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I built something like this but more special-purpose. It just switches a USB-A power source on/off. I wanted it to control my 5-volt fish-tank lights. I didn't

by sowbug 6y ago

I built something like this but more special-purpose. It just switches a USB-A power source on/off. I wanted it to control my 5-volt fish-tank lights. I didn't want to use a 120VAC smart switch for each light because I prefer to use a single USB hub to power them all, and a bonus feature was being able to PWM the lights so the fish aren't freaked out when the lights suddenly turn on 100% in the morning. I ordered PCBs from JLCPCB and components from LCSC. I think each one cost around $5 in parts, and I hand-assemble them as I need more around the house. https://github.com/sowbug/smart-usb-switch https://github.com/sowbug/smart-usb-switch Picture: https://raw.githubusercontent.com/sowbug/smart-usb-switch/master/completed.jpg https://raw.githubusercontent.com/sowbug/smart-usb-switch/ma...

fullstop 6y ago
I made lights using ws2812b leds and simulated sunrise, sunset, and a dim blue throughout the night. I used ws2812b leds, wemos d1, and a level translator since the d1 has 3.3v gpios but ws2812b technically requires a 5v signal.
- scns 6y ago
  That sounds awesome, can you do a write-up about it please?
  - andruby 6y ago
    For the software part, WLED [0] really does just about anything you’d want to do with those led strips. I drive the wemos d1 and led’s from a 12V battery with a 12-5V stepdown converter. I attach the 5V to the esp and the led’s. The 3.3V logic level works on the first led and is repeated at 5V to all subsequent led’s. [0] https://github.com/Aircoookie/WLED https://github.com/Aircoookie/WLED
    - fullstop 6y ago
      Apparently 3.3v doesn't always work with the strips, and newer ones are less likely to work, especially if you're working with a lot of lights.
      - andruby 6y ago
        My assumption was the each individual led chip will re-transmit the signal to the next led, which in effect will turn the 3.3v signal into a 5v signal between the 1st and subsequent leds. The power lines do sustain voltage drop over longer sections, so you'll want to add extra power every few meters.
        fullstop 6y ago
        Right, that is exactly how it works. If your signal to the first IC isn't perfect, and it isn't with a 3.3v signal, you can end up with incorrect colors or shifted patterns. As you add more LEDs you have a greater chance of one at the end not lighting up or having incorrect colors throughout the string. 0.7 * 5v == 3.5v, and 3.3 < 3.5. You're out of spec for the part and can't expect it to work reliably.
  - fullstop 6y ago
    I'll see what I can do.
- tW4r 6y ago
  I’ve been looking at something like this myself, did you use RGB, RGBW, RGBWW, RGBCCT or what to dynamically set the warmth of the light? I got really confused when I started looking into all these different types
  - fullstop 6y ago
    I used rgb but would like to try RGBW in the future because to get bright white on the current strip it consumes about 60 mA (@5v) per led. That's 20 mA for R, G, and B. I have two rows of 32 lights, so a beefy supply was needed along with a few places where VIN was fed to the strip.
konschubert 6y ago
I am sure this is something will be able to answer: I need to build a custom board for an ESP32 which should support low-power deep sleep and which should contain some additional circuitry (is that what you call it?) to drive an Eink display. Basically this[1] board, but a different shape and better low-power sleep properties. If I wanted to design this board myself, how long would it take to learn this? Are there good resources? If I were to pay somebody to do design this, what order of magnitude would the cost be in? > https://eckstein-shop.de/Waveshare-Universal-e-Paper-Raw-Panel-Driver-Board-ESP32-WiFi-Bluetooth-Wireless https://eckstein-shop.de/Waveshare-Universal-e-Paper-Raw-Pan...
- dementik 6y ago
  I have used TTGO ESP32 2.9" e-Paper. For my projects it contains all what I need. I recommend you to check that out.
- rvense 6y ago
  I just got an Inkplate 6 and it seems pretty cool: inkplate.io.
- na85 6y ago
  >If I wanted to design this board myself, how long would it take to learn this? Are there good resources? To learn it yourself, assuming no prior experience or knowledge, would take years of full-time study.
  - 05 6y ago
    We’re talking low speed data lines and run of the mill digital circuits, not 10GHz range RF amplifier design. A month is probably enough.
    - konschubert 6y ago
      Okay, so now I know it’ll take between 5 years and one month :D On the one hand, I have a bit of prior knowledge. On the other hand, I want a circuit with minimal power draw in ESP32 sleep mode and i’m afraid that does require some experience.
dTal 6y ago
>PWM the lights so the fish aren't freaked out How certain are you the fish can't see the PWM?
- sowbug 6y ago
  Haha, good point. I believe the ESP8266 default PWM frequency (via the Arduino library) is 1KHz, which is well above the ranges cited in the Wikipedia article for flicker fusion threshold across animal species. In my very limited testing, my fish didn't flee under plants as readily when the lights turned on more gently. https://en.wikipedia.org/wiki/Flicker_fusion_threshold https://en.wikipedia.org/wiki/Flicker_fusion_threshold

by sowbug 6y ago

fullstop 6y ago

I made lights using ws2812b leds and simulated sunrise, sunset, and a dim blue throughout the night. I used ws2812b leds, wemos d1, and a level translator since the d1 has 3.3v gpios but ws2812b technically requires a 5v signal.

scns 6y ago
That sounds awesome, can you do a write-up about it please?
- andruby 6y ago
  For the software part, WLED [0] really does just about anything you’d want to do with those led strips. I drive the wemos d1 and led’s from a 12V battery with a 12-5V stepdown converter. I attach the 5V to the esp and the led’s. The 3.3V logic level works on the first led and is repeated at 5V to all subsequent led’s. [0] https://github.com/Aircoookie/WLED https://github.com/Aircoookie/WLED
  - fullstop 6y ago
    Apparently 3.3v doesn't always work with the strips, and newer ones are less likely to work, especially if you're working with a lot of lights.
    - andruby 6y ago
      My assumption was the each individual led chip will re-transmit the signal to the next led, which in effect will turn the 3.3v signal into a 5v signal between the 1st and subsequent leds. The power lines do sustain voltage drop over longer sections, so you'll want to add extra power every few meters.
      - fullstop 6y ago
        Right, that is exactly how it works. If your signal to the first IC isn't perfect, and it isn't with a 3.3v signal, you can end up with incorrect colors or shifted patterns. As you add more LEDs you have a greater chance of one at the end not lighting up or having incorrect colors throughout the string. 0.7 * 5v == 3.5v, and 3.3 < 3.5. You're out of spec for the part and can't expect it to work reliably.
- fullstop 6y ago
  I'll see what I can do.
tW4r 6y ago
I’ve been looking at something like this myself, did you use RGB, RGBW, RGBWW, RGBCCT or what to dynamically set the warmth of the light? I got really confused when I started looking into all these different types
- fullstop 6y ago
  I used rgb but would like to try RGBW in the future because to get bright white on the current strip it consumes about 60 mA (@5v) per led. That's 20 mA for R, G, and B. I have two rows of 32 lights, so a beefy supply was needed along with a few places where VIN was fed to the strip.

konschubert 6y ago

I am sure this is something will be able to answer: I need to build a custom board for an ESP32 which should support low-power deep sleep and which should contain some additional circuitry (is that what you call it?) to drive an Eink display. Basically this[1] board, but a different shape and better low-power sleep properties. If I wanted to design this board myself, how long would it take to learn this? Are there good resources? If I were to pay somebody to do design this, what order of magnitude would the cost be in? > https://eckstein-shop.de/Waveshare-Universal-e-Paper-Raw-Panel-Driver-Board-ESP32-WiFi-Bluetooth-Wireless https://eckstein-shop.de/Waveshare-Universal-e-Paper-Raw-Pan...

dementik 6y ago
I have used TTGO ESP32 2.9" e-Paper. For my projects it contains all what I need. I recommend you to check that out.
rvense 6y ago
I just got an Inkplate 6 and it seems pretty cool: inkplate.io.
na85 6y ago
>If I wanted to design this board myself, how long would it take to learn this? Are there good resources? To learn it yourself, assuming no prior experience or knowledge, would take years of full-time study.
- 05 6y ago
  We’re talking low speed data lines and run of the mill digital circuits, not 10GHz range RF amplifier design. A month is probably enough.
  - konschubert 6y ago
    Okay, so now I know it’ll take between 5 years and one month :D On the one hand, I have a bit of prior knowledge. On the other hand, I want a circuit with minimal power draw in ESP32 sleep mode and i’m afraid that does require some experience.

dTal 6y ago

>PWM the lights so the fish aren't freaked out How certain are you the fish can't see the PWM?

sowbug 6y ago
Haha, good point. I believe the ESP8266 default PWM frequency (via the Arduino library) is 1KHz, which is well above the ranges cited in the Wikipedia article for flicker fusion threshold across animal species. In my very limited testing, my fish didn't flee under plants as readily when the lights turned on more gently. https://en.wikipedia.org/wiki/Flicker_fusion_threshold https://en.wikipedia.org/wiki/Flicker_fusion_threshold