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A project log for Pole Mounted Bus Tracker

The goal is to make an outdoor rated battery powered display that pulls data over cellular and can semi-permanently mount on a pole

Andrew SowaAndrew Sowa 04/29/2018 at 21:280 Comments

The first thing to do on the electronics side is too get a proof of concept working.  This is important to confirm that the idea is viable and figure out if any parts will drive the enclosure design. I can do this based on general ideas of what will work but in this case it will be best to layout what I want to accomplish with this project.  This will help you understand why I chose the parts that I did and give me a checklist to reference during the development process. 

Project Goals

Wireless Connection

I want to use cellular data on this project, specifically Hologram, for a couple reasons.  The biggest reason is that I don't think I can rely on WIFI or BLE.  I like very close to my local bus stop but I still can't see my home WIFI network. There is a coffee shop nearby, but not everyone is going to have that convenience. With cellular I know that most people will at least have signal.  

Hologram is going to be the choice to start mainly because I don't know enough about how Particle differs, they have a free tier, their headquarters is in Chicago, and I know people who work there. 

I picked the Adafruit Feather 32u4 Fona because Adafruit has a large reach to the community I am targeting.  This could be a custom PCB, but that would take time to develop and make things more complicated to start. I want to test a system right now and the more know working components I can get the faster I can get to testing system level functions. This was also the cheaper option than some of the other modules on the compatibility this here

Display

E-ink offers two advantages in this application.  It is easily readable in direct sunlight and only requires power when changing states. They have been being used more often in hobby projects because the cost has come done and they have Arduino library support.  Waveshare seems to be the de-facto brand at this time and should have enough documentation to get everything glued together. I bought a couple of the small sizes and the three color options so I can see which works best. 

Microprocessor

I am using the Atmel 32u4 because that's what the Fona board uses and it is Arduino compatible. If/when I make a custom PCB, I will need to think more about optimizing for cost, power, price, etc. but this will work for now.  

Battery

I want to work from a battery early in the project but I won't know what size I need until I do power calculations.  Once there is functioning code, I can measure power for different events and make a spreadsheet to calculate scenarios based on a variety of refresh rates. 

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