Low power, seven segment display

Question

I want to display a 4 digit number on a small device that fits in a hand. I have a CR2032 3V battery at around 230mA, my microprocessor is a 8051 (in a BLE112) usually uses about 0.9µA and I want the device to last as long as possible.

I've looked at the typical seven segment displays, which typically uses a few mA which is too much.

A alternative is the Sharp LS013B7DH01 which is used in Pebble and uses 5 µA, but seems a bit complex for my microprocessor (and expensive)?

There should be some simple low power 7 segment display which has a average power consumption measured in µA (not mA), but I simply can't find it or think of some other solution.

What alternatives do I have?

How often does the value change? – Ignacio Vazquez-Abrams Oct 11 '13 at 09:20 — Ignacio Vazquez-Abrams, Oct 11 '13 at 09:20
When in use, a few times per minute – Hink Oct 11 '13 at 09:37 — Hink, Oct 11 '13 at 09:37

score 12 · Accepted Answer · answered Oct 11 '13 at 09:10

12

LCD display without back-light is the only possible solution on these conditions.

Something like this:

enter image description here

Here is some example data sheet: Link to PDF

answered Oct 11 '13 at 09:10

johnfound

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Nice, how much energy would it use? – Hink Oct 11 '13 at 09:36
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@Hink - probably several uA. – johnfound Oct 11 '13 at 09:37
How would I drive it with a 3V (DC) coincell battery in a power efficient way? I found out that I need some separate driver chip which can alternate the current. Preferably I would like to just input numbers via SPI, I2C etc. – Hink Oct 22 '13 at 16:22
@Hink - with programmable unit as a uC you can control it in whatever manner you want. For 4 digit number you will need 7+4=11 outputs. – johnfound Oct 22 '13 at 16:44
But every LCD display I could find uses AC. As I understand it, all need some controller to alternate the current for it to work with DC? Is there a tutorial using a LCD segment display like the one you show in the picture? – Hink Oct 22 '13 at 17:09
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@Hink - but you can generate AC with the outputs of the uC. But IMO, how to do so is a little bit offtopic in this answer. Maybe you have to ask another question about how to control LCD display. – johnfound Oct 22 '13 at 17:12
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Note that you need a minimum of 1 + (7 * 4) = 29 outputs to drive a static 7-segment 4-digit display (no decimal points or colon) as in the linked datasheet. One output drives the backplane (common) plus you need one for each segment. – Spehro Pefhany Oct 23 '14 at 20:49
@SpehroPefhany Can't shift register help this? – kando Sep 07 '16 at 17:01

score 4 · Answer 2 · answered Oct 11 '13 at 09:38

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E-paper displays "stick" at the last value displayed, and only use power to change: http://www.eink.com/

They're a bit of a hassle to drive, and expensive.

answered Oct 11 '13 at 09:38

pjc50

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score 0 · Answer 3 · answered Oct 16 '13 at 07:08

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Sarkfun used to sell a small E-paper display. https://www.sparkfun.com/products/retired/10150

Perhaps you can locate a different widget vendor for the same.

answered Oct 16 '13 at 07:08

lithiumhead

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SeeedStudio has these: http://www.seeedstudio.com/depot/small-epaper-shield-p-1597.html http://www.seeedstudio.com/depot/eink-display-shield-p-1374.html – lithiumhead Oct 16 '13 at 07:11

Low power, seven segment display

3 Answers3