Repost: Sharp memory displays

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Martin
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Joined: 16 Feb 2018, 14:11
Location: Warwickshire

Repost: Sharp memory displays

Post by Martin »

Postby ceptimus » Mon Dec 11, 2017 8:25 pm

I'm working on a small LiPo battery charger / discharger / capacity tester project, mainly as a way of testing out a few modules I've got hanging around - a 1.54-inch e-Paper display, an INA219 current/voltage sensor, and a relay module.

I'll probably post about that project once I have it working but this post is just to draw your attention to a new (for me) type of display I came across while searching for code examples for the e-Paper display.

These displays are called 'Sharp memory displays' and are supposed to have the daylight readability and clarity of an e-Paper display combined with the fast refresh rates of a liquid crystal display, and the low power requirements of both types. These could be the perfect sunlight readable displays for projects like transmitters, where we want to use them outdoors, without the disadvantage of the quite-slow-to-refresh ePaper displays.

This 1.3-inch 168x144 pixel unit is available on Adafruit. It's a little pricey (25 US dollars) right now, but no doubt the price will plummet once they become popular and the Chinese start turning out clones.
3502-06.jpg


Re: Sharp memory displays
Postby ralkbirdy » Mon Dec 11, 2017 9:03 pm

Martin, will It do charge and discharge of 1s 10 - 30 mah cells, i am not sure what my tiny indoor cells are really like?

Re: Sharp memory displays
Postby ceptimus » Tue Dec 12, 2017 12:07 am


Hi Mike,
Yes. It's very simple with just two relays connecting the cell either to 5V via the current meter and a current limiting resistor for charge, or connecting the cell through the current meter and a current limiting resistor to ground for discharge.

By choosing the resistor value, you can set the charge/discharge current to be anything you like - from a few milliamps up to an amp or more. Obviously it needs a power supply for the higher charge currents - I'm using an old mains adapter that puts out about 8V at up to 2A and the gadget has a voltage regulator. The resolution of the INA219 current sensor is better than a one milliamp and can be set to an even more sensitive range if you only ever want to work with tiny batteries. My gadget has a little fan to keep the power regulator and high-wattage resistors cool but if you're only working with small batteries that wouldn't be necessary.

It has options to charge, discharge, cycle, or bring to storage charge.

I'm programming it to display the voltages and currents, elapsed time, charge / discharge graphs, measured cell capacity, and so on using an e-Paper display - these displays have the advantage of retaining the last information displayed even after you switch the power off. I suppose I could tweak the sketch to work with other cheaper displays if you don't want to buy an e-Paper one.

Martin.

Re: Sharp memory displays
Postby FBMinis » Tue Dec 12, 2017 10:22 pm


I am looking forward to your project, as it seems the most complete of the arduino capacity testers I've seen around,like:

http://www.instructables.com/id/DIY-Ard ... ster-V10-/

I would use it to test cellphone batteries and 18650 I have been gathering from laptops.

Actually, my tablet started to shutdown just a few moments after I unplug the transformer, even though it displays 100% charge and over 4.1V in CPU-Z app. If I let it OFF for some minutes, it turns ON and shows close to 100% but shuts down again. Not sure if it's a problem with the battery, calibration or sensor. The battery has 7 wires and a small connector (2x red; 2x black; white, yellow and blue). I would like to assert it's real capacity before venturing on buying a replacement.

https://www.ebay.es/itm/Bateria-Tablet- ... 2672054735?

Re: Sharp memory displays
Postby _AL_ » Sat Dec 30, 2017 4:15 am

The displays look interesting.
Hopefully once the Chinese get hold of one they make a smaller version like the little Oleds. They would make great replacements for the old Kraft black & white meters.

Al
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