M30222 Datasheet, PDF (146/237 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

deUvnedloepr ^ment
Specifications in this manual are tentative and subject to change
MITSUBISHI MICROCOMPUTERS
M30222 Group
Rev. G
LCD Drive Control Circuit
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
LCD Drive Control Circuit
The M30222 group has the built-in Liquid Crystal Display (LCD) drive control circuit consisting of the
following.
• LCD display RAM
• Segment output enable register
• LCD mode register
• Voltage multiplier
• Selector
• Timing controller
• Common driver
• Segment driver
• Bias control circuit
A maximum of 40 segment output pins and 4 common output pins can be used. This allows up to 160
LCD pixels to be controlled. If static drive is enabled, up to 14 of the 40 multiplexed segment
pins can be assigned to static drive.
The LCD drive control circuit automatically reads the LCD display ram, performs bias and duty ratio
control, and displays the data on the LCD panel. The circuit is configured by writing to the LCD mode
register, the segment output enable register, the LCD display ram, the LCD frame frequency counter,
the LCD expansion register, and the LCD clock divided register. After all these registers are written
then the LCD is turned on by setting the LCD enable bit to "1".
The LCDRAM output function allows the LCD segment output pins to be used as a general purpose
output pin. This mode is configured by writing to the segment output register to enable the segment
function, writing a "00" to the time division select bit and "0" to LCD output enable bit, and setting the
LCDRAM output enable bit to "1". The data that is written to the LCDRAM bit 4 or 0 will be output on its
corresponding segment pin. Note that in this mode VL3 & VL2 must be connected to VDD and VL1
must be connected to VSS.
Table 1.45 shows the maximum number of display pixels at each duty ratio.
Figure 1.117 shows the block diagram of LCD controller / driver. Figures 1.118 and 1.119 show the
LCD-related registers.
Table 1.45. Maximum number of display pixels at each duty ratio
Duty ratio ^{Maximum number of display pixels}
(multiplexed)
2
80 dots or 8 segment LCD 10 digits
3
120 dots or 8 segment LCD 15 digits
4
160 dots or 8 segment LCD 20 digits
Static drive
OFF
OFF
OFF
1-147