I have been trying to make my poi easier for anyone to duplicate by eliminating the costly custom circuit board. So I tried to make it on stripboard, which was a disaster. Here is the idea:
And here is how it ends up looking on the stripboard (with tilt switch):
So that looks great and all but in practice, having to cut the stripboard and solder and everything else, there are too many possibilities for shorts and troubleshooting it was turning out to be a nightmare. There are 18 solder points on the board above, not to mention cutting the metal on the stripboard (under the esp-01)
Here is another idea, I am trying to make this simple, the D1 mini costs just $1 more and can run on 5v which is the right voltage for the LED strip anyway. This is the new circuit:
Now we have only 9 points to solder (not including the LED Strip, I didn’t include it above either).
I also re-imagined my poi outer shell, to give access to the usb programming port on the D1 Mini, so this will help with development as well.
Looking forward to putting this all together, and updating my tutorial series (if it all works as planned)
Although the Smart Poi is based on ESP-01 for size reasons, I find it easier to use the excellent D1 mini for testing. Here is the basic setup:
Notice that the D1 mini is powered from a battery source (4 x NiMH AA in series). This is not entirely necessary, you could get away with plugging in the D1 mini via USB, and connecting the APA102 strip to the 5v pin. The problem comes in when the LED strip starts drawing too much power, you will have dropouts in Wifi connectivity, or wdt resets and won’t know if it’s the code or just power.
Use the offline code from my Github repo to get started:
The ESP-01 are so cheap and versatile, you just have to use them. (Get one on Aliexpress for just $2 here: http://s.click.aliexpress.com/e/kNB84VvO) In the couple of years using these amazing cheap powerful chips, I have had my share of problems. Here are some big ones to avoid:
Problem: The programmer doesn’t work all the time.
Solution: Increase power. I use a cheap usb interface like this one:
First of all you need to know that you can’t just plug the ESP-01 module into the handy header socket and press upload on the Arduino IDE. You will get an error, as the ESP-01 needs to be put into programming mode. I did this by shorting the GPIO 0 and gnd with a wire. The ESP-01 still plugs in.
Now Arduino can upload! Unfortunately I was having intermittent “unable to upload” errors even after this hack, and a new batch of ESP’s from a different supplier barely worked at all. Something else had to be done. Adding a breadboard power supply did the trick, unfortunately with the addition of 7 wires and a breadboard, as well as an adapter for the ESP-01 and a switch to toggle programming mode…
*Update: you can ignore the above, nowadays I just click on upload and quickly unplug/re-plug the esp-01 (unplug the 8 pin header, not the usb!). Seems to do the trick!
Problem: Blink sketch says it’s uploaded but LED doesn’t blink.
Solution: After checking the pin numbering and seeing some possible related issues on a google search, I checked out the Arduino ESP8266 settings.
It turns out that all ESP-01 are not made equal. Most come with 1Mb flash but the type of flash (?) and the way it’s connected can vary. Hence the “flash mode” option. In my case, after extensive testing, DOUT was the correct choice. The LED blinks again.
Problem: After ESP8266 tool update, the dreaded WDT reset happens after a few minutes (time depends on what the program is doing)
Solution: After some testing I found it was a memory overflow causing the issue. This led me to refine the google search and finally I found a relevant bug on github, to do with LwIP (the wifi firmware?). Here is the setting in Arduino:
Changing to LwIP v1.4 Higher Bandwidth worked for me… It’s possible that this bug has been fixed by now, but I am sticking with the working version at the moment.
To summarize, ESP-01 is a bit tricky to program, there are so many variables in programming it, however they are so small and cheap – and despite many mistakes I have yet to brick one of these. I guess it’s worth the hassle*.
I also use the very capable D1 Mini for development (below).
The code is all Arduino, with FastLED library for led driving. The only issue with ESP8266 is power consumption, the wifi uses far more power than the Atmega328 for example, however compared to the LED strips (144 LED’s at once) it is negligible.