (MV=1), the Y-address increments after each byte, after the last Y-address (Y=YE), Y wraps
around to YS and X increments to address the next column. In horizontal addressing mode (MV=0), the X-address
increments after each byte, after the last X-address (X=XE), X wraps around to XS and Y increments to address the next
row. After the every last address (X=XE and Y=YE) the address pointers wrap around to address (X=XS and Y=YS). For
flexibility in handling a wide variety of display architectures, the commands “CASET, RASET” and “MADCTR” (see section
“9.1.31”), define flags MX and MY, which allows mirroring of the X-address and Y-address. All combinations of flags are
allowed. Figure 7.3 show the available combinations of writing to the display RAM. When MX, MY and MV will be changed
the databus be rewritten to the display RAM.
For each image condition, the controls for the column and row counters apply as below:
Condition
Column Counter
Return to “Start
Column (XS)”
Row Counter
Return to “Start
Row (YS)”
When RAMWR command is accepted
Complete Pixel Read / Write action
Increment by 1
No change
The Column counter value is larger than “End Column (XE)”
Return to “Start
Column (XS)”
Increment by 1
The Column counter value is larger than “End Column (XE)” and Return to “Start
the Row counter value is larger than “End Row (YE)” Column (XS)”
Return to “Start
Row (YS)”
Ver 1.4
31/213
2008/08
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
