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A project log for Raspberry Pi Glucometer

A programmable glucometer powered by a Raspberry Pi Zero

jonathan-buchananJonathan Buchanan 12/07/2016 at 16:410 Comments

I'm not dead, though progress has been slow.

I have done a lot of work, but not enough on any specific thing to merit its own update, so I decided to do a combined entry.


Software

A large portion of what I've done has been small additions and improvements to the code. The data screen now sorts entries, the delete and edit buttons now work, and a lot of background cleanup. I've also started to experiment with fixing the size of the keyboard,

too small (and qwerty)just right
and adding better selectors for dates and times.Other than these things, there is not much more to see on the software side of things.

Hardware

I bought and setup a real time clock (RTC).

The RTC is a microchip that is constantly powered by a small battery. All it does is keep time for the computer even when it is off or the main battery is totally dead. Using Adafruit's libraries it was easy to set up so the pi updates its hardware clock from the RTC when it boots.

Speaking of adding new PCBs, this protype is made up of a total of 6 individual PCBs:

I have started preliminary work on combining the last four so into one big PCB for more compact space usage and the possibility of producing these to sell eventually. This is possible because all of Adafruit's PCB designs are open-source, but still difficult since I am unfamiliar with Eagle.

It has also become painfully obvious that the raspberry pi zero is not capable of running opengl like kivy requires. The whole system takes 60 seconds from power to ready-to-use to boot, and there is lag while switching in between screens. I tested the Pi 3 (a much more powerful device) on my 2000mAh battery, and it ran for more than an hour of continuous use. Though that may not sound like much, I probably use my current meter for less than 5 minutes a day of continous use, and the glucometer program runs silky smooth compared to the zero.

I believe I will have to switch to the Pi 3 to get the speed I need, and I'm going to play around with buildroot to try to optimize the boot time even better (still takes almost 20 seconds on the Pi 3). I will probably also have to put the battery underneath the pi, instead of between in and the screen, which will add 1/2" to the thickness of the device :(.

Case

The progress on the case has been proceeding slowly and simultaneously with the other projects, but I have a first draft faceplate. The model was made primarily by Samantha Maness, a classmate who is planning on studying matierals engineering.

The model appears to be good, but I wasn't able to test fit it because the x-axis was out of alignment on the printer.


Today I hope to re-align and print again, so expect an update on that soon.

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