27 GRAPHICS ENGINE (GE)
27-20
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
Controlling GE
27.4
The GE sequentially executes the commands written to the memory to draw objects/images. The drawing area,
mesh, and transparent color are set using the registers. To alter the registers while commands are being executed, a
command to write data to the registers is provided.
This section explains initializing the GE and executing commands. For detailed information on the commands and
registers, see Sections 27.5 and 27.6, respectively.
Initial Settings
27.4.1
The GE enters reset state after an initial reset. The operating clock is supplied from the CMU.
The following shows the procedure required to use the GE.
(1) Canceling GE reset state
Write 0 to GE_CRST/GE_CTL register to cancel GE cold reset status.
(2) Initializing the GE registers
Make the following settings using the GE registers.
1. Select a bpp mode and LCD sync condition. (GE_DISP_CFG register)
2. Select an angle of VRAM rotation. (GE_ROTATE register)
3. Set the work area. (GE_WK_ADDR and GE_WK_SIZE registers)
4. Set the clipping area. (GE_CLIP_ST and GE_CLIP_END registers)*
5. Select a mesh pattern. (GE_MESH register)*
6. Set the transparent color. (GE_MAGIC register)*
7. Set Palette 1 contents. (GE_PALETTE1 register)*
8. Sets CCT1 (color conversion table 1) contents. (GE_CCT1_4BIT, GE_CCT1_2BIT, and GE_CCT1_1BIT
registers)*
9. Set the command start address. (GE_CMD_ADDR register)
10. Enable GE interrupts. (GE_IE register)
* It is not necessary to set these registers if the functions are not used.
(3) Programming drawing commands
Write the commands to be executed to the memory (beginning with the command start address). IVRAM (Area 3)
or an external memory located in Areas 13 to 22 can be used for executing drawing commands. The commands
written to IRAM (Area 0) cannot be executed.
Write the command for drawing the backmost object/image first. Commands and arguments must be written
successively without a blank.
To alter the GE registers while commands are being executed, use the GE_CONFIG command.
Use a STOP command at the position to stop the command execution. The GE provides four STOP commands,
STOP1 to STOP4. The application can confirm which STOP command is used after a command list has been
executed (an interrupt has occurred) by reading the interrupt flag (EXE_END[2:0]/GE_IF3 register).
Note: Commands must begin from a word (32-bit) boundary address.
Command Execution and Termination
27.4.2
Starting execution
Writing 1 to GE_RUN/GE_CTL register starts command execution. The GE fetches the commands and argu-
ments in 32-bit units beginning from the address set in the GE_CMD_ADDR register, and executes them suc-
cessively. The GE_CMD_ADDR register contents are updated by fetching each command.
Terminating execution
Termination by a STOP command
The GE command stops executing a command list when it executes a STOP command (STOP1 to STOP4).