Help building 256 shades Monochrome LED Display

[Windom]

multiplex 8x8 rgb building

Hello YUV,

I have a PM for U. Can you please reply. Tnx
Windom

 

[Bus Master]

pwm software methods of driving rgb led matrix

Rocketmagnet,

I think you will need to use an RTOS for this program scheme. Or u have another approach for controller time sharing?

 

[lzgq771001]

64x64 led matrix animation circuit

you can look here
www.ledall.com

 

[VSMVDD]

a line pwm scanning for led sign board

i am about to restart work with vidx.dll within proteus vsm

i find this topic interesting

as i have built the dll like this
using pixels instead within c++ code

it runs at 50fps refresh and has 65535 shades of greyscale
so is 16bit

so far i have a white level and black level ok
so ill start to add further code to the arrays to encode and decode the scallers
by using a voltage sample in spice

if someone wants to do the internet work and or contribute to this project

i am happy to work with others


i have half built today the generator for white levels only so far..

let me know @ vsmlibs@yahoo.co.uk or vsmvdd@yahoo.co.uk

 

[Bus Master]

human eye sensitivity led pwm

Hi all,

Where can i buy an RGB LED Cluster like the one used in Xilinx Times square LED screen?
(**broken link removed**)

Or any LED cluster that i can use in my outdoor RGB LED screen?

Please advise.

Yours,

 

[techie]

avr led gamma correction

Busmaster, there are hundreds of companines making these. You can search at www.globalsource.com for these.

 

[YUV]

vidx.dll proteus

Hi all,
Where can i buy an RGB LED Cluster that i can use in my outdoor RGB LED screen?

**broken link removed**
**broken link removed**

 

[asuncao]

dot matrix 16x16 tlc5921

hi..

i have been workin on my rgb led project, i was just thinking of using specific ics for pwm generation. because i dont know cpld,fpga.. i am planning to use max7313 or max6966. they have 16 pwm outputs and each output has 8bit pwm intensity setting .. 64 number of 7313's can be addressed on the same i2c bus. and 6966 uses spi communication. but for the speed , it more beneficial to use 7313.....

should i learn cpld besides i really dont know anything about it, or should i continue?
i konw there is a lot to do on this, but i am on the very beginning..

and i am planning to the scanning process using 16f877. do i need to use an atmel or something different. (i havent used a chip other than pic before.)
helps would be greateful .. thanks

 

[asuncao]

sample matrix rgb proteus

any answer??

cuz i am really in trouble..

 

[Bus Master]

mbi5026 led matrix

asuncao,

I think you have to use an FPGA based microcontroller because of the very high refresh rate needed in the display unit. So many calculations are needes, specially if you will implement a color Gama correction routines. These calculations needs a realtime multipliers (Implemented using Look-Up Tables -LUT-) and will be very slow if a conventional microcontroller is used.

Hopr this helps.

 

[asuncao]

mbi5026 mosfet

for now;

i just want to implement a picture on my led panel. i know fpga is need for big applications but cant i do it with microcontroller and driver ic s ??

how many pwm outputs can fpga or cpld can give me? as many as i want? and think of learning time, how long will it take?

 

[YUV]

64x64 pixels led pic circuits

for now;
i just want to implement a picture on my led panel. i know fpga is need for big applications but cant i do it with microcontroller and driver ic s ??

Rather, no. Microcontroller can serve signboards with text features. Displaying of a graphic information requires more powerful device. Of course, some processors have a very high operation frequency. But I wouldn't stick the prefix "micro" to them.

[/quote]how many pwm outputs can fpga or cpld can give me?[/quote]
The range of CPLD or FPGA is very wide. You can choose any manufacturer and any family of devices. You just have to understand requirements of your project.

[/quote] as many as i want?[/quote] You know... We don't have telepathic capabilities...

[/quote] and think of learning time, how long will it take?[/quote] Fully depends on you. Nobody can tell you.

And now, a small example about driving of LED panel.
Assume, you have 8x8 RGB matrix and want to show full-color static picture.
Assume, your panel has 1/8 duty and you have to scan it line-by-line.
Let's calculate timings. 1 sec / 100 frames per second / 8 lines / 256 grades.
So, you have 4.88 microsec to shift RGB data for whole line into LED driver ICs. Of course, data must be decoded to serial. Calculate clock frequency yourself.
With this calculation you will get 256 linear grades for each color. If you want to make a gamma-correction, you should make a quantity of linear pieces as many as possible.
FPGAs usually have memory blocks inside, you can easy store your picture there.

Regards, YUV

 

[asuncao]

mbi5026 spice

now, i decided to learn the cpld and fpga. i also want to build my own full color led panel. typical fpga has 80 outputs that is not enough for a wide panel. will i use again the led driver i/o expanders? or is there another solution for that?

and the main subject is where to start for fpga. any tutorials ?? help?

 

[techie]

led screen refresh rate calculate pwm

you need serial to paralled LED drivers like TB62705. With that you require very few pins on FPGA.

 

[YUV]

led screen schematic

now, i decided to learn the cpld and fpga. and the main subject is where to start for fpga. any tutorials ?? help?

Altera has a free software, so-called "web-version". It doesn't support all devices, but it is quite enough for a beginning.

you need serial to paralled LED drivers like TB62705. With that you require very few pins on FPGA.

Exactly!
I think, FPGA will not be able to drive all outputs simultaneously @ high current.
LED driver IC can supply up to 90mA to each output.
But I would rather use MBI5026 (Fclk = 25MHz), because TB62705 is too slow.

 

[RichardH]

led screen @yahoo.com

I have a couple of questions

if you wanted to display video on something like this, would you use a frame store then display the image from there or could you simply sample the video (at a preset rate depending upon the number of pixels your display has) and clock it out to the LED drivers??

Am I better to multiplex using say the Macrobloc drivers for the CC and transistors for CA or drive each LED using a Macrobloc driver? I am sure it will be brighter and more even if the outputs are driven directly, but I am not sure of the pros and cons of each method.

Finally, if I PWM (on say the OE of the LED drivers) to get brightness control of the whole board, how do I achieve the greyscale on an individual pixel?

 

[YUV]

led matrix driver 8x8 1/8 scale

I have a couple of questions
if you wanted to display video on something like this, would you use a frame store then display the image from there or could you simply sample the video (at a preset rate depending upon the number of pixels your display has) and clock it out to the LED drivers??

You must use several frame buffers to avoid moving artefacts.
Output clock may differ from the input one.

Am I better to multiplex using say the Macrobloc drivers for the CC and transistors for CA or drive each LED using a Macrobloc driver? I am sure it will be brighter and more even if the outputs are driven directly, but I am not sure of the pros and cons of each method.

1st method - you will get problems with compensation of scan on adjacent panels.
2nd method - so called "static control". It has much higher brightness, but requires more drivers.

Finally, if I PWM (on say the OE of the LED drivers) to get brightness control of the whole board, how do I achieve the greyscale on an individual pixel?

No. You can't separate a single output with OE, it takes effect onto whole chip,

 

[drbizzarow]

tlc5921 led matris

i think we have to restart this topic again

 

[drbizzarow]

led driver rgb cluster building

any comments freiends ......pls

 

[NAresh123]

fpga led display

I need help for rgb display