u/Afraid_Loss5187

Hey everyone, having a weird issue combining modules on an ESP32.

My Setup:

Keypad: 4x4 Matrix via I2C expander on GPIO 16 (SDA) and 17 (SCL).

RFID: Two RC522 readers sharing default VSPI pins: SCK (18), MISO (19), MOSI (23).

Reader 1 Control: SDA/CS (5), RST (27).

Reader 2 Control: SDA/CS (14), RST (13).

Power: Everything (both RFIDs + I2C expander) is powered from the ESP32 3.3V pin. Esp is powered from usb.

The Problem

Individually, everything works perfectly fine. However, when combined together, the RFID readers stop working completely. Now, when I go back to test just a single RFID reader on its own, it looks like one of them isn't responding or working at all anymore.

Is this a 3.3V power/current limit issue from the ESP32 regulator, a hidden pin conflict, or am I hitting the infamous RC522 MISO line-hogging bug where the inactive reader crashes the SPI data bus? Any advice on how to fix this is appreciated!

I made a high-side switch to control 12V power to an L298N motor driver using an ESP32/Arduino GPIO pin. I want to know if my design is correct and why my MOSFETs keep getting damaged.(i tested on breadboard, one got damaged one worked. the worked one got damaged later. being careful to work quickly and let each leg cool before soldering the next one to avoid heat damage)

**Goal:**

Control 12V supply to L298N using a 3.3V or 5V GPIO pin from ESP32/Arduino.

Is this circuit design correct for switching 12V with a 3.3V/5V GPIO?

P-Channel MOSFET high-side switch circuit. Components: IRF9Z24N or F4905S P-channel MOSFET , 2N2222 NPN transistor, 10kΩ resistor.
12V supply connects to MOSFET Source. 10kΩ pullup resistor connects between MOSFET Gate and Source (12V). 2N2222 Collector connects to MOSFET Gate. 2N2222 Emitter connects to GND.
I didnt add 1kΩ resistor between GPIO input pin and 2N2222 Base. MOSFET Drain is the switched 12V output. All GNDs are common.

https://preview.redd.it/ybxdwes6i3yg1.png?width=922&format=png&auto=webp&s=3826720be5581935e051ac3a1b3ca6794684b8d5