Project Start Planning

Thought for 3 sec

The schematic executor reports completion, but I cannot inspect or independently verify its output because no ACUs are currently available. Remaining work is to review ERC, confirm all 18 servo connectors and both 5 V domains, validate the HC-SR04 divider/PCA9685 wiring, then proceed to PCB placement and routing.

kkarthikeya

Check ERC for unconnected pins, power conflicts, and other schematic errors.

Thought for 2 sec

flux

I can’t run or inspect ERC because the account currently has no available ACUs. No ERC verification was completed in this session.

Remaining checks:

Unconnected and dangling pins
Power-output conflicts and incorrect power-net types
All 18 servo connector signal/power/ground connections
PCA9685 address, OE, I²C, VDD, V+ and decoupling
HC-SR04 ECHO divider and ESP32 GPIO connections
Separation of +5V_SERVO and +5V_ESP32, with common GND

kkarthikeya

Re-run ERC for unconnected pins, power conflicts, and any other schematic errors.

Thought for 2 sec

flux

I still can’t re-run ERC because the account has no available ACUs. No new schematic checks or changes were made.

Once ACUs are available, the remaining task is to run ERC and inspect unconnected pins, power conflicts, all 18 servo ports, both PCA9685s, the HC-SR04 divider, and separation of +5V_SERVO from +5V_ESP32.

Check ERC later

Inspect power nets

Review unconnected pins

Check servo interfaces

Files

Schematic

Layout

Preview

Firmware Getting Started

Pin Mapping

Table

Function	ESP32 pin	Connected hardware
I2C SDA	GPIO21	U2/U3 SDA, R3 pull-up
I2C SCL	GPIO22	U2/U3 SCL, R4 pull-up
Ultrasonic TRIG	GPIO17	J23 TRIG
Ultrasonic ECHO	GPIO16	R1/R2 divided ECHO
PWM driver A	I2C 0x40	J5-J20, channels 0-15
PWM driver B	I2C 0x41	J21-J22, channels 0-1

Arduino Dependencies

ESP32 Arduino board support package.
Wire library.
A PCA9685 driver such as Adafruit PWM Servo Driver Library.

Minimal Initialization

Cpp
#include <Wire.h>
#include <Adafruit_PWMServoDriver.h>

Adafruit_PWMServoDriver pwmA(0x40);
Adafruit_PWMServoDriver pwmB(0x41);

constexpr int PIN_TRIG = 17;
constexpr int PIN_ECHO = 16;

void setup() {
  pinMode(PIN_TRIG, OUTPUT);
  digitalWrite(PIN_TRIG, LOW);
  pinMode(PIN_ECHO, INPUT);

  Wire.begin(21, 22);
  pwmA.begin();
  pwmB.begin();
  pwmA.setPWMFreq(50);
  pwmB.setPWMFreq(50);
}

Servo Channel Mapping

Leg 1: U2 channels 0, 1, 2.
Leg 2: U2 channels 3, 4, 5.
Leg 3: U2 channels 6, 7, 8.
Leg 4: U2 channels 9, 10, 11.
Leg 5: U2 channels 12, 13, 14.
Leg 6: U2 channel 15; U3 channels 0, 1.

HC-SR04 Measurement Example

Cpp
long readEchoUs() {
  digitalWrite(PIN_TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);
  return pulseIn(PIN_ECHO, HIGH, 30000);
}

Startup Sequence

Start serial diagnostics.
Configure TRIG/ECHO GPIO.
Start I2C on GPIO21/22.
Initialize PCA9685 devices at 0x40 and 0x41.
Set all servo outputs to safe neutral/disabled values before enabling gait control.
Verify ultrasonic timeout behavior before entering the motion loop.

Pin Mapping
Arduino Dependencies
Minimal Initialization
Servo Channel Mapping
HC-SR04 Measurement Example
Startup Sequence