7'' TFT LCD Module

[odell]

Hi
I working on a project using a 7'' TFT LCD Module. It can run a images using a rca or vga.
The lcd can play video now. What I need to know is how make a video signal come from a Microcontroller.

http://www.ebay.com/itm/7-TFT-LCD-Module-2AV-Driver-Board-Touch-Screen-VGA-Car-Display-/320750841302?pt=BI_Electrical_Equipment_Tools&hash=item4aae3d6dd6#ht_6316wt_1270

[Psi]

It all depends on what you want to display.

If you just want to put some text and basic low resolution graphics on the LCD then you could use the RCA composite input.
Once you understand how a composite signal works it is possible to program a avr or pic to generate one.

Have a look at some of the composite on-screen display projects out there.
I've seen some that use an atmega and overlay text on top of a composite signal from a camera.
They're used to display flight stats on RC planes when doing POV flying.

On the other hand, if you want to display graphics and draw things you will be better off using some sort of VGA driver board with UART graphics library.
Using that you can talk to the driver board over serial and give commands to draw lines etc.


If you haven't bought that LCD yet then i recommend you pick one designed for what you want.
There are some LCDs that come with a vga controller and ARM micro built in.
They would be easier to drive as they come with pretty much all you need, including the micro.
Someone on this forum posted a ebay listing for one of them a month or two ago. Sorry, i cant remember the url.

[odell]

all it is going the display is a background image and text on top it and some small image

[Psi]

I've never programmed a micro to generate a composite signal myself so i'm not sure how complex you can make the image before you hit the limits of 8bit micros. I imagine the number of colors that can be generated is quite low due to the processing required.

If i was generating a composite signal i'd probably use a 32bit STM ARM micro so i have lots of speed available.



Here's someone making a composite signal with an atmega. Looks like they have implemented a graphics library as well
http://instruct1.cit.cornell.edu/courses/ee476/video/


Here's someone generating a VGA signal with an atmega
But, as you can see the pixels are quite large. That's because the 20mhz atmega cant generate the 25mhz pixel clock needed.
Because its clocking the data slower the resolution is less than 640x480. In this case its only 128x120 pixels
http://www-user.tu-chemnitz.de/~heha/Mikrocontroller/VgaGen/VgaGen.en.html

You will notice the code is in ASM. This is because the atmega is being pushed to the limit of what is possible on a 20mhz micro and the timing is critical.


A proper VGA driver board with graphics library will be 100 times better than both the methods above.
It will support the full resolution and allow you to draw any color. I think some allow you to load in bitmaps too.
And because you are just sending serial commands to the driver board speed isn't much of an issue.
The driver board takes care of updating all the pixels 60 times a second, you just tell it to draw a bitmap, or draw a box  etc. and it will be double buffered as well.

[Chet T16]

Any links for these vga driver boards? I've a project in the back of my mind that needs a 578i VGA signal

[kripton2035]

this board is a generic vga output board. I doubt you can send a video to it ...
http://shop.4dsystems.com.au/38-vga-embedded-vga-graphics-modules

with this chip from maxim, you can overlay text and graphics over a video :
http://www.maxim-ic.com/products/video/osd.cfm

hope this helps.

[odell]

what would be harder geting the 7'' TFT LCD Module working or putting a wifi module on the bored. and  makeing a app for a smart phone. so you can use the phone lcd.

[Short Circuit]

Depends on the parts involved and your definition of working. Getting something to work from hardware perspective (after which it becomes someone elses problem) is quite different from getting it to work from project perspective...

Anyway, you might want to check into these displays, programmable, available from 3.5 to 7 inch, and quite affordable;
http://www.itrontft.com/tft/ with this (or similar product), a TFT solution is the easy way.

[odell]

I'm looking it a new lcd. it is a 7.0" itron SMART TFT Module. What I like to know is how many i/o pins dose it have and is the cpu on the lcd is powerful enough the run a  fan controller circuit  or do i need to put a Microcontroller on it to run the fan controller. The fan controller has 20 temperature sensors and 14 Transistor 1 for each fans so there is 14 120mm fans. I'm thinking of using multiplexing.

[joelby]

Have you read the itron module's data sheet?