Led Matrix: Unterschied zwischen den Versionen

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~~For the LED Matrix we want to build on the [[CCCamp2007]] we decided to design our own LEDMatrix Controller/Driver setup. It will consist of two parts.~~

=== WTF? ===

~~== LED Matrix Driver Boards ==~~

[[Bild:Matrix_frontside.jpeg|thumb|200px|hypnomatrix is hypnotizing]]

~~Our Matrix should have a resolution of 48x72 pixels~~. ~~So there will be 48 rows and 72 columns. The basic building block of our ledmatrix will consist of an 8x8 pixel module (or 8x48 or 8x76 depending on~~ the ~~levels of grayscale steps you want).~~

[[Bild:Matrix_backside.jpeg|thumb|200px|all hail to the hypnomatrix]]

~~for our matrix~~ we ~~need 6x9 = 54 modules~~.

For the LED Matrix we wanted to build on the [[CCCamp2007]] we decided to design a GNU LEDMatrix Controller/Driver setup. It consists of two parts the FPGA board and a several driver electronics boards. Now almost one year later we're finally done!

So how is such basic building block connected? The cathode (GND) pins of all LEDs in each of the 8 rows are connected to each other. Also all the annode (+) pins of all lesds in each column are connected. Sowe get 8 rows and 8 columns. ~~each column intersects each row and the intersections are the leds~~. ~~To lighten up one specific led we have to set the row the~~ led ~~is connected to to GND and the column to +5V~~ (~~we also need a resistor to limit the current~~)~~. TODO: das besser erklaeren rasteransteuerung etc.~~

''see also:'' [http://www.flickr.com/photos/1000points/2509802438/ metalab led matrix - demo "die ewigkeit schmerzt"](Video)

~~The 8 rows are each connected~~ to a ~~powermosfet and are driven~~ to ~~ground~~ one at ~~a time~~ (so the ~~matrix is 8times multiplexed)~~.

== Animations ==

~~For driving~~ the ~~mosfets we~~ use ~~2x Quad-mosfetdriver which~~ in ~~turn are controlled by a 8bit shifting register~~.

Two Animations for the linuxwochen: [[Bild:Metalabanim.zip]]

<div>

<div style='float:left'>{{#ev:youtube|pHdAvMrkO0U}}</div>

</div>

== Status ==

Everything is soldered and it works. We can stream videos via the parallel interface of the via board to the matrix with 72fps :)

* main svn: https://whatever.metalab.at/projects/FPGAMatrix/

* cliffords mplayer patch: http://svn.clifford.at/handicraft/2008/metaleds/

== Usage examples ==

clifford/mplayer/mplayer-bin -vo metaleds:/dev/lp0 -framedrop -vf scale -zoom -x 72 -y 48 test.avi

netcat -l -p 7000 > /dev/lp0

Format is: 72x48 bytes of pixeldata (ranging from 0x00 to 0x0F) followed by a single 0x80 (to flip framebuffers)

== Real-time access ==

=== Raw protocol ===

72x48 = 3456 octets of pixel data followed by a terminating 0x80 octet.

Each pixel data octet represents one pixel's brightness, ranging from 0 (0x00, off) to 15 (0x0F, brightest).

The pixels start at the upper left corner and are numbered in [http://en.wikipedia.org/wiki/Row-major_order row-major order] (see the diagram below).

All output is double-buffered on the fpga, so you have to send a 0x80 after the pixel data to flip the frame buffers.

<pre>

________________________

| 1 2 3 ... 72|

|73 50 ... 144|

|. |

|... 3456|

|________________________|

</pre>

=== Using with C/C++ ===

You can use the metalib library from here; it comes with a couple of demos:

https://whatever.metalab.at/projects/FPGAMatrix/client/

=== Using with Python ===

You can use functions like getpixel, setpixel, submit with the python classes in https://whatever.metalab.at/projects/FPGAMatrix/python/

It supports the (now encouraged) way of using TCP. A example (Game of Life) is available.

~~For the columns we take almost the same components except that we don|t need the mosfets. the mosfet drivers~~ (~~which consists of mosfets of course - in fact its a half bridge and so contains one pMOS and one nMOS FET~~) ~~are strong enough to drive a high current led with a constant current of 0~~.~~5A and peak currents of~~ 1~~.5A~~

== Specs ==

72x48 pixels totals 3456 blue leds

54 column driver modules (current source).

1 row driver mudule (current sink)

~~=== partlist ===~~

The 8 rows are each connected to a powermosfet and are driven to ground one at a time (so the matrix is 8times multiplexed).

~~link~~ to ~~spreadsheet: http://spreadsheets.google~~.~~com/ccc?key=pZBTqi6Tn2l3eL8mkHINYJQ&hl=en~~

For driving the mosfets we use two Quad-mosfetdriver which in turn are controlled by a 8bit shifting register.

~~<websiteFrame>~~

~~website=http://spreadsheets.google~~.~~com/ccc?key=pZBTqi6Tn2l3eL8mkHINYJQ&hl=en~~

~~height=300~~

~~width=640~~

~~</websiteFrame>~~

For the columns we take almost the same components except that we have to source current. The mosfets can source up to 250mA but we limit it to about 20mA.

=== Used ICs ===

* [http://www.onsemi.com/PowerSolutions/product.do?id=NID5001N NID5001N] MOSFETS for the row driver

* [http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en010678 TC4467] used as column driver

* 74HC595 shifting registers

== New MiniITX Board ==

VIA EPIA-M 1000G

1 Ghz

1 Gig RAM

MPEG2 Decoderchipset

~~==== chips that might be usefull for a LED matrix in general ====~~

* Texas Instruments

** [http://focus.ti.com/docs/prod/folders/print/tpic6595.html TPIC6595] 8-Bit Power shifting register (250mA continious current per channel)

** [http://focus.ti.com/paramsearch/docs/parametricsearch.tsp?family=analog&familyId=356&uiTemplateId=NODE_STRY_PGE_T TPIC6C595, TPIC6B595, TPIC6A596] all simmilar to the above, ALL switch to ground

** [http://focus.ti.com/docs/prod/folders/print/tps1120.html TPS1120] Dual P-channel Enhancemenent-Mode MOSFET

* On Semi

** [http://www.onsemi.com/PowerSolutions/parametrics.do?id=809 MOSFETs] I think we|ll use one of thes for the rows

** [http://www.onsemi.com/PowerSolutions/parametrics.do?id=557 Shifting Registers] cheap :)

~~== FPGA LED Matrix Controller ==~~

[[Kategorie:WhateverLab]]

~~an FPGA producing the correct signals to drive the above driver module, or drive many modules in paralell~~ :~~) for each module we need 3pins~~

[[Kategorie:Projekte]]