i got some 7 segment displays with higher voltage rating. i want to multiplex 4 digit and drive them from spark core. The issue is their voltage rating is 7 to 10 volts, Datasheet ( http://www.kingbrightusa.com/images/catalog/SPEC/sc40-19ewa.pdf). Want to create a digital clock with spark core.
i have very little knowledge about electronics and trying to learn with Spark core.
Thanks and Regards
You need something like a driver/buffer.
I used ULN2003 in the past http://www.ti.com/lit/ds/symlink/uln2003a.pdf but years ago so maybe i did the wrong thing
@bmishra4, check out this similar topic:
For starting off if you did not want to dive in to figuring that out, you could go with something from adafruit with a backpack. http://www.adafruit.com/categories/103 $9 - $12 connects I2C and everything is done for you. Its pretty nice and their libraries port over very nicely to spark core. I am sure you could find someone has ported it. I have a small port of their library where I left only the 7segment code. https://github.com/SomeFixItDude/MegaStat/tree/master/Thermostat
If your new or didn’t feel like being bothered figuring out how to drive that display the above is a great alternative. Starting out you probably want to dive in to coding, making classes and figuring cool dings and whirly noises to torture you (I mean wake you up) in the morning. Lol or make you play simon says to turn off the noise.
I know you said you are a beginner, so I’ll apologise in advance if this is not too helpful to you, but I am a big fan of the TLC59282 from TI. There are approximate equivalents from many other vendors. I have used these to drive Kingbright SA40-18EWA displays with great success. This was not a based device, though - so I have no design to share that you can simply use.
If you feed the LEDs with 9-10V, everything stays nice and cool. Because the TLC59282 is a constant current device, the segments on the display are uniform brightness.
Watch out for the decimal points though - they take half the current (I rotated one display and wired them in parallel so they were a flashing colon between the HH and MM digits in my design. When you wire two of them in parallel, they take the same current as the other segments.)
Here is something similar, not constant current, and inferior to the devices like the TLC59282, but it’s done and ready to go, which is almost always a good thing.
Thanks everyone for your valuable suggestions, i appreciate your promptness and always open to share the knowledge.
did some google and found https://www.tindie.com/products/rajbex/serial-driver-for-large-seven-segment-led-display-modules/
unfortunatly they don’t deliver in Singapore
You’re in singapore? Good to know there’s people messing with cores
If you need help locally, just @ me!
Can you confirm that you only need 4 digits ?
I’ll see if I can accelerate a simple 4-digit driver based on the TLC59282.
It would have two 20-pin (2x10 0.1") connectors for the LEDs, and a loop-in/out section for connection to the micro or . It’ll be on OSHpark, if I order 3, I can send you one. It would have a mix of surface mount and through-hole construction, but nothing stupendously difficult. it would be no sooner than a month before you could have that PCB, I’d guess (delays with me doing the layout, 12 days @ OSHpark, then US->Singapore shipping.)
Thanks a lot AndyW,
yes you are right I need driver for 4 digit common cathode only. Many thanks for helping me. If possible kindly send me two.
Your efforts and help is highly appreciated.
Well, I can probably send you one.
If you like it, I’ll share the project on OSHpark, so you can order more for yourself.
Many Thanks AndyW, you are so helpful. as you said will order the additional boards from OSHpark.
please feel free to let me know the needful from myside.
Thanks and Regards