<14/54>VDP1 User's Manual/4.3 Plot Trigger Register

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VDP1 User's Manual/Chapter 4 System Registers

■4.3 Plot trigger register

The plot trigger register (PTMR, Plot trigger mode register) controls the start of drawing. This is a 16-bit write-only register located at address 100004H. After power up or reset, the value is reset to 00B. Fix unused bits to 0.

PTMR 100004H (R) bit15 bit14 bit13 bit12 bit11 bit10 bit9 bit8 bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PTM

Plot trigger mode: plot trigger mode(PT), bit0,1

Controls the start of drawing. When the plot trigger mode is 10B, drawing starts automatically at the same time as the frame starts. If the plot trigger mode is set to 01B, drawing will start as soon as it is written to the register. If you write 01B to the plot trigger mode while drawing, drawing will start from the beginning of the command table at that point. When the plot trigger mode is 00B, drawing will not start even if the frame starts. It will be idling. After power up or reset, the value is reset to 00B.

PTMR 100004H (R)	bit15	bit14	bit13	bit12	bit11	bit10	bit9	bit8	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
0	0	0	0	0	0	0	0	0	0	0	0	0	0	PTM

PTM		drawing mode
bit 1	0	drawing mode
0	0	Idle with frame switching
0	1	Start drawing when 01B is written
1	0	Automatically starts drawing when switching frames
1	1	Setting prohibited (please do not set)

When the plot trigger mode is rewritten from 01B to 00B or 10B, it becomes effective from the next frame buffer switching timing. However, when the plot trigger mode is changed from 00B or 10B to 01B, it becomes effective at that point, and drawing starts even after automatic drawing with 10B. If the table is not rewritten, the same drawing will be performed, so the results of translucent color operations will change. If you want to change only the drawing start mode without drawing, do the following. Change the plot trigger mode from 10B to 00B. In the next frame, change the plot trigger mode from 00B to 01B.

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