John Floren

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Posted 2024/2/25

Monocle programming, battery life, brightness

I’ve continued to play with the Brilliant Monocle over the last few days.

First off, I wrote the rough framework of a Go library for interfacing with it, because I don’t like using Python and I sure don’t want to use Visual Studio.

Using that framework, I put together some simple demos. One just displays the current time, updated every second. The other tests battery life.

Battery Life

I’ve been very curious as to how long the battery will last during regular use. Official word has been that it should last an hour to two hours in “normal use”. I wrote a little thing (cmd/batterytest in the repo linked above) to verify this.

Basically, it pushes over some code to the Monocle which blanks the screen and then every minute outputs (over Bluetooth) the current time and the battery state. On the host system side, we try to send a single carriage return every 10 seconds to make sure the Monocle is still on. Once that send fails, we assume the device is dead and output the elapsed time.

I did two runs yesterday:

That’s roughly 1.6-1.8% depletion per minute, or basically exactly the 1 hour battery life they claimed from full.

I also made some rough estimates of how long it takes to charge. It took 11 minutes to go from 0% to 52%, and then 16 minutes to go from 52% to 76%. This matches expectations: rechargeable batteries charge fast at first, then slow down the closer they get to full.

If it takes almost 30 minutes to get to 76% (which based on my depletion rates above is good for about 45 minutes of operation), you can expect to spend almost as much time charging it as you do using it.

This afternoon, I had to run an errand. At about 13:55, I took my Monocle out of its case, quickly loaded the clock demo, and left the house wearing it. I got back home at almost exactly 15:00, and as I stepped out of the pickup the Monocle turned off. Again, this shows a runtime of about 1 hour in light use (draw some text on the screen, sleep 1 second, draw text again; no Bluetooth used at all).

Screen Brightness & Wearability

I’ve previously been pretty pessimistic about the brightness on a sunny day; before I had the device, I believed it would not do well in bright light, and when I first attempted to check for myself I declared it almost unusably dim.

After wearing it for an hour today, driving and walking around on a more or less clear afternoon, I’d say it’s better than my first assessment. My first test was out in front of my home, which happens to be particularly bright due to light reflecting off the light-painted townhouses. In more normal conditions, the text on the screen is dim but generally readable. I was using yellow text (display.YELLOW) at brightness level 4 (max).

I was hesitant to wear the device while driving at first, but a few minutes alleviated the concern. It doesn’t block vision in any important way (the opaque portions are well above anywhere you’d need to look while driving). Given that it was just displaying a clock, I did not find it distracting; indeed, the text is mostly invisible unless you choose to look at it. At a stoplight, I could quickly glance down and note the current time. I think it would be suitable for navigation prompts, assuming your trip is less than an hour long.