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Thread: 7 segment LED display with Teensy 3.6

  1. #1
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    7 segment LED display with Teensy 3.6

    Looking for tip how to interface 7 segment LED display with Teensy 3.6.

    Project are a rebuild with existing user interface with several common anode 7 segment LED displays and a 4x4 LED matrix which need both source and sinking.

    Initially I hoped to find x4AHCT chips to do this, but those Iíve encountered donít have the capability to drive LEDís much better than the MK66.

    Old 5V LED driver circuits suggest current draw needed for LED's used on the panel are around 14mA.

  2. #2
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    Because of the number of pins needed to sink/source more than 10mA project moved to ATmega2560. But found SN74F chips might work with T3.6 as it has 2V high level and can sink 3 to 4 times what the K66 can.

  3. #3
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    Hmm, looks like my responce vanished. Yes, the current both per pin and per device would have been an issue with direct drive, though possible using a lower spec micro as a smart driver would be an option. The MAX series of driver ICs may also do what you want https://www.adafruit.com/product/879

    See also https://www.pjrc.com/teensy/td_libs_LedControl.html

  4. #4
    The simplest way is to use a 7 segment driver chip between the Teensy and the 7 segment display module: https://www.digikey.com/products/en/...=1&pageSize=25 -- this requires 4, or at most 5 pins with the 5th one being 'enable'

    A more complicated way is to drive it directly -- you need to do all the decoding, plus it requires at least 7 pins. Unless cost of the finished product is an issue (say, you want to make a million * * ), I would normally go with the 7 segment driver chip.

  5. #5
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    Thanks guys.

    I forgot to mention it needs to be through hole devices. Didn't find any of the usual 7 segement suspects in the x4AHCT family when I first looked.
    But the MAX serien might work with 2V high level?

  6. #6
    Senior Member bmillier's Avatar
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    The 74ls47 will work. It's not the cheapest option, but is Thru hole.
    https://www.digikey.ca/product-detai...12-5-ND/377730

  7. #7
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  8. #8
    Quote Originally Posted by CanIdoIT View Post
    I forgot to mention it needs to be through hole devices. Didn't find any of the usual 7 segement suspects in the x4AHCT family when I first looked.
    The link I posted above has 8 through hole devices. For a single 7 segment display, you probably want either the SN74LS47N or the SN74LS247N from that list, both under $1.80 apiece.

    But there might be other, cheaper options like the CD45111 posted above.

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