Morning all,
Working on smart card system and I'm looking to simplify system. Have it working like I want.
Arduino Uno
DS3231 clock
MFRC522
LCD 16x2
GSM 800L
Is there any options out there that can get me down to uno and one or two shields? The simpler, the better. My prototype case looks like a family of octopi in there.
If you use an I2C backpack for your LCD display, you can connect the display with just 4 wires (including power) and can use duPont connectors instead of a shield. The clock module requires only 4 wires so can use duPont connectors.
Don't you need a level shifter also for the MFRC522 reader ? The basic chip is not 5 volt tolerant.
True simplification: ditch the Uno and the shields.
Grab a piece of perfboard, get a Nano, and solder it all up. Of course after you tried out the circuit on a breadboard so you know it's good.
Indeed I2C backpack for the display is the way to go. I've never even been willing to try it without, and not just because it'd take up all the IO pins of a NodeMCU 