32x64 LED monitor

Forum for discussion of electronic television. Generally, stuff to do with CRTs and not using mechanical displays.

Re: 32x64 LED monitor

Postby nanowaver » Sun Sep 09, 2018 6:31 pm

Have just seen these which look to be ideal for a 48 x 32 display.

https://www.ebay.co.uk/itm/P3-RGB-pixel ... SwrohZ4D1A

How easy are they to drive?

Baz
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Re: 32x64 LED monitor

Postby Steve Anderson » Mon Sep 10, 2018 12:03 pm

It's often the headache with e-bay and the like, "How about some data guys?" They say it's 'generic', but generic to what?

I've Googled the part number and the vendor and got nowhere - I might be interested in these too.

About the only useful info I've found is it requires 5V at 4A (20W) and the data and control are parallel not serial. The two sockets are for 'daisy-chaining' more than one display.

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Re: 32x64 LED monitor

Postby dominicbeesley » Mon Sep 10, 2018 8:49 pm

Hello, I'd start with this https://cdn-learn.adafruit.com/download ... matrix.pdf all the ones I got used something along these lines. I keep meaning to dig them out and get it all working again. I've been moving houses repeatedly this past couple of years and the LED matrix stuff is all packed up patiently waiting for me to get a workshop space sorted again, and the time!

Good luck an post to this thread if you have any questions, I'll try and rack my brains to remember how it all worked, if you'd like I can dig out my code - it was very specific to an arduino teensy using the ARM/SAM chip IIRC

D
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Re: 32x64 LED monitor

Postby dominicbeesley » Mon Sep 10, 2018 8:51 pm

PS: I didn't use the RGB matrix shield but if I was to do it again I probably would, either that, or use some sort of FPGA or CPLD to do all the bit shifting...
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Re: 32x64 LED monitor

Postby Steve Anderson » Tue Sep 11, 2018 1:49 pm

Thanks for the link Dominic - as mentioned there appears to be no datasheets or timing info 'out there', but it is a start. But I'm not going to rush into this as I have too much on my plate already!

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Re: 32x64 LED monitor

Postby dominicbeesley » Tue Sep 11, 2018 8:50 pm

No, there's not much out there at all. I had a lot of trial and error to get things working. First getting anything to appear took me a while then there was a lot of messing to get decent gamma. There are delays in turning the LED's on (but seemingly not off) which mean that the faster you drive the array - you need to do this fast! - the dimmer things become so PWM needs some thought.

Also, to get the teensy arduino running fast enough I had to do some funky things like splitting the PWM data into "planes" that roughly corresponded to powers of two of brightness and then using timers/interrupts to output each row for a set time....it's starting to come back - it was tricky but it worked. The display was pretty good I mainly was then trying to do fancy DSP to decode colour and sync everything up in the not very long time left over after all the bit shifting.

I really ought to get it finished and bring in to a convention! Where does all the time go?

D
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Re: 32x64 LED monitor

Postby nanowaver » Wed Sep 12, 2018 5:00 am

I'd be very interested to look at the code as I will need all the help I can get!

Baz
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Re: 32x64 LED monitor

Postby dominicbeesley » Thu Sep 13, 2018 11:39 pm

Hi Baz,

Zip file attached, the main .ino is full of some very scary looking stuff that is to do with reading the ADC port using DMA to buffers and then trying to tweak the timers so that everything lines up with the syncs and lots of DSP stuff to do colour decoding.

The main stuff for driving the RBG matrix, which is where you probably want to start is in DomRGBScreen.cpp and .h

I'm afraid its all a bit of a dog's dinner. Give me a shout if its not clear

D
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teensy_20160227.zip
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Re: 32x64 LED monitor

Postby Steve Anderson » Fri Sep 14, 2018 2:01 pm

"A dog's dinner." That brought a smile to my face - I haven't heard that expression in decades!

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Re: 32x64 LED monitor

Postby nanowaver » Fri Sep 14, 2018 11:12 pm

Dom
Many thanks! I must get down to my homework after a hearty dog's dinner!

Baz
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Re: 32x64 LED monitor

Postby nanowaver » Sat Sep 15, 2018 1:52 am

Dom

your code looks very impressive and much more sophisticated than my efforts so far - how do I send an attachment? I've tried both .ino and .txt files but they do not seem to be allowed.

Baz
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Re: 32x64 LED monitor

Postby smeezekitty » Sat Sep 15, 2018 2:39 am

nanowaver wrote:Dom

your code looks very impressive and much more sophisticated than my efforts so far - how do I send an attachment? I've tried both .ino and .txt files but they do not seem to be allowed.

Baz


.zip files are allowed
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Re: 32x64 LED monitor

Postby nanowaver » Sat Sep 15, 2018 3:25 am

Dom

see attached my feeble first effort!

Baz
Attachments
NBTV_monitor_GW3JGA_analog_in_software_08_ILI9341TFT.zip
(2.2 KiB) Downloaded 21 times
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Re: 32x64 LED monitor

Postby Steve Anderson » Sat Sep 15, 2018 2:05 pm

Zip files are allowed, there is a list of allowed attachment extensions that are valid. I'll see if I can post it here.

As you compose your message scroll down a little and you'll see a tab "Upload attachments" - from there it's pretty straight forward. Maximum file size is 20 Mb, you can attach more than one at a time, I've done 50 in the past.

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Re: 32x64 LED monitor

Postby nanowaver » Sat Sep 15, 2018 6:08 pm

Many thanks for the advice about attaching files.

Baz
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