PEDL9041A-02
OKI Semiconductor
ML9041A-xxA/xxB
2) Large character patterns (5 × 11 dots) (See Table 3-2.)
(1) A method of writing character patterns to the CGRAM from the CPU
The four CGRAM address bit weights 0 to 3 select one of the lines constituting a character pattern.
First, set the mode to increment or decrement from the CPU, and then input the CGRAM address.
Write each line of the character pattern code in the CGRAM through DB0 to DB7.
The data lines DB0 to DB7 correspond to the CGRAM data bit weights 0 to 7, respectively (see Table 3-
2). Input data “1” represents the ON status of an LCD dot and “0” represents the OFF status. Since the
ADC is automatically incremented or decremented by 1 after the data is written to the CGRAM, it is not
necessary to set the CGRAM address again.
The bottom line of a character pattern (the CGRAM address bit weights 0 to 3 are all “1”, which means A
in hexadecimal) is a cursor line. The ON/OFF pattern of this line is ORed with the cursor pattern for
displaying on the LCD. Therefore, the pattern data for the cursor position should be all zeros to display
the cursor.
Whereas CGRAM data bit weights 0 to 4 are output as display data to the LCD when CGRAM address bit
weights 0 to 3 are “0” to “A” in hexadecimal, the data given by the CGRAM data bit weights 5 to 7 or the
CGRAM addresses B to F in hexadecimal is not. These bits can be written and read as a RAM area.
(2) A method of displaying CGRAM character patterns on the LCD
The CGRAM is selected when the higher-order 4 bits of a character code are all zeros. Since bit weights
0 and 3 of a character code are not used, the character pattern “g” in Table 3-2 can be selected with a
character code “02”, “03”, “0A” or “0B” in hexadecimal.
When the 8-bit character code corresponding to a character pattern in the CGRAM is written to the
DDRAM, the character pattern is displayed in the display position specified by the DDRAM address.
(The DDRAM data bit weights 1 and 2 correspond to the CGRAM address bit weights 4 and 5,
respectively.)
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