Photo voltaic Powered Conways Sport of Life
I made an e-ink based mostly, photo voltaic powered model of the well-known Conways Game of Life.
Usually these celular automations run at no matter pace our eyes discover to be visually pleasing however I wished to see what a model that mirrored the true worlds power patterns could be like.
In my model the world and its mobile inhabitants should survive low energy peroids every night time together with lowered energy peroids when its wet or snowy. In addition they can solely reproduce with any regularity within the brightest components of a summers day reflecting our personal worlds patterns.
The system hangs on a wall a number of toes from the window. Round 9am on vivid summer time days I’ll see the primary new technology being born for the day. By that point the small drawdown from the extremely low energy core of the esp32 could have been replenished by the photo voltaic panel and the battery voltage could have recovered to three.3v.
Every time that occurs the ULP will get up the primary core to calculate the subsequent technology based mostly on the earlier one which is saved in RTC reminiscence. Then it’s going to activate the show driver board and push the subsequent set of pixels to be drawn earlier than scripting this new technology to reminiscence and coming into deep sleep once more.
On vivid days I’ll see nearly a thousand such refreshes however on a wet day I would see much less then ten and if we now have a wet week I may not see any in any respect. So long as battery voltage can keep above the esp32’s minimal 2.6v the ULP will maintain ready and watching and the cells will dwell on, ready for one more likelihood to breed when the circumstances enhance. In fact in the event that they don’t all the world will die (at ~2.6v) and I’ll should manually restart my universe.
Improvement
I began this mission a pair years in the past and because the first portion of the mission concerned mosty coding it went very effectively. Utilizing a dev board I had the unit working off of battery in a number of days and I used to be fairly glad. I then wanted a board with an environment friendly LDO in order that I might get the ability utilization of the esp32’s ULP down to close the marketed 10µA. At this level I made a decision to take the leap away from devboards and get my fingers soiled with a naked module.
That is the place issues slowed down. When the boards got here I noticed that that they had castellated edges which regarded inconceivable to solder to. Additionally I couldn’t get the boards to flash b/c I hadn’t used flexy pins earlier than and I didn’t push the board in all the best way. My enthusiams for the mission deminished and it obtained shelved for over a 12 months.
Fortunately the hackaday podcast began speaking about how soldering to castellated edges was doable by hand and that gave me the push I wanted to dive again in.
I obtained the board flashing the primary night time and after some follow was capable of get wires soldered by hand to the castellated edges on the subsequent.
I discovered that the ESP couldn’t monitor voltages excessive sufficient (~3v in my testing) to present me working vary (above 3.3v for display screen updates and three.3-2.6v for deep sleep) so I added a low draw voltage divider based mostly on the uPesy ESP32.
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I discovered that utilizing a 40f supercap for power storage didn’t reliabily get the system by means of the night time but in addition that the BMS from the vape pen lithium batteries would shut down when the display screen refreshed at low voltages because of the present draw voltage dip. After enjoying round with capicitors I finally settled on an unprotected lithum battery from one other vape pen. This does imply that I might hurt the battery drawing it all the way down to 2.5v however I haven’t seen it go that low in precise utilization and I discover vape pens discarded on the road with sufficient regularity that I’m not too involved.
After all of the kinks have been labored out I lastly noticed my anticipated power utilization patterns and had a working system.
Software program
This aspect of issues is fairly easy and I lastly had a purpose to write down the usual Life impelentation. I take advantage of a bitset to compactly retailer the cell state since booleans every take up a byte on this artecture, which even at my pretty low cell counts is simply too massive to suit into RTC reminiscence.
I used the ESP-IDF for the primary time as a result of the Arduino UPC help even now appears fairly experimental (though I’ve used it up to now efficiently) and it was a optimistic experence.
The ULP assembler code is generally based mostly off the instance given within the ESP-IDF besides it solely seems to be for a higher voltage restrict.
I additionally used the CalEPD libary to drive the e-ink show.
Code could be present in my Github.
Armegedons
In CGoL with low cell counts you possibly can often run into looping conditions. Usually you’d verify for these by conserving round some variety of earlier states and evaluating them however I don’t have the reminiscence to try this between deep sleeps so I simply begin from a random setting state each 100 body which additionally retains the show fairly full and fascinating.
Its not fairly behind the scenes however I am nonetheless proud my naked wires soldered to the castellated edges labored.