27 GRAPHICS ENGINE (GE)
27-24
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
DRAW_ERR[3:0]
Error
0b0010
Clipping area over The object/image drawn by a command with clipping area enabled is lo-
cated outside the clipping area. If a part of an object/image is beyond the
clipping area, the drawing within the clipping area is performed without
an error. Note, however, that error will results if a copy command, a block
transfer command, or the writing effect of rewrite follows a drawing opera-
tion by another command or a Fill/Mesh/XOR writing effect.
0b0001
Work area over
The object/image drawn by a command with clipping area disabled is
located outside the work area. If a part of an object/image is beyond the
work area, the drawing within the work area is performed without an error.
Note, however, that error will results if a copy command, a block transfer
command, or the writing effect of rewrite follows a drawing operation by
another command or a Fill/Mesh/XOR writing effect.
*
No drawing error occurs when another calculation error has occurred.
The command execution continues even if a drawing error and its interrupt occur regardless of whether drawing
error interrupts are enabled or not.
GE Reset
27.4.6
In order to initialize and relinquish the bus used, the GE can be reset via software. The GE supports two reset meth-
ods, hot reset and cold reset.
Hot reset
Hot reset initializes the GE with the command and work area address information maintained. The bus is relin-
quished. Perform hot reset if a command execution is terminated due to an unexpected operation.
To perform hot reset, write 1 to GE_HRST/GE_CTL register. GE_HRST retains 1 while the GE is placed into
reset state and it returns to 0 upon completion of the initialization. An execution start request using GE_RUN/
GE_CTL register is accepted even if the GE is in reset state and the command execution starts after the initial-
ization has completed.
The following information must be reset after a hot reset.
• Font (font configuration command)
• Clipping area (GE_CLIP_ST and GE_CLIP_END registers)
Cold reset
Cold reset initializes the GE completely.
To perform cold reset, write 1 to GE_CRST/GE_CTL register.
The reset state must be canceled by writing 0 to GE_CRST. If the initialization has not finished yet at this time,
DRAW_STS retains 1 and it returns to 0 upon completion of the initialization. An execution start request us-
ing GE_RUN/GE_CTL register is accepted even if the GE is in initialization state and the command execution
starts after the initialization has completed. After a cold reset, all the information must be reset.
Follow the procedure shown below to perform a cold reset.
START
END
GE_HRST
←
1
GE_CRST
←
1
DRAW_STS = 0?
no
yes
yes
BUS_STS = 0?
no
4.6.1 Cold Reset Flow
Figure 27.