Fusion Brain + Colour LCD = Cool Beans

2k1Toaster · 06-16-2009, 06:39 AM

Just thought I'd share what I have been working on. It will be part of my senior design project for university, but if there is enough interest maybe we can consider selling a kit.

The LCD is a 132x132 and supports 12bit colour. Nothing fancy about the screen, it is a chinese knockoff of the Nokia 6610 screen on a generic breakout board so I could prototype fast.

The board between the LCD and the FB is just an inverter and some resistors. Basically the FB has switched grounds, and for simplicity in testing, I wanted switched 5v, so voila. Then there is some current limiting and stuff for the screen backlight.

Here are the pics, enjoy!

DEV8ED · 06-16-2009, 07:52 AM

looks tops i ll be interested in a kit although i can't think of anything to use it for yet LOL

Iamthehor · 06-17-2009, 12:03 PM

Excuse the electronics ignorance: Is this using PWM? or how else do you tell the screen what to display?

2k1Toaster · 06-17-2009, 12:39 PM

Quote: Originally Posted by Iamthehor

Excuse the electronics ignorance: Is this using PWM? or how else do you tell the screen what to display?

Serial communication. The main points are there is a clock, data, and select line (there are more but these are the most important). So minimum of 3 digital outputs are used (I use 4 data + 1 main power control though).

When you want to talk to the screen you have to enable the select line. This tells the screen to actually pay attention to the other lines.

Then you set the data out to either on for a logic 1 or off for a logic 0. Then you pulse the clock line. Voila 1 bit of data is sent.

Now to get anything useful you have to do this a lot. And I mean ALOT. To tell the screen "Hey I am going to send some data about a pixel", you have to send 18bits of data. Then you have to tell it the location where this data will be for (the pixel's coordinates) which is another 18bits. Then you send it the pixel data which is 12bit colour, but since I use 9bit serial protocol, it is another 18bits.

So to tell 1 pixel to turn 1 colour, it takes 54bits of data, each of which requires the clock to pulse 2 times (one for high, one for low), so it takes a grand total of 108 various states of the digital outputs for that one change.

Multiply 132x132= 17424 pixels each that take 108 states and you can see how video is so complicated.

There is also a huge function with specialized commands and data that needs to be sent to the LCD as soon as it is powered on or else it does nada.

There is more to it than that, but that is the simple explanation.

monty9991 · 06-17-2009, 12:53 PM

how about have an analog clock on this screen.

2k1Toaster · 06-17-2009, 01:34 PM

Quote: Originally Posted by monty9991

how about have an analog clock on this screen.

Yes it is possible. Anything can be drawn there with enough programming.

hommersimpson · 06-17-2009, 02:09 PM

How about 2 hooked to cameras and used as side view mirrors ?

zillacles · 06-17-2009, 04:59 PM

Nice, I've been looking into adding an LCD into my system but haven't had any luck finding any good low-profile screens, either colour or black and white. By low profile I mean minimal circuit board overhang around the screen so save on space. Have you got any suggestions?

Maheriano · 06-17-2009, 05:11 PM

What exactly is this for? I can see it's a screen but what are the advantages of this over any other screen?

colin · 06-17-2009, 05:25 PM

Its controlled by the Fusion Brain as opposed to a VGA output. Its for drawing stuff on a small screen without using the computer.

kloves2fly · 06-17-2009, 09:49 PM

can it control bigger screens? with the right code can it refresh a screen like in ms or less?
my thoughts are to replace the instrument cluster - odometer, tach, gas etc - with an LCD screen that will display all these info n anything the FB controls

colin · 06-17-2009, 11:18 PM

You would probably want a customized board for that. USB is usually on a polling interface where it refreshes every 10 ms with the computer. If you're not using USB features and you need a screen to refresh in a ms, you would need a lot of operations done in one second and therefore a lot of processing power. At 800x600, that's 480,000 pixels to control. Three colors each = 12 bits = 2 cycles on a typical 8-bit data bus.
480,000 * 2 = 960,000 instructions. Plus all the initializations that 2k1toaster was talking about, youre talking a fast machine!
If it's at 108 states per pixel, like 2k1toaster was saying, that's over 5 million state changes. Every 10 ms...

See where im going with this? You would want a board with a stronger interface to the LCD, then you'd want some hefty processing power, and you'd want an interface board so that you can separate LCD code from the code that determines what picture ends up on the screen / reads the information from the sensors.

Iamthehor · 06-18-2009, 10:17 AM

Quote: Originally Posted by 2k1Toaster

Serial communication. The main points are there is a clock, data, and select line (there are more but these are the most important). So minimum of 3 digital outputs are used (I use 4 data + 1 main power control though).

When you want to talk to the screen you have to enable the select line. This tells the screen to actually pay attention to the other lines.

Then you set the data out to either on for a logic 1 or off for a logic 0. Then you pulse the clock line. Voila 1 bit of data is sent.

Now to get anything useful you have to do this a lot. And I mean ALOT. To tell the screen "Hey I am going to send some data about a pixel", you have to send 18bits of data. Then you have to tell it the location where this data will be for (the pixel's coordinates) which is another 18bits. Then you send it the pixel data which is 12bit colour, but since I use 9bit serial protocol, it is another 18bits.

So to tell 1 pixel to turn 1 colour, it takes 54bits of data, each of which requires the clock to pulse 2 times (one for high, one for low), so it takes a grand total of 108 various states of the digital outputs for that one change.

Multiply 132x132= 17424 pixels each that take 108 states and you can see how video is so complicated.

There is also a huge function with specialized commands and data that needs to be sent to the LCD as soon as it is powered on or else it does nada.

There is more to it than that, but that is the simple explanation.

Surprisingly, that's not that far from what I had thought. I had no idea how to take it from idea to expression though (and my concept was just a tiny bit simpler

) I didn't think PWM would be useful, but PWM make more sense in my mechanical brain.

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