
MMC2001DDRM/D
MOTOROLA
Reference Manual
111
Section 9 LCD_A Level 1
This section describes the functions of an LCD_A level 1 device driver.
9.1 Overview
The KS0066U character type dot matrix liquid crystal display (LCD) controller
device and its accompanying device driver (LCD_A) reside on the MMCMPFB1200
platform board (PFB). The MMCMPFB1200 is a development system for the
MMC2001. Level 1 service is designed to allow the programmer to deal with the
KS0066U on a near-register level, but without concern for exact positions of
registers and fields, or detailed sequences of register operations.
KS0066U registers are directly memory addressable from the perspective of the
MCU. The KS0066U is wired to the LCD peripheral and provides the electrical
signaling required for the imaging of a set of characters. The KS0066U does not
generate interrupts. It is necessary to query the part before issuing commands,
reads, or writes to ensure that it is not in a busy state.
The KS0066U has various selectable display modes for which the LCD_A driver
will provide access. It is cursor-oriented in the sense that there is a visible or
invisible cursor position within the display window. The cursor position determines
where the next character will be written. The cursor can be moved to a specific
location within the display window. The cursor can either advance, decrement, or
remain in place after a character is written to a position. The display can be shifted
left or right by one position. The display can be programmed to shift left or right as
each character is written. If two lines are being displayed, both lines are shifted.
The KS0066U contains an internal ROM-based character set with 208 5 x 8 dot
character patterns and 32 5 x 10 dot character patterns. The character set includes
the standard alphanumerics. The numeric values of the characters follows the
standard ASCII convention. These values are used as zero-based offsets into
character generator read-only memory (CGROM). A character is displayed by
writing its corresponding character generator random access memory (CGRAM)
address to the KS0066U, which then copies the bitmap at that position into display
data random access memory (DDRAM) at a position corresponding to the current
location of the cursor.
The first character stored in the CGROM is the “space” character at offset 0x20.
The KS0066U allows the programmer to store up to eight custom character bitmap
patterns in internal RAM at offsets 0x0 through 0x7 which would normally
correspond to ASCII non-printing control characters. The contents of DDRAM can
be read as well as written. This feature makes it possible both to display characters
and to query the device to see which characters are currently being displayed.
F
Freescale Semiconductor, Inc.
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