ST7920
Graphic RAM (GDRAM)
Graphic Display RAM has 64x256 bits bit-mapped memory space. GDRAM address is set by writing 2 consecutive
bytes of vertical address and horizontal address. Two-byte data (16 bits) configures one GDRAM horizontal address.
The Address Counter (AC) will be increased by one automatically after receiving the 16-bit data for the next operation.
After the horizontal address reaching 0FH, the horizontal address will be set to 00H and the vertical address will not
change. The procedure is summarized below:
1. Set vertical address (Y) for GDRAM
2. Set horizontal address (X) for GDRAM
3. Write D15~D8 to GDRAM (first byte)
4. Write D7~D0 to GDRAM (second byte)
Please refer to Table 7 for Graphic Display RAM mapping.
LCD driver
ST7920 embedded LCD driver has 33 commons and 64 segments to drive the LCD panel. Segment data from
CGRAM, CGROM and HCGROM are shifted into the 64 bits segment latche to display. Extended segment driver
(ST7921) can be used to extend the segment outputs upto 256 segments.
V4.0
12/49
2008/08/18
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
