ESP32 PCB Design Assistance

davi74

davi74

I need a PCB where the center is an ESP32. There's 2 motors connected via CAN (3.3v, tx, rx, ground, on 2.54mm spacing female), an external servo driver board, which needs ground, tx, rx (all female header pins). The battery connects to a 14.8 power bus on the PCB. From this 14.8 power bus, we connect to a small buck converter (3.3V, power and ground from PCB 14.8V) (external, not on PCB), which in then powers the ESP 32. The 14.8 power bus also powers another external, not on the pcb, buck converter which returns back 12.2 V to a new power bus, which just needs to receive up to 20amps via female. From this power bus, we power the servo driver as well ( via 2 male headers, gnd and 12.2v, on the PCB)

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Power Budget
Architecture
  • Battery input: 14.8 V nominal on 14V8 bus via J4.
  • External buck converter #1: takes 14V8 from J5 and returns 3V3 on J5 for ESP32 and logic headers.
  • External buck converter #2: takes 14V8 from J6 and returns 12V2 on J6 for high-current 12.2 V bus J7 and servo power header J8.

3.3 V rail loads

LoadTypicalPeak / design allowanceNotes
ESP32-WROOM-32E~240 mA500 mAWiFi TX peaks; external buck should be rated at least 1 A for margin.
Motor logic headers J1/J2 3.3 V pinsunknownuser-definedIf external motor boards draw logic power from this PCB, include them in the 3.3 V buck rating.
Recommended 3.3 V buck output rating: >=1 A, more if motor interface electronics are powered from J1/J2.

12.2 V rail loads

LoadTypicalPeak / design allowanceNotes
12.2 V bus J7unknownup to 20 AUser requirement.
Servo driver power J8limited by headerup to 3 A connector ratingDo not exceed the installed 2.54 mm male header rating.
Recommended 12.2 V buck output rating: 20 A minimum if the full J7 bus current is required. At 12.2 V and 20 A, output power is 244 W.
Reflected 14.8 V current
Assuming 90% buck efficiency for the 12.2 V converter:
I_14V8 = (12.2 V * 20 A) / (14.8 V * 0.90) = 18.3 A
The 14.8 V bus should therefore be designed for at least 20–25 A if the 12.2 V rail may deliver 20 A. The 3.3 V ESP32 buck adds only about 0.25 A at 14.8 V for a 1 A / 3.3 V output at 90% efficiency.
Design decisions / warnings
  • I used terminal-block style connectors for high-current buses because 2.54 mm headers are not safe for 20 A.
  • The motor links are wired as 3.3 V logic TX/RX because the requested pinout was 3.3V, TX, RX, GND. True CAN requires CANH/CANL and a CAN transceiver, not direct TX/RX wiring.
  • J8 is a 2.54 mm male header rated around 3 A; it should only feed low-current servo-driver control/power input, not the full 20 A bus.

    Architecture

    3.3 V rail loads

    12.2 V rail loads

    Reflected 14.8 V current

    Design decisions / warnings

Documents

    Power Budget

    Firmware Starter — ESP32-WROOM-32E

Assets

Assets are files uploaded to this project which can be used in various ways.

ESP32 Power Bus Controller thumbnail
ESP32-centered controller PCB with 14.8 V battery bus, external 3.3 V and 12.2 V buck converter interfaces, motor logic headers, and servo driver connections.

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor

Qty 1

HQonline

$1.69

LCSC

$1.56

TME

$0.00

Controls