Working with shift registers (tlc5940 and Library) on Sparkfun breakout boards driving individual LEDs.
The boards are designed to connect VPRG, GSCLOCK, BLANK, XLATCH, SIN/OUT, SCLK,VCC, GND in serial. Everything works perfectly on Board #1-10. However, I need quite a few more boards/chips (up to 28) and the signals get crazy from Board 11 onwards.
I was hoping to find some options to increase the signal strengths to and past board #11, all while keeping the timing correct.. Any help with possible solutions/specific schematics is GREATLY appreciated.
The TLC breakout boards are spaced every three inches. LEDs, chips and Arduino all are powered from a 5V regulated, 40amp source (MeanWell). Power is getting to last board and it's Leds. The connections/soldering are solid and not shorting. Each led and board has been tested individually.
I understand that this is a tall order, impedance, connections, conductance, the board, etc are in play here but I very much need to keep the boards in this lengthy configuration (necessary for art installation). Even if this boost doesn’t get all 28 chips working, I’d like to understand more how the various clock, latch, data signals can work through an extended serial bus and what I can do to clean up, bolster and push them further.
Chip Datasheet: https://www.sparkfun.com/datasheets/Components/General/tlc5940.pdf Spark fun Board: https://www.sparkfun.com/products/10616
EDIT: ROUND TWO
Hoping the break from this project doesn't bury it, but I've got a few more questions based on trying to use the above suggestions.
I've redesigned the art installation so that I could get the chip/boards centralized and next to each other/Arduino rather than separated out to the 4 grids of LEDs. I am going to run a much, much thicker solid straight line for connections, ground and power (which I will increase to 6v). Main question I have is about the difference between a Buffer Amp and the clock driver. Since the TLC5940 boards are designed to run in serial, and since I need so many (approx30), It's been suggested that I run a 74HC7014 Non-invert amp every three-ish boards. I can do that, but should I drive all of the signals from the same Buffer? Data, VPRG, Blank, and both clock signals (GSclock, Sclk)?
Or should I push both clock signals in parallel from a "robust" clock driver (any suggestions as to which one?) and the rest of the signals in serial through the boards and Buffers?
I was also wondering how and if I need to do anything to terminate any of the signals/ground? Would it help keep everything working as supposed? Right now, all signals/power and ground are just in a long line, from the Arduino straight through all boards and drivers (It does bend in half, though, to keep it compact) Is there anything that should be done after the last board? Or can they just end?
Could use a little more suggestion on the schematic before I solder this up and try it out. @oldfart ?