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I am designing a tool for a CNC Machine and it's my first attempt at PCB design, I was looking for some help in troubleshooting an issue.

I'm using an ESP32 MCU and it's connected to an ILI9341 2.8" TFT screen. The issue I am having is that anytime the ESP32 is restarted, either via flashing a new firmware or switching the power on and off, the screen often gets stuck in a white to black flashing loop. I can get the device to function normally by switching it off and on until it boots properly but I'm wondering if there is a design flaw in the circuitry that is causing this.

I have found forums where they mention the wiring and I think that the problem could be with the reset line. I know very little about electronics. I was concerned though that the capacitor I put on the PCB was too big to be "charged" by two 3.7v Lipos that have a max charge of 4.2v.

The circuit next to the battery terminals takes the 3.7v and drops it to 3.3v. It's an ht7333-A, a 100nF ceramic capacitor and a 1000uF 6.3v electrolytic capacitor.

Here is a link to the repo which includes the PCB design files and all the wiring, I've also included a picture of the wiring below.

Thanks for any help!

fritzing sketch:

ESP32 to ILI9341 Display: ESP32 GND -> ILI9341 GND
ESP32 3V3 -> ILI9341 VCC
ESP32 D27 -> ILI9341 LED
ESP32 D15 -> ILI9341 CS
ESP32 EN -> ILI9341 RESET
ESP32 D13 -> ILI9341 D/C
ESP32 D23 -> ILI9341 SDI
ESP32 D23 -> ILI9341 T_DIN
ESP32 D18 -> ILI9341 SCK
ESP32 D18 -> ILI9341 T_CLK
ESP32 D21 -> ILI9341 T_CS
ESP32 D19 -> ILI9341 T_OUT
ESP32 D2 -> Encoder A+
ESP32 D4 -> Encoder B+

fritzing sketch

PCB top (design files in github repo): PCB

Kenneth Orton
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    No decoupling caps? – Tyler Sep 17 '21 at 02:50
  • Sorry, i don't know what a decoupling cap is. I am new to the electronic world and have no formal training; I develop software for a living. I think the issue is the LED input to the ILI9341. Looks like there is an open pad that needs to be bridged on the back of the display to bypass the voltage regulator. The voltage regulator is there to allow the LED input to use 5v instead of 3.3v. – Kenneth Orton Feb 01 '22 at 05:24
  • Turns out the issue was the voltage regulator. The max output current of the HT7333A is 250mA and the ESP32 requires at least 500mA to operate it's radios. So, I replaced the HT7333A with the HT7833 regulator. – Kenneth Orton Mar 03 '22 at 03:38

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