LED-Board 4x4 16bit

a LED-Matrix Board that can be combined seamlessly to bigger areas.
It uses the TI TLC5971 Constant-Current LED-Driver Chip with 16bit dimming resolution.

The original LED-footprint was for Nichia NSSM032A RGB-LED. Back in 2017 on of the brightest low power SMD LEDs in this size - They are only available as full reel directly from Nichia.

so there is a second branch with the LED-Type changed to Nichia NSSM124D - these are available as cut-tape from an distributor.

latest addition is a branch with TLC5971PWP driver chips - this is the same chip but in an HTSSOP-20 housing - that is easier to solder by hand. --> no hot air / reflow oven necessary, but recommend.

Project-Status

• received first Batch (Release V1.0.0)
• received second Batch (Release V3.0.1)
• 11 PCB's assembled
  10 working 🌞
  first solder board not working - has a short between VCC and GND (to be checked)
• all needed heavy rework: stencil has to big openings - this gives a bunch of bridges at QFN 0,5mm Pin-Pitch IC's
• had some problems with the first reflow oven used - you need enough heat from the bottom to solder correctly.
• made some picture from first assembly: gallery
• fix pads that are to small for hand-soldering done
• order updated PCB's done
• solder some more boards done (total: ~60)
• order screws at Wegertseder done
• updated KiCad files to new version.

TODO

• order Heat Sink with machining and Thermal Foil from Fischer Elektronik
• add some more mounting layouts to LEDBoard_Layouts
• take some more pictures

Technical Information

there are groups of 4 LEDs that are controlled by one TLC5971.
every controller chip has 12 ConstantCurrent outputs. so every LED is controllable individual.

you need to create a mapping to linearize the order:

X/Y	0	1	2	3
0	IC1 LED1	IC1 LED2	IC2 LED1	IC2 LED2
1	IC1 LED3	IC1 LED4	IC2 LED3	IC2 LED4
2	IC3 LED1	IC3 LED2	IC4 LED1	IC4 LED2
3	IC3 LED3	IC3 LED4	IC4 LED3	IC4 LED4

example for c++ / arduino

const uint8_t channel_position_map[4][4] = {
    { 0,  1,  4,  5},
    { 2,  3,  6,  7},
    { 8,  9, 12, 13},
    {10, 11, 14, 15},
};

HW

• PCB size: 40x40x18mm
• pixel-pitch: 10mm
• 3.8V..5.5V
• <= 1A (maximum)

BOM

there is the raw exported BOM at export/BOM/LEDBoard_4x4_16bit_BOM.csv and an modified LibreOffice Calc file with ordering and Price calculations at doc/LEDBoard_4x4_16bit_PriceCalculation_Ordering (link points to exported csv as preview)

controlling

Micro Controller / Arduino

there are some Arduino Libraries out there that can generate the correct protocol. My Favorite is ulrichstern/Tlc59711

i have made a simple arduino sketch that uses the mentioned library to test the Boards during production.

embedded linux boards

Additionally you can use a embedded Linux board with an SPI output to drive them. I have successfully implemented the protocol in my fork of OLA. (TODO: Link and explain OLA setup)

there are also other python libraries out there. (TODO: test some of theme and link here)

power & signal connections

theoretically calculate with about 1A@5V for every Board. Supply Voltage (VCC) should be 3,8V..5,5V - If possible use the lower end. so no extra heat is generated in the driver IC.

for the control-signal there are an input and output 3pin 2,54mm connector:

1. Data
2. Clock
3. GND

for the power there are 3x2pin 2,54mm connector positions. so you could daisy-chain power also - but be aware the pcb-traces can handle an absolute maximum of 3,5A. So i would recommend only 1 or maximum 2 daisy-chained boards.

KiCad Version

Application: KiCad

Version: 5.99.0-unknown-652a59b78~104~ubuntu20.04.1, release build

Libraries:
	wxWidgets 3.0.4
	libcurl/7.68.0 OpenSSL/1.1.1f zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh/0.9.3/openssl/zlib nghttp2/1.40.0 librtmp/2.3

Platform: Linux 5.4.0-48-generic x86_64, 64 bit, Little endian, wxGTK

Build Info:
	Date: Sep 16 2020 10:16:55
	wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.71.0
	OCE: 6.9.1
	Curl: 7.68.0
	ngspice: 31
	Compiler: GCC 9.3.0 with C++ ABI 1013

Build settings:
	KICAD_SCRIPTING=ON
	KICAD_SCRIPTING_MODULES=ON
	KICAD_SCRIPTING_PYTHON3=ON
	KICAD_SCRIPTING_WXPYTHON=ON
	KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
	KICAD_SCRIPTING_ACTION_MENU=ON
	BUILD_GITHUB_PLUGIN=ON
	KICAD_USE_OCE=ON
	KICAD_SPICE=ON

License

LEDBoard_4x4_16bit by Stefan Krüger (s-light) is licensed under a Creative Commons Attribution 4.0 International License .