Vb_driver - a variable brightness upgrade for older grids

[stevieraysean]

Programming and test jig PCB arrived!
Programming and test jig parts arrived!
Through hole (40h kit) adapter revision pcb arrived!

Just gotta find some time to build them. This week hopefully.

Also quotes on vb driver PCB fabrication and assembly are done. Just need to confirm everything works between the latest vb revision and the programming and test jig before going ahead with the first small run.

[noiserock]

What sort of programmer does one need? I have a PicKit and is willing to do some testing(and soldering) of my walnut 64.

[frankchannel]

Does anyone (@tehn?) know what LED driver(s) the most recent grid edition uses?

The as1130 chip is neat. @stevieraysean: I’m curious how your system works. I assume the microcontroller on your driver board takes the serial input sent to the old MAX driver and converts that to an i2c message for the new as1130 driver? The other thing it must do is convert the LED matrix into a charlieplexed matrix, though I don’t really understand how you’re able to do that…

[tehn]

TLC5940. two of them configured to multiplex four rows with mosfets. pretty straight foward setup similar to the datasheet. (you’ll find that most electronic solutions are minor variations of example usage in datasheets)

[stevieraysean]

What sort of programmer does one need? I have a PicKit and is willing to do some testing(and soldering) of my walnut 64.

You need to be able to program an AVR ATMEGA325. from searching the internet it seems the pickit can do some AVR chips. I cannot help with this as I don’t have a pickit. as long as it can write the hex files and burn the fuses correctly. there are many way to program microcontrollers.

The pololu AVR programmer i recommended is $7.77

I assume the microcontroller on your driver board takes the serial input sent to the old MAX driver and converts that to an i2c message for the new as1130 driver?

correct

The other thing it must do is convert the LED matrix into a charlieplexed matrix, though I don’t really understand how you’re able to do that

no, it rectifies, or de-charlieplexes the outputs of the AS1130 so that it’s output is identical to the MAX7219, albeit with better features.

I looked at probably every LED driver under the sun to find this solution.

The problem was the way the grid is connected to the MAX7219 is basically backwards to how every other LED driver I could find works. common cathode vs common annode, which made it very difficult to find a solution, particularly one that would be small enough to fit a PCB of the same profile.

[frankchannel]

no, it rectifies, or de-charlieplexes the outputs of the AS1130 so that it’s output is identical to the MAX7219, albeit with better features

Thanks for the info. After some additional googling I found this site which helped me understand how to drive a standard LED matrix with a charlieplexed style driver.

[stevieraysean]

nice link!

I’ll write about this more eventually, but i used two output pins from the AS1130 into two schottky diodes to drive the LED annode. this means that when an output is acting as ground there was another pin that could drive that annode. thus filling in the diagonal black squares (in your link) and letting me put the full 8x8 matrix on there.

[ado]

Nice work. I’m keen for a 40h kit.

[jemfiner]

Hello,

I’d like to put my name down for an upgrade for a 2011 128 walnut grid (m128-101) please !

[IcaroFerre]

Awesome work. I’d also be interested in a kit for a 40h!

[stevieraysean]

Hey everyone, just checking in.

Our new baby has been all consuming, as you would expect.

This is still happening.

I’ve made up the programming and test jig. Need to make up the final vb prototype to test everything. I expect it will all work fine.

Then I can get on with manufacturing.

Grateful for your patience.

[Oootini]

Take your time! New children are all consuming.

[kasselvania]

I’ve got our first coming in about 60 days. Just the preparation alone can be pretty consuming, so I can only assume what it’ll be like when the little guy arrives! Thanks for the update and of course, we are all grateful for all you’re giving the community in regards to this project!!

[sonoCircuit]

Holding my sleeping 1 week old child in my arm right now.
Time consuming but truly amazing. You have my full support.

[stevieraysean]

Hello everyone

I just wanted to give an update on this project before the end of the year.

I have built the programming and test jig, and also what I think will be the final prototype for vb_driver.

I have not tested these fully yet as I have not had the time. I’m already aware that I messed up a footprint on the jig for the display, so I’ll need to do some hacking to get that going properly.

I am aiming to get these two things tested/finalised early in the new year and start the process for producing these for sale around February.

Still some work to be done finalising firmwares for other editions.

Here’s a shot of the latest prototype

Hope you all are having a great holiday season.
Thanks again for your patience.

!

[kasselvania]

It lives!!! Been using an old Greyscale for some legacy scripts recently and was thinking how nice it would be to have the white LED’s be vari-bright. Looking forward to this!

Thanks for your continued hard work! Happy holidays!

[Justmat]

I am so happy to see this update! Happy holidays!

[Oootini]

Yup very excited to get this installed. I’m currently repairing a gs64 with a broken usb connector, will be a great addition to add a vb_driver circuit. Also available for testing in whatever capacity I can help. I have an atmega avrisp mkii programmer at hand, etc

[VXQN]

Very pleased to see further progress on this, absolutely fantastic work!

[woofy]

So exciting, my 128 walnut can’t wait to be lit in varieties