I have decided this winter I am going to make a 8’ electronic scoreboard for my kids football team. I have seen some different examples on how the 7 segment displays work but I am confused as how they are wired all together and how many wires go back to the arduino.
I have a spare Mega that I will be using for this project.
Here is the parts list that I am planing to use.
12 Volt Power supply
Mega 2560 V3
Roll of Cat 5 cable for wiring
LED Type: 5050 SMD 12v
I bought the RGB version because I thought I could use just one color for Scores, and Quarter. and I was thinking that when the clock changes to the last minute go from white to red for the seconds count down.
9 leds per segment (total of 63 segments)
Time 4 *7 segment
Home Team 2 * 7 segment
Away Team 2 * 7 Segment
Quarter 1 * 7 segment
63 N-Channel Power MOSFET transistors + 14 more for the time color change (but I am not sure which ones)
now I am not sure which shift register (or if that’s the proper name) I should be using and how to have all them connected.
is it the TPIC6B595 and would I use one for every seven segment digit? and can have them daisy chained together, and what is the max amount of them I can use together.
Thanks for the info, so I am assuming I will need 11 74HC595, and use one chip per 7 segment display. (main clock will have an additional two so I can do the last minute count down in a different color.
There is a chip on the market( OF cannot recall the part #, sorry) which will control 8 x 8 LED matrix individually ( latched outputs and some limited intensity control ) using serial data
It may simplify you hardware.
It was mentioned on few posts here.
If interested I'll try to locate the part #.
MAX7219 will need lots of components to drive high voltage & current.
Other versions of TPIC6x595 can drive higher currents, up to 350mA.
TPIC6595 for instance can sink 250mA continuous from a 45V source.
If you can wire the LEDs in series so you have say 15-20 LEDs in series all sharing 20mA from 45V source, and make each segment from say 4 strings (arranged physically as 2 long by 2 wide, so it looks like 2x40), then each segment needs only 80mA and TPIC6B595 would be fine, use 1 for each digit.
I offer a board that can sink current for up to 12 digits; the 45V+ would connect to the LED +and the 45V Gnd would connect to the board Gnd. It has a '328P chip for arduino functionality. An offboard FTDI Basic or equivalent is plugged on for serial programming. IO pins let you connect buttons, an RTC module, etc. Cross Roads Electronics scroll down about 2/3 of the way
I found it the Max7219 they show it controlling 64 led's with one chip, that's awesome. thanks, I think I might even have one with the kit I bought.
Thanks so much, I will check it out.
You can control 64 leds/segments (8x8) with just 16 pins, but it comes with another cost as well.
While displaying, only 8 leds (1 row/column/number) max will be on at the same time. By displaying rows/columns/numbers fast enough after each other it seems... like all 64 leds can be on at the same time, but that's not the case.
It's our Persistence of vision that makes us believe they're lit constantly.
If you would use a chip/solution like this, individual segments will only be lit 1/8 of the time. As a result your scoreboard will be far less visible as possible.
Sorry, got a little lost in the discussion.
Looking at these #s:
Working power 30leds/m:4-5W/M
Working Current 30leds/m:1.7-2.1A/5M <<< Which do you have?
60leds/m:3.7A-4.2A/5M <<< Which do you have?
you’re gonna need a hefty power supply.
These currents come about because there are 3 LEDs in series every so many inches, and every 3 LEDs is in parallel with the others. TPIC6x595 can’t sink that much current.
You need a board like this for that much current. This has AOI516 or AOI518 N-channel MOSFETs with bases controlled by 74HC595 shift register, an Arduino is used to shift data in to be displayed.
Board is designed to be daisychained, so two boards for 64 segments. I only planned for 1A/transistor on these, so likely extra wire would be needed to added to the traces to beef up current capability. If you have MOSFETs already, we’d need a part number to see if they are logic level; or standard, which need 10V swing on the gates to fully turn them on/off.