Hello,
I need to create a 16 character digital nameplate for a project at work. I think I have a plan of attack firmly in mind, but I want to get knowledge from the EEVblog community in case any of you would like to share your experiences or part preferences.
The basic requirements:
- 20 single color alphanumeric characters.
- Scalable solution preferred; 5 daisy chained 4-character modules, for example.
- Must be able to change the message remotely. (Bluetooth LE, WiFi, whatever, not necessarily wireless. Preference for simplicity in terms of hardware required.)
- Message does not need to remain after a power failure.
- Message does not need to scroll; no fancy effects required. Just display some text.
Drivers:
At first I looked at the MAX6953 (since I have a few on-hand) but I ordered LED 5x7 matricies which are not compatible with that Maxim chip.
The Maxim 7219 and 7221 seem pretty expensive, I think I could probably do better with a small micro behind each character, creating single 5x7 matrix modules. I would drive single LEDs at a time in this scenario, not entire rows or columns; I think this will help keep brightness uniform, if I can switch between LEDs quickly enough.
LEDs:
I found some matrices on Jameco for $0.99 each in a closeout, and ordered a ton of them. These are the matrices that are not easily driven from the MAX6953s I have on hand.
I could also just buy a pile of 0402 surface-mount LEDs and design the circuit board appropriately.
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If anyone has any experience with this stuff (mikeselectricstuff...), and you don't mind doing so, please chime in with a bit of advice... This is just a one-off prototype that I'll design and assemble myself. Don't put a lot of thought into mass production.
If the best option would be to just buy one, that's fine. I'd prefer to do some PCB design and solder work, but if there is a finished product that is Just Great, then please let me know.
Budget is USD$200 or less for parts.