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Logger Mini Refinements

I’ve made some refinements to the Backcountry Logger firmware, based on my experiences in the field last weekend. I’ve decided to bring the Logger Mini with me on my upcoming John Muir Trail trip, rather than the Logger Classic that I brought to Mount Langley. The Mini (shown here) is smaller, lighter, and has a higher-resolution screen than the Classic. Earlier I was concerned about the durability of the Mini, but I constructed a fairly rugged carrying case for it out of a dental floss container!

The biggest problem I had on the Langley trip was accidental button pushing while the logger was in my pocket. The first photo shows my solution to this problem: both the PREVIOUS and NEXT buttons (but not SELECT) must be held in order to unlock the device when awakened from sleep mode. I also got fancy and threw the BMOW logo onto the unlock screen for fun. So far this approach to unlocking seems to have conquered the random button pushing problem nicely.

The extra resolution of the Mini’s 128 x 64 displays really helps the graphs — they look much cleaner than with the Classic. I boosted the OLED display brightness to the maximum, but unfortunately it still looks washed-out when viewed in direct sunlight.


The Mini has a SQ-SEN-200 omnidirectional tilt/vibration sensor, which the firmware uses to detect movement. If there’s movement for four consecutive minutes, it concludes you’ve begun a trip, and starts the trip timer. After 6 consecutive minutes with no movement, the trip timer stops. In practice the movement detection with the SQ-SEN-200 works very well, but the time thresholds may need to be tweaked. The 1:19 trip shown here was my walk down the hill to the store and back.


To protect the Mini, I built a storage case out of an old dental floss container. I cut off the lower half of the container to reduce its height, and then hot-glued a plastic scrap over the bottom opening to seal it. The resulting case is very sturdy, and fits the Mini perfectly.

The firmware now almost completely fills both the program and data memories on the ATmega, which I think is my clue that development is done. Save for possible bug-fixes, then, any further Backcountry Logger development will focus on hardware improvements such as different displays or batteries, and simplifications and cost-reductions of the circuitry.

Read 2 comments and join the conversation 

2 Comments so far

  1. SteveO - July 24th, 2011 8:22 am

    Great work. This logger project keeps getting smaller and more portable with each update. Keep up the good work. I look forward to more information on how I can get one of my own to tweak and use as a development platform.

  2. Christophe C. - August 9th, 2011 6:07 am

    Hey ! I just discovered your blog. Great stuff you’re doing here !
    Myself, I’m trying to find cool project I could practice on. I got my arduino uno and ladyada 2,8″ screen. Most probably I won’t be able to do the same as you (since this shield is taking nearly all the pins) but when I figure out a way to work with 2 shields, that’s definitly a project I’ll try 🙂

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