I will do basic IOT project with esp-wroom-32. but I am machanical student. I need to help please check my design.

my component: - esp-wroom-32 - button - pad-resistor - locig level converter - ft232rt ( but i don't found library) - pins I am sory for my english. enter image description here

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  • \$\begingroup\$ Add some bulk/decoupling capacitance at the usb input \$\endgroup\$ – Linkyyy Apr 9 '19 at 22:41

I am not sure about the actual circuit, but generally, I prefer using a ground plane in all of my projects. To do that in EAGLE, while in the schematic window draw a polygon object (square) on top your design then assign its signal to "GND". Like this:

enter image description here

Also, make the USB connector closer to the side of the PCB.

  • 2
    \$\begingroup\$ Probably worth mentioning that the OP would have to remove the GND plane near the ESP32s antenna. \$\endgroup\$ – Wesley Lee Apr 10 '19 at 0:01
  • \$\begingroup\$ why ? it is insulator. \$\endgroup\$ – Yunus Emre Biçinci Apr 10 '19 at 7:43
  • \$\begingroup\$ Adoobll i know polygon object but i used single layer. thank you. \$\endgroup\$ – Yunus Emre Biçinci Apr 10 '19 at 7:46
  • 1
    \$\begingroup\$ @YunusEmreBiçinci Large conducting surfaces block wireless signals, and having one right under the antenna could also affect how the antenna behaves at the the intended frequency. Documentation for wireless modules with trace antennas usually specifies an area around the antenna where conductor should be minimized. For the WROOM-32, page 2: espressif.com/sites/default/files/documentation/… \$\endgroup\$ – MBer Apr 10 '19 at 17:49

Looks good, here are some recommendations:

  1. Ditto on the decoupling capacitor on the USB 3.3v and GND
  2. You may have some issues with the GPIO pin going straight to GND when the button is pressed. I would throw in a resistor.
  3. Depending on the amperage you are using for the LED, you may need a transistor for power. The MAX is 12ma per pin on the ESP32, and usually LEDs use closer to 20ma.
  4. There is no trace running to the central GND pad on the center of the ESP32.
  5. The ESP32 MUST be powered with 3.3V, so unless you are using a usb power source that regulates at 3.3v, it will fry your ESP. Most USB sources are 5V.

Explain 1: Take a look at this or this to learn more about decoupling. There are plenty of posts about decoupling capacitors and why they are needed. Basically, you don't want your device to produce a electric signal that interferes with other devices. Decoupling signals that may have changing signal rates unintentionally is one way to fight this.

Explain 2: You will need an actual resistor, just using a bare wire is not recommended. Through hole resistors are VERY cheap.

Explain 5: You can get a fixed voltage 5v to 3.3v regulator that solves this problem. Here is an example of one.

Note: This post has been updated to answer your questions.

  • \$\begingroup\$ firstly thank you so much for your recommendations. but I don't understood your fırst, for second, ı will use wire for resistor.third, you are right, I overlooked but Will the resistance reduce current ?thank you again ı will look all recommendation. \$\endgroup\$ – Yunus Emre Biçinci Apr 10 '19 at 7:42
  • \$\begingroup\$ Resistance reduces the overall power allowed through the wire. Do a google search for "resistor needed for led" and you will find many calculators that do a better job of explaining this than I can explain here. \$\endgroup\$ – PyFire Apr 10 '19 at 12:30

It has already been mentioned that additional decoupling capacitors are needed. Have a look at the datasheets of the ESP32 module and the FTDI chip for more specific information:

The second datasheet in particular leads to the question: How do you plan to power the ESP32 module, FTDI chip and level shifter?

And is the 5V pin of the connector used to feed or source 5V?

If I'm not mistaken, your schematic has a major problem here:

  • If you want to power it via USB, then you need a voltage regulator to reduce the USB voltage from 5V to 3.3V.
  • If you want to power it directly, e.g. via the 5V pin of the connector, then you again need a voltage regulator. The level shifter won't do that.

If I'm not mistaken, the FTDI chip needs to be either powered from the USB port, or you need to feed it 5V (and not 3.3V as in the current schematic).

  • \$\begingroup\$ Okey sory my mistake. I use power with USB. Some line not connect because I use one layer and I use wire. \$\endgroup\$ – Yunus Emre Biçinci Apr 10 '19 at 11:02
  • \$\begingroup\$ Your schematic does not show the USB connection. Are you using some module with the FTDI chip? If so, what's the specification of the VCC pin? Is it feeding or sourcing voltage? Is it 3.3 or 5V? \$\endgroup\$ – Codo Apr 10 '19 at 12:45
  • \$\begingroup\$ I am sorry for tell you about power voltage. ftdi available pins 3.3v and 5v. I edit schematic. I will updates. \$\endgroup\$ – Yunus Emre Biçinci Apr 10 '19 at 13:14
  • \$\begingroup\$ The FTDI chip does not provide 3.3V. You need to take 5V directly from the USB port and feed it both to a voltage regulator and your 5V output pins. The voltage regulator will require two more capacitors. \$\endgroup\$ – Codo Apr 10 '19 at 13:27
  • \$\begingroup\$ İ use ft232rl. this ftdi convert 5V to 3.3v. I use 3.3v for esp32 and i using 5V for the sensor. \$\endgroup\$ – Yunus Emre Biçinci Apr 10 '19 at 13:51

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