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ESP8266 & Analog Strips - Power Problem
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ESP8266 & Analog Strips - Power Problem

by andypoms on Sat Sep 23, 2017 8:54 am

I'm tying to use a HUZZAH ESP8266 Breakout to control some 60 LED/m RGB Analog Strips (3m right now, but that will get a little shorter when I mount it) & have a strange problem...

The circuit I'm using is detailed in the Adafruit RGB LED Strips tutorial (using N-Channel MOSFETs, paying special attention to the part that says "For longer strips requiring more than 1 Amp, wire the power directly to the strip, then run power and ground wires back to the Arduino.", except I can't send 12V back to the ESP8266 (it would burn out the chip). All the grounds (chip, MOSFETs, both the 6V & 12V supplies) are all connected together to form a single ground for the entire circuit.

When connected to a computer for code upload & power the circuit works without an issue (with independent 12V DC for the LEDs .
ESP8266_LedStrip-Works.jpg
ESP8266_LedStrip-Works.jpg (145.47 KiB) Viewed 168 times


When I try to power the circuit with two power supplies (not connected to the computer), it doesn't work...
ESP8266_LedStrip-Fails.jpg
ESP8266_LedStrip-Fails.jpg (146.31 KiB) Viewed 168 times


Now I know just enough about electronics to be dangerous - and I'm thinking I created a ground loop here & that's my problem (but I'm not sure).

What's a better way to power this? I thought about a voltage divider, but that's not for significant loads... (Is the ~250mA the ESP8266 draws considered significant?) Ideally, one power supply for both the chip & the LEDs would be great.

andypoms
 
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Re: ESP8266 & Analog Strips - Power Problem

by adafruit_support_bill on Sat Sep 23, 2017 9:02 am

Do you have a ground connection between your MOSFET control circuit and your processor?

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Re: ESP8266 & Analog Strips - Power Problem

by andypoms on Sat Sep 23, 2017 9:27 am

adafruit_support_bill wrote:Do you have a ground connection between your MOSFET control circuit and your processor?

Yes, All the grounds are connected into one big ground bus (all the black wires) & I've hit them all with a multimeter & have connection between all of them.

ESP8266_LedStrip-Ground.jpg
ESP8266_LedStrip-Ground.jpg (158.08 KiB) Viewed 159 times

andypoms
 
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Re: ESP8266 & Analog Strips - Power Problem

by adafruit_support_bill on Sat Sep 23, 2017 9:44 am

Is there anything in the code that depends on serial communication via the FTDI? You might want to add a couple lines of code to blink the on-board LED to verify that the code is running.

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Re: ESP8266 & Analog Strips - Power Problem

by andypoms on Sat Sep 23, 2017 10:53 am

adafruit_support_bill wrote:Is there anything in the code that depends on serial communication via the FTDI? You might want to add a couple lines of code to blink the on-board LED to verify that the code is running.

There is one "Serial.begin(115200)" and a few lines with "Serial.println()" & "Serial.print()" for debugging. I have other ESP8266's with similar code that do not have this issue when powered directly, so that shouldn't be an issue.

I added some basic Blink Code to my sketch.
  • Tested with just the FTDI powering the chip - Onboard LED Blinks. Good.
  • Tested with the FTDI powering the chip and the 12V powering the LEDs - Onboard LED Blinks, LED strip works. Good.
  • Tested with just the 6V power supply powering the chip & nothing else - I get two different results. Don't know why, the only thing that is changing is plugging and unplugging the 6V supply
    • Onboard LED Blinks. Good.
    • Onboard LED does NOT blink & there is a buzz from the chip. Fail.
  • Tested with the 6V for the chip & the 12V for the LED strips - Onboard LED Blinks, LED strips do NOT. Fail.
    • This was tested when the 6V only was successful

I didn't hear the buzz before, but it's only there when the LED is not blinking.

andypoms
 
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Re: ESP8266 & Analog Strips - Power Problem

by adafruit_support_bill on Sat Sep 23, 2017 11:13 am

Write some code to turn the RED channel on 100%. Then measure the voltage between GND and the gate on the RED channel MOSFET. Do this with the ESP8266 powered both ways.

Regarding the buzz. I have not heard of that symptom before. Is this repeatable?

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Re: ESP8266 & Analog Strips - Power Problem

by andypoms on Wed Nov 08, 2017 4:19 pm

Sorry for the delay on this (the real world got in the way of my tinkering)...

adafruit_support_bill wrote:Write some code to turn the RED channel on 100%. Then measure the voltage between GND and the gate on the RED channel MOSFET. Do this with the ESP8266 powered both ways.
Same ~3V reading on both power options.

adafruit_support_bill wrote:Regarding the buzz. I have not heard of that symptom before. Is this repeatable?
I think the 6V power supply I was using was unstable & the ESP8266 was being overpowered.

I've reworked the entire circuit so it run from the 12V power supply - using a 5V 1.5A Linear Voltage Regulator - 7805 TO-220 to power the ESP8266.

Bill, thanks for your help on digging into this.

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Re: ESP8266 & Analog Strips - Power Problem

by adafruit_support_bill on Wed Nov 08, 2017 5:25 pm

Thanks for the follow-up!

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