ESP32 Forum

I am developing a simple alarm for my greenhouse based on an ESP32-DEVKITC-V4. The dev board has an ESP32-WROVER-IE. The alarm will be triggered by HomeAssistant and I am using ESPHome to develop the code. So far I have breadboarded my experimental circuits which all work properly when I have it connected to my computer via a USB cable. The alarm has a 12 VDC buzzer and I am using a 12VDC power supply. I have connected a GPIO port to a 2N2222A bipolar junction transistor base (simply because I have several) with a series 4.7K resistor, and the power supply (+) to the buzzer, the buzzer gnd to the emitter and the collector to the breadboard gnd. That all works well. The last step is to replace the USB cable with a DC power regulator to convert the 12 VDC supply to 3.3 V for the ESP32. The regulator is a Mean Well N7803-1CW (datasheet: https://mm.digikey.com/Volume0/opasdata ... Series.pdf. I connected the regulator red lead to the breadboard (+) rail (which is connected to the power supply (+)), the regulator black lead to the breadboard (-) rail (which is connected to the power supply (-)), and the regulator yellow (output) to the dev board 3.3v input (pin 37, labelled VDD3P3_CPU, labelled 3V3 on the dev board). I did not have the USB cable connected. The red power indicator LED flashed continuously between bright then dim even though I wasn't downloading any code. It took several minutes until HA recognized that this device was available. HA recognized the ESP32 instantly with the USB power connection. Also, I don't think that it worked.

What does the flashing dev board LED mean? Any ideas about what I did wrong?

TIA!

According to the ESP32-DEVKITC-V4 documentation, the onboard LED means that 5V is being applied to the module on pin 19. Is that not the case?

If the LED is fluctuating in intensity, that doesn't sound good. Did you say that HA is still recognizing the ESP32 so it seems to be functioning at least somewhat?

Do you have a schematic or wiring diagram for your setup?

I do have a schematic but I need to update it. I will post soon. However, nothing is connected to pin 19 and I don't have any 5v on the board (that I know of). The LED is on when either 5v is applied or USB is connected. But in this case the LED isn't 'on', it is flashing. I haven't been able to find what that means. I think that HA did eventually recognize that the ESP32 was available, which suggests that it also recognized the switches (I was testing both 5v (powered from a GPIO) and 12v (powered from the 12v power supply) LEDs and buzzers, so 4 HA switches). I could try disconnecting the LED and buzzer from the straight GPIO connections which is the intended implementation. I want to have only the 12v power supply and a power regulator for simplicity. The buzzer is much louder at 12v than 5v (as expected).

Here is my schematic. I am new to this (electronic design and building these projects) so please be kind. The schematic is accurate. I have measured the power supply output and it is just over 12 VDC. I measured the power converter and it is 3.3 - 3.4 VDC. The pin that I connected the converter to on the dev board is labeled '3V3' on the board and identified as the 3.3 V power supply in the espressif devkitc doc. I tested last night after removing the LED and buzzer that were directly connected to GPIOs. The board red LED still alternates between bright and normal. HA does not recognize the device as being available.

I am using KiCad 9 to draw my schematic. I can export it to the clipboard but can't figure out how to paste it here. Would someone kindly tell me how?