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SMD LED Matrix Booster


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****Kits available in the 43oh store

 

 

Sorry about the focus on the video - my camera didn't like the bright LEDs moving all over the place :smile:

 

This was created as a SMD learner board.  There are 90 SMD components (2 shift registers, 8 transistors, 64 LEDs and 16 resistors).  LEDs are arranged in a Common Cathode configuration.

 

I've attached the eagle files, two CCS projects (one that's the Game Of Life demo seen in the video, the other is a test) and a test Energia project (although I'm having trouble getting it to refresh the display fast enough).  

 

I'll post BOM in a bit.  I ran into a bit of an issue - the pinout for the transistors that I picked from eagle had two of the pins swapped, so I had to solder them upside-down.  Not too bad - I've already got a fixed design in eagle.

 

***Attachments***

LED_MatrixEnergia.txt - test file for Energia

LED_Matrix_V1_Eagle.zip - board and schematic files from Eagle

Test_CCS.c - simple tester - runs through all LEDs one at a time

Conway_CCS.c - Conway's game of life - includes a dual screen buffer - would be a good starting point for an app

 

***Assembly information***

post-1690-0-11055700-1364651087_thumb.png

Solder LEDs with the Anode (+) pointing towards the top of the board.

Transistors need to be soldered upside-down.  I'll fix this if I run another version of the board.

Shift register alignment is indicated on the board.  

LED Resistors are by column - so if you're mixing colors - make sure the whole column has the same voltage/current requirements - the number next to the resistor on the back corresponds to the column marking on the front.

LED_MatrixEnergia.txt

LED Matrix_V1_Eagle.zip

Test_CCS.c

Conway_CCS.c

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SMD soldering is not that hard, right? :thumbup:

Board looks great!

Nope - it's honestly not that bad.  Probably took me a little over an hour to solder, and partially because of the different LED colors I used.  A single LED color would be much easier.  I did manage to spill several of the transistors on the floor at one point though :)

 

If anybody is interested - I'm planning on doing a couple of kits with the extra parts I have.  Just PM me or post on the thread - they'll probably be going up in my Tindie store in a couple of days.

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BOM:

0805 or 0603 LEDs (64) - I used ones from DX.com - http://dx.com/s/0805+led+strip - but you can use whatever

LED Resistors (8) - depends on what LEDs you use.  Mine were between 33 and 100 ohms.
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I like soldering SMD better than PTH. For example when desoldering a TSSOP I manage much easier than desoldering a DIP with same pin count.

When etching your boards at home, using SMD has the big advantage of saving me a thousand drill holes.

Only drawback of SMD is that the realy realy dirty cheap chinese fabs may not be able to match the fine grain required for TSSOP packages and traces get shorted.

 

Did those green LEDs on the right light up on purpose, or is the picture bleeding into them?

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I have noticed a huge discrepancy between SMD green and blue or white LEDs myself.  I think on my F5172 LaunchPad board I used a 1K resistor for the green 3V3 indicator and a 2.2K for the blue 5V indicator, the blue is still way disproportionately brighter than the green, even if there is no 5V source (and the 5V net is being sourced by back-current from Vcc going through one of the components, thus making it lower than the Vcc voltage even...)

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I have noticed a huge discrepancy between SMD green and blue or white LEDs myself.  I think on my F5172 LaunchPad board I used a 1K resistor for the green 3V3 indicator and a 2.2K for the blue 5V indicator, the blue is still way disproportionately brighter than the green, even if there is no 5V source (and the 5V net is being sourced by back-current from Vcc going through one of the components, thus making it lower than the Vcc voltage even...)

How bright are they supposed to be?  Blue LEDs tend to be rated for higher MCD in my experience.  You can increase your resistor to drop the brightness, although 2.2K seems AWFULLY high.  

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I have no idea, and never bothered with the datasheets :D  But yeah, 5V + 2.2K = Still respectably BRIGHT.

 

On the bottom LEDs on my board I use a white one (which happens to also be super-thin in addition to being 0603, and a mild pain in the ass to solder cleanly) with a 220R with the blue next to it sporting a 1K.  Blue one gets good 'n bright on that (3.3V) but the white is downright blinding, especially with DVIO = 5V :D

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First batch of Kits and PCBs are available on my tindie store!  I added a discount code for 43oh members - DE65D57 - $1 off (will cover shipping in the US).

 

https://tindie.com/shops/cubeberg/smd-led-boosterpack-pcb-transistors/

https://tindie.com/shops/cubeberg/smd-led-boosterpack-kit-blue-leds/

 

Also - Conway's game of life implementation updated so it's much smoother and more efficient - moved the main code out of the interrupt - it's handled during wake in Main.  The code is a good start for using the device as a display.  I'll work on adding scrolling text in the next week or two.

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