Q&A Technology and Design
- What is the write timing?
- Do I have to always connect with WAIT?
- I want to speed up the drawing write speed; how fast can it go?
- How do I use the two-layer superimposing display mode?
- Tell me about the automatic blinking.
- Are there important points to keep in mind for the pattern design?
- What type of CPUs do you recommend using?
- Is the sample source also included in the starter kit without a C compiler?
- Which compiler is the sample source included in the starter kit for?
What is the write timing?
We receive this question most often.
For anyone who has experience with the use of GDC etc., we believe he/she would have experienced trouble with this point.
Our LCD controller does not require any consideration of write timing, and so write is always possible.
It’s like writing to the local SRAM.
Do I have to always connect with WAIT?
It is not necessary, but when not connected, the bus timing must be operated at a considerably slower speed; this is disadvantageous for drawing speed.
I want to speed up the drawing write speed; how fast can it go?
All of our LCD controllers are set at about 250nS (please refer to the specific manual).
If the Host-CPU is fast enough, even if only one dot at a time is drawn, one screen finishes in 19.2mS in the case of QVGA.
Therefore, 30 fps video is also feasible.
However, in this case, the Host-CPU cannot keep up with this speed.
By using a Host-CPU that is fast enough, speed that is proportional to it can be displayed.
Additionally, for customers who want to draw at high-speed by using slower, low-cost CPUs, w
e already provide a hardware drawing engine called a “mini-accelerator.”
How do I use the two-layer superimposing display mode?
Image a drawing method in which a bar graph is expanded and contracted on plotting paper.
When the bar graph is expanded, there is no problem, but when contracted, it is necessary to redraw as the background graphing paper also disappears.
However, when using the two-layer superimposing function, it is not necessary to redraw the display as the layers can be separated.
Tell me about the automatic blinking.
In 64-color mode, automatic blinking of pixels can be performed using the complementary color. The complementary color of 0011.1111 (white) is 0000.0000 (black). The complementary color of 0011.1100 (yellow) is 0000.0011 (blue).
Are there important points to keep in mind for the pattern design?
As the speed is fast between the high speed SRAM and the LCD controller, make the pattern length as short as possible. Moreover, as VGA and higher resolutions are faster, isometric wiring of the bus is ideal. For details, please refer to the specific manual.
What type of CPUs do you recommend using?
For the bus timing, the requirement is that the RD and WR are asserted after waiting for 5nS or more after the CS and address are fixed. Almost all of the general Motorola CPUs conform to this. Please check to make sure. Also, please be aware that KL (Kawasaki Steel) (Z80 compatible) and some STMicroelectronics CPUs do not conform. Meanwhile, almost all of the Renesas CPUs are OK.
Is the sample source also included in the starter kit without a C compiler?
Yes, the sample source is included and is free of charge.
Which compiler is the sample source included in the starter kit for?
At one time, we offered source code for the EWSH (IAR) compiler; however, now we focus on and provide libraries for HEW (Renesas) and YCSH (Yellowsoft).
