Hello, I'm working on a photoplethysmography (PPG), thermometer and stopwatch circuit for sportspersons to measure heart rate, core temperature and lap times. Ideally I would like to show this information on a small LCD display. However, I have never used an LCD display before.

The temperature will require 5 characters: i.e. 35.5C
The stopwatch will measure up to 1/10th of a second and so require 7 characters i.e. 59:59:5
The heart rate will require 6 digits i.e. 140bpm

I am using a 5V supply and the unit is supposed to be portable (used in the gym).

1.Which LCD displays and MCUs would be most suited to this purpose?
2.How easy are LCD displays to program (relative to 7-segment displays)?

 

Typically LCDs of this type are custom made. You are going to have a hard time finding something in the form factor you need and the number of characters needed.

Remember you will also need characters to signify functions and units of measure. In a custom display, this would be done with small symbols and custom lettering.

 

Displays come in 3 main forms: complete custom, standard alphanumeric, or graphic.

Custom is custom, money and time to get even one. You'll need something custom to drive them too, up to one micro pin per element on the screen.

Standard alphanumeric come in sizes from about 1 line of 8 characters to 4 lines of 20 characters, or more. They are not that hard to get to work with a handful of micro pins.

Graphic is really cool and can have touch overlays for not much money. Interface can be as simple as alphanumeric. Programming is fairly involved even using standard libraries.

Here's my favorite EBay source for displays.

 

But can you find a graphic display small enough to be useful (I would assume wearable) but still provide the resolution needed?

Most graphic displays I have seen that can be easily interfaced are fairly large.

I suppose a Nokia phone type display would be a good choice but I understand they can be a challenge to interface?

 

A standard 2x16 Character LCD is common and relatively inexpensive.
Writing your own library is straight forward once you know what to do.
Once you have gotten over this hurdle there is no looking back and it becomes a non-issue.

 

From the back of head. I think I have seen graphic LCDs modules at www.sparkfun.com. With all docs needed and sample code also