The SparkFun Large Digit Driver is a chainable controller backpack that can be soldered directly to the back of our large 6.5" 7-segment displays. Large numerical displays are a great addition to any project where you want to be able to see information at a distance. Scorekeepers and lap timers would be a great application for large 7-segment LED displays.
The SparkFun Large Digit Driver can easily be attached to the back of the 7-segment display by soldering all 10 castellations pins at the bottom of the board as well as the two additional castellations at the top. Keep in mind that the Large Digit Driver requires both 12V for the LEDs and 5V for the on-board TPIC6C596 IC. Each driver is equipped with six input pins and six output pins, these make the driver capable of being chained together. The input/output pins are listed as GND (Ground), LAT (Latch), CLK (Clock), SER (Serial), 5V (Power for the driver IC), and 12V (Power for the 7-segment display).
The Large Digit Driver has 8 inline 15 Ohm resistors to limit the current through each segment on the 6" display to 20mA (as dictated by the display datasheet). You will need approximately 160mA of current at 12V for each digit in your display.
We used the SparkFun Large Digit Driver in our AVC Battle-Bot Arena to display times and scores!
Take extra care to note the placement of the 5V and 12V pins. They are right next to each other, and we have seen instances where 12V was accidentally applied to the 5V line. This will not end well. It will usually wind up frying the microcontroller, resulting in a nonfunctioning board, and possibly tears.
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If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.
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This seems to be a workable driver chip for the large 7-segment displays. However, the enable pin is hard-wired, so most of the time when powering on the unit, all of the segments are lit. Also, when powering on, they appear to “lock up” the arduino until the reset button is pressed. I have tried adding delays of several seconds on on startup, and isolating the 5V supply (not using the arduino 5V out), but they still require a reset. Lastly, because this is just a basic shift register and doesn’t do PWM, the brightness of the segments varies depending on how many are lit at one time.
Sorry to hear about the issues with getting the 7-segments working. Have you contacted our technical support department @ firstname.lastname@example.org - they’re usually great at getting devices working.
I used six of these with the giant 7-segment displays to make a giant clock for a large meeting hall. They do exactly what they are supposed to do.
I’m building a “cash booth” for my company, where we put the “employee of the month” in a booth with a couple hundred bucks and watch them flail around for a bit. We use these large digits (and the driver boards) for the timer mechanism, and they’re a huge part of making the booth look “legit”. Programming them using the given examples was probably the easiest task outside of making the buttons work. If you have a project where you need people to see a big number from 100+ feet away across a crowded room, this it the way to go!