Microcontroller User Interfaces

The intent of this page is to document different styles of user interfaces for microcontrollers together with code ( any language ) to drive them. We could use some contributions, can you help?

Input

Momentary Button

• Pro Cheap, simple, uses only 1 bit port
• Con If you use a bunch uses a lot of port bits

Rotary Switch

• Pro
• Con

Can be self decoding: position of switch indicates state of microcontroller.

Rotary Encoder

• Pro
• Con

Potentiometer

Use to feed a voltage to an analog to digitial converter. You sould be able to get quite a few discrete values out of this while still having it easy to use. Instead of a pot you can use a rotary switch with fixed resistors switched.

• Pro Uses only 1 pin if using an AtoD converter.
• Con Readint takes a AtoD converter ( or standard io port(s) with software. Takes a bit of time.

Keypad

• Pro
• Con

Output

Single Led

In its simplest form either on or off, slightly harder to read are various patterns of blinks.

• Pro
• Con

Multiple Led

• Pro Cheap, simple, easy to drive. One port bit per led ( untill you get to large numbers where ticks kick in ) Match with a pushbutton and state of the microcontroller and means to change it is simple.
• Con Can use more port bits than you have.

A shift register can make driving a large number easier.

7 Segment Led

• Pro
• Con

LCD

In the nibble mode mode needs a total of 7 port bits. Some displays are backlit, others are not.

• Pro Can have lots of characters, small displays are often 2 x 16. Cost is about 10 bucks.
• Con Cost is about 10 bucks. You may not have the 7 port bits available.

PC on Serial Port

Control with a terminal program or a custom application. PC provides both input and output.

• Pro 2 bit only. Can have very fancy smart interface. Can be very useful for debugging.
• Con Needs PC. May need custom application. For good flexibility needs a uart on the chip.