I wanted to create module based on ESP8266 to manage led-strips. Since I have both RGB(WS2811) and white LEDs I wanted to create universal PCB to be able to use both kinds of strips.

Here is schematic:


I did some tests on breadboard with ESP-02, DC-DC converter and RGB, but since I didn't have anything else I couldn't test how switches are working, how mosfet is handling white strip and if resistors are placed correctly.

All missing parts are ordered now, but since it is few weeks of waiting I thought I could order PCB as well. Because this design wasn't tested I wanted to ask you for review and some suggestions before I send it to OSH Park.

https://hackaday.io/project/5646-5-wifi-rgb-enabled-led-dimmer-w-esp8266 was an inspiration for me.

EDIT: schematic updated after suggestions from Olin

  • \$\begingroup\$ You should probably put some caps on the input and output of the regulator, and it wouldn't hurt to include one or more for the module also. Otherwise I don't see any problems, but this is only a schematic design, not a PCB design. Did you mean to include the layout also? \$\endgroup\$
    – AngeloQ
    Commented Mar 7, 2017 at 22:29
  • \$\begingroup\$ @AngeloQ Sorry, I meant PCB schematic. Topic is updated. Thanks for suggestions. Are caps necessary? What values are you suggesting? I'd like to keep board as small as possible ... \$\endgroup\$
    – a_z
    Commented Mar 7, 2017 at 22:37
  • \$\begingroup\$ Depends on the regulator. It's not specified on the drawing. Some regulators are fine without caps, but some will be unstable. You should check the datasheet for recommendations. They will usually specify if they are required on either side and minimum values if so. \$\endgroup\$
    – AngeloQ
    Commented Mar 7, 2017 at 22:39
  • \$\begingroup\$ Yes, you are right. I forgot to point it out. Regulator is mini360 \$\endgroup\$
    – a_z
    Commented Mar 7, 2017 at 22:41
  • 2
    \$\begingroup\$ I'm voting to close this question as off-topic because EE.SE isn't a review service. Please keep questions problem centric and specific. \$\endgroup\$
    – Voltage Spike
    Commented Mar 7, 2017 at 23:51

1 Answer 1

  1. I'm not a fan of your component naming scheme. Naming resistors things like "RESET" and "PWM" is confusing. There is a reason a convention has evolved. Not using a common convention is annoying to those who are used to reading schematics and who you are asking a favor from. Beginners don't get to make their own rules.
  2. There is nothing indicating what the ESP-07 part is. It seems to be some microcontroller from context, but the part value should be shown on the schematic, and the part named IC1 or something.
  3. The logical flow thru the 5 V regulator is drawn backwards. Apparently 12 V is coming in from a wall wart jack, and the regulator is producing 5 V. The 12 V should be coming in from the left, and the 5 V coming out of the right side of the regulator.
  4. Both the part name and value are missing from the regulator. The name should be something like "IC2", for example.
  5. Is the regulator really a isolated DC-DC converter, as suggested by the separate OUT- and IN- pins? That would work, and perhaps it's what you had in the junk box. For a volume design, that's real waste since you aren't using the isolation. A buck converter would be significantly cheaper.
  6. Shouldn't there be ceramic caps immediately on the input and output of the regulator? If it's a isolated DC-DC power module, then maybe they are built in and you don't need them, but that's not clear from the schematic.
  7. There is no bypass cap across power and ground at ESP-07.
  8. What's the point of pulling down the GPIO2 pin externally? It's not used anywhere. If it really is GPIO, then you should be able to set it to output to keep it from floating. If it is input-only, then it is mis-labeled in the part.
  9. It's not clear why you need the 0 Ω jumper across the FET. Since the firmware controlls the FET, it has the option to turn it on whenever it wants, including all the time.
  10. You might want a weak pulldown on the GPIO13 line to keep the FET from glitching on during powerup.
  11. 10 kΩ is excessive for driving the gate of the FET. The resistor name implies this line has a PWM signal on it, so you want fast edges. I don't see the point to the resistor at all. If you need a resistor in series with whatever gets connected to the middle output pad, then put it between the FET gate and the pad, not between the micro and the gate.
  • \$\begingroup\$ 7. I've read that 0,1 uF cap should be enough (not 100% sure tho). I've placed it on schematic. 8. GPIO2 must be high to enter flash or normal boot. 9. I'm not sure if I will be able to open FET and manage led strip via data pin at the same time. I need to investigate that - for now I will just connect GPIO12 to gate and GPIO13 to LED data port. However, I'm not sure if drain and source connection are made properly - should drain be connected to LED GND, not 12V pin? This is what I've found in project that I was taking inspiration from. 10. R5 is placed. Will 10k value be ok? \$\endgroup\$
    – a_z
    Commented Mar 8, 2017 at 23:53
  • \$\begingroup\$ @a_z: Your new schematic looks much better. Give it a try. \$\endgroup\$ Commented Mar 9, 2017 at 11:48

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