27 GRAPHICS ENGINE (GE)
27-22
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
CALC_STS
CALC_STS indicates the GE calculator status. It is set to 1 when the GE starts initialization or when the GE
starts checking command parameters. It is reset to 0 after the GE has finished initialization or the parameter
check.
DRAW_STS
DRAW_STS indicates the VRAM writing status. It is set to 1 when the GE starts writing to the work area
(VRAM) and is reset to 0 after the writing has been finished.
Updated Range in Work Area
27.4.4
The area that has been rewritten by a drawing command can be checked using the GE_UPDT_ST and GE_UPDT_
END registers.
These registers retain the upper left and lower right coordinate values of the rectangular region that contains the ob-
jects/images that have been drawn.
X coordinate of upper left corner: UPDT_UPL_X[11:0]/GE_UPDT_ST register
Y coordinate of upper left corner: UPDT_UPL_Y[11:0]/GE_UPDT_ST register
X coordinate of lower right corner: UPDT_LWR_X[11:0]/GE_UPDT_END register
Y coordinate of lower right corner: UPDT_LWR_Y[11:0]/GE_UPDT_END register
Work area
(Clipping area)
UPDT_LWR_X[11:0]
UPDT_UPL_Y[11:0]
(0, 0)
UPDT_LWR_Y[11:0]
UPDT_UPL_X[11:0]
4.4.1 Updated Area
Figure 27.
The GE_UPDT_ST and GE_UPDT_END registers will be cleared by writing any value.
Notes: • The coordinates of the updated area can be obtained in the following cases:
1. At least one opaque dot of the specified object is located in the drawing area.
2. As for a transparent object in the drawing area, a copy command or a block transfer com-
mand is executed, or the writing effect of rewrite or mesh specifies the transparent color.
• The coordinates specified for drawing are logical values without consideration of the rotation
angle set by VWIN_ROT[1:0]/GE_ROTATE register. The GE converts the logical coordinates
into physical values according to the rotation information before it writes to the VRAM. The
update area coordinates are physical values after being rotated, therefore the update area co-
ordinates may differ from those specified by the commands.
Errors
27.4.5
Errors that may occur during command execution are divided into calculation errors and drawing errors, and a re-
spective interrupt can be generated when an error has been detected.
Calculation errors
If the GE detects an error while it is checking command arguments, the GE sets the error number to CALC_
ERR[3:0]/GE_IF1 register. A calculation error interrupt can be generated at this point. Read CALC_ERR[3:0]
in the interrupt handler routine to identify the error that occurred. The CALC_ERR[3:0] bits that have been set
are cleared by writing 0x0 or 0xff in byte to address 0x302448.