
102
EPSON
S1C88409 TECHNICAL MANUAL
CHAPTER 5: PERIPHERAL CIRCUITS AND OPERATION (LCD Controller)
GS10–GS17: Gray-scale (0, 1) conversion code
setting register (00FF68H)
GS20–GS27: Gray-scale (1, 0) conversion code
setting register (00FF69H)
GS30–GS37: Gray-scale (1, 1) conversion code
setting register (00FF6AH)
Sets the gray-scale conversion code.
When "1" is written: Dot goes ON
When "0" is written: Dot goes OFF
Reading: Valid
The GS1, GS2 and GS3 registers correspond to
gray levels 01B, 10B and 11B, respectively.
Each register specifies a display pattern for eight
frame cycles, thus the intensity of each gray level
can be set. D0 to D7 in the register control dots on
(1) and off (0) in each frame cycle.
At initial reset, the GS register is set to "00H"
(OFF).
PLCD0, PLCD1: LCD controller interrupt
priority register (00FF21HD0, D1)
Sets the priority level of the LCD controller
interrupt.
Table 5.10.11.3 shows the interrupt priority level
which can be set by the PLCD register.
Table 5.10.11.3 Interrupt priority level settings
PLCD1
1
0
Interrupt priority level
Level 3
Level 2
Level 1
Level 0
PLCD0
1
0
1
0
(IRQ3)
(IRQ2)
(IRQ1)
(None)
At initial reset, the PLCD register is set to "0" (level
0).
ELCD: LCD controller interrupt enable register
(00FF25HD2)
Enables or disables the LCD controller interrupt
generation to the CPU.
When "1" is written: Interrupt is enabled
When "0" is written: Interrupt is disabled
Reading: Valid
The ELCD register is the interrupt enable register
corresponding to the LCD controller interrupt
factor. When this register is set to "1", the interrupt
is enabled, and when it is set to "0", the interrupt is
disabled.
At initial reset, the ELCD register is set to "0"
(interrupt is disabled).
FLCD: LCD controller interrupt factor flag
(00FF29HD2)
Indicates the generation of LCD controller inter-
rupt factor.
When "1" is read: Int. factor has generated
When "0" is read: Int. factor has not generated
When "1" is written: Factor flag is reset
When "0" is written: Invalid
FLCD is the interrupt factor flag corresponding to
the LCD controller interrupt. It is set to "1" when a
software one-shot data transfer or a hardware auto
transfer has completed.
At this point, if the corresponding interrupt enable
register is set to "1" and the corresponding inter-
rupt priority register is set to a higher level than
the setting of the interrupt flags (I0 and I1), an
interrupt is generated to the CPU.
Regardless of the interrupt enable register and
interrupt priority register settings, the interrupt
factor flag is set to "1" when the interrupt genera-
tion condition is met.
To accept the subsequent interrupt after an
interrupt generation, it is necessary to reset the
interrupt flag (set the interrupt flag to a lower level
than the level indicated by the interrupt priority
registers, or execute the RETE instruction) and to
reset the interrupt factor flag. The interrupt factor
flag is reset to "0" by writing "1".
At initial reset, the FLCD flag is reset to "0".