Using the Nokia 5110 LCD with the fewest system resources

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I had a project that needed some live data display, and looking for the cheapest low-power solution for our loggers lead me to the Nokia 5110 LCD. Once you get the backlight current under control, you can power the entire display from a digital pin, and if you use shiftout for soft SPI you can then get rid of the Reset and CSelect control lines. This brings the display down to any four wires you can spare on your build (incl. the power pin) and a ground. This is much more manageable than what you see with the standard hookup guides if your mcu is I/O limited like our pro-mini based loggers:

 

Adding the Nokia 5110 LCD to your Arduino Data Logger
https://thecavepearlproject.org/2018/05/18/adding-the-nokia-5110-lcd-to-your-arduino-data-logger/

- The Cave Pearl Project: Developing Arduino based underwater data loggers and sensors -

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Just wondering what made you use soft SPI over the real peripheral? Just seems a step backwards when Arduino chips have it in the silicon.

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I use the hardware SPI lines for saving data to SD card, and I don't want to mess them up with slow LCD coms. Also, since I already have an SPI device on the build, I can't get rid of the CSelect wire by tying it to ground. Depowering the screen is also a priority, and I'm not sure how that would affect the SD cards on the same hardware lines.

 

So basically everything on our wish list is easily accomplished if you do not use hardware SPI

- The Cave Pearl Project: Developing Arduino based underwater data loggers and sensors -

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I am not sure it is wise to ignore the Reset\ line.

 

It is a great little display, and I've used a bunch of them, but it does have a rather specific setup process if one wishes to abide by the data sheet.

 

JC

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I've had terrible luck with Nokia 5110 screens.  Each unit's contrast value depends on how the physical parts and frames are pressed together in the manufacturing process.  The contrast will often change according to how you hold the unit.   I found it impossible to use them consistently and reliably.  Nevertheless, they are cheap, low-power, and [relatively] easy to use.  I find that paying an extra dollar or so per unit for a ST7735-based TFT screen to be worth the extra expense.

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To be honest I though it would fail too, but I ran a test batch with four units through almost ten thousand power cycles and they all worked fine (two different screen suppliers). I think the only reason it works is that I am doing a hard power down via the pin powering. So the controller really does not have a any choice about going through a reset.

 

I currently have a couple of loggers with this screen method running long term tests in a cave, cycling power to the screen 96 times a day.  I will report the results of those real world tests in a couple of months. For my data logging application power was the single most important factor in the choice of screen - everything else was secondary.

 

 

- The Cave Pearl Project: Developing Arduino based underwater data loggers and sensors -

Last Edited: Sun. May 27, 2018 - 11:34 PM
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ekmallon wrote:
For my data logging application power was the single most important factor in the choice of screen - everything else was secondary.

 

What currents did you achieve with this display ?  Did that vary much by supplier ?

 

Did you look at the more advanced low power LCD displays like Sharp - or are they too expensive ?