Trinket with an OLED display

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jamesmunroe
 
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Trinket with an OLED display

Post by jamesmunroe »

I'm wondering if it's possible to use external memory of some sort, (like this i2c FRAM https://www.adafruit.com/product/1895) to help drive an OLED display (https://www.adafruit.com/products/931). I know that the display needs a 512k buffer, which is all the Trinket has to offer, so is external memory an option?

The application is pretty simple: a hiking altimeter. Basically just a Trinket, the MLP31152A sensor, a 150mA lipo battery, the OLED display and, I guess, ram for buffering the display. The nice thing is that all these components are i2c so the shortage of pins on the trinket is not an issue. The goal is to keep this as small as possible, so stepping up to a larger Arduino is not preferable.

I've checked out this post http://forums.adafruit.com/viewtopic.php?f=52&t=48928 so I think that what I want to do is possible, but that solution seemed overly complicated for the new arduino user that I am.

So, does anyone know if the i2c FRAM (or something else) would work to buffer the display? AND could anyone suggest how I might use the Adafruit GFX library with external buffering... That way I could at least order the parts and get started on this challenge.

Thanks!

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AnneBarela
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Re: Trinket with an OLED display

Post by AnneBarela »

The Adafruit GFX library is very code heavy for Trinket. I used it in the Trinket Occupancy Display tutorial but I barely had any additional room. Perhaps someone makes an I2C self-buffering display?

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michaelmeissner
 
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Re: Trinket with an OLED display

Post by michaelmeissner »

Dig-ole makes OLED and LCD devices that can be driven by serial, i2c, or SPI depending on how solder jumpers are set (default is serial). If you go i2c, there is a command to reset the i2c address if you have more than one OLED device. They ship from China and Canada: http://www.digole.com/index.php?categoryID=153.

I have the 0.96" OLED white display (128x64) and the 2.7" LCD. At the moment, I've only driven it via Serial from Ardiuno Uno and Teensy, but I would think it would work well on a Trinket or Gemma with i2c after getting the library code from digole.com and doing the usual Wire -> TinyWireM conversion, and deleting the code for handling Serial and SPI. I'm thinking of getting the 96x96 color display which would seem to be small enough to fit inside of a 16 LED neopixel ring.

On the 128x64 OLED device I have, there are 4 sizes of fonts: font size 6 is 32 characters x 10 lines; font size 10 is 21 characters x 7 lines; font size 18 is 14 characters x 4 lines; font size 51 is 8 characters x 2 lines. I find font sizes 6 and 10 to be too small for normal use, so I use font size 18.

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jamesmunroe
 
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Re: Trinket with an OLED display

Post by jamesmunroe »

Thanks for the replies! Seems like the trinket isn't going to work for this application, I might have to go with a 3.3v ProMini instead. Now I wondering if there's any battery life increase if I bypass the 5v regulator on the altitude sensor when powering via lipo battery...

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