ESP32 Cam With PCA9685

Hardware: ESP32 Cam

Author: DJ Sures

This firmware converts a ESP32 Cam into an EZB for ARC to connect to it.

This firmware turns an ESP32-CAM into a Wi-Fi EZB-compatible controller that can run Synthiam ARC peripheral control and drive up to 16 PWM/servo channels through an attached PCA9685 breakout board - while still supporting live camera streaming from the onboard OV2640.

It’s designed for robots that need vision + 16 servo outputs without upgrading to a larger controller board.

What the Firmware Provides

EZB Compatibility (Peripheral Controller) The ESP32 accepts ARC control commands and behaves like an EZB-compatible controller for common robotics tasks such as:

servo position commands
PWM output control
digital on/off ports
UART expansion passthrough (Serial2)

ARC can connect and send commands exactly like it would to an EZB style controller.

Integrated Camera Streaming The firmware initializes the ESP32 camera driver and streams JPEG frames to ARC over a dedicated TCP connection. This provides live video feedback in ARC while the controller side remains responsive.
PCA9685 Expansion for 16 Channels Instead of using ESP32 GPIO for servo timing, this firmware uses an Adafruit PCA9685 PWM servo Driver over I2C. That means:

ARC ports D0 to D15 map directly to PCA channels 0 to 15
servo timing stays stable even while Wi-Fi and camera streaming are active
you get more usable servo outputs than most ESP32-CAM boards can provide natively

Simultaneous Operation Camera streaming and EZB command handling run side-by-side. The ESP32 can:

stream video continuously
accept and execute servo/digital/PWM commands
keep TCP connections alive for both ARC control + camera streaming

Required Hardware

To use the expanded servo/digital output capability, you’ll need:

an ESP32 camera module supported by the firmware
a PCA9685 board (commonly the Adafruit-compatible 16-channel PWM driver)

The PCA9685’s servo power rail is not intended to be powered by the ESP32-CAM. Use a dedicated servo supply and share ground.

Supported ESP32 Camera Boards

This firmware includes camera model pin maps for many ESP32 camera variants, including:

CAMERA_MODEL_AI_THINKER
CAMERA_MODEL_WROVER_KIT
CAMERA_MODEL_ESP_EYE
CAMERA_MODEL_M5STACK_PSRAM
CAMERA_MODEL_M5STACK_V2_PSRAM
CAMERA_MODEL_M5STACK_WIDE
CAMERA_MODEL_M5STACK_ESP32CAM
CAMERA_MODEL_M5STACK_UNITCAM
CAMERA_MODEL_M5STACK_CAMS3_UNIT
CAMERA_MODEL_TTGO_T_JOURNAL
CAMERA_MODEL_XIAO_ESP32S3
CAMERA_MODEL_ESP32_CAM_BOARD
CAMERA_MODEL_ESP32S3_CAM_LCD
CAMERA_MODEL_ESP32S2_CAM_BOARD
CAMERA_MODEL_ESP32S3_EYE
CAMERA_MODEL_DFRobot_FireBeetle2_ESP32S3
CAMERA_MODEL_DFRobot_Romeo_ESP32S3

Only enable one camera model at a time. A mismatched model typically causes camera init failures or empty frames.

How ARC Port Mapping Works in This Firmware

This firmware’s "mapping" is intentionally simple and consistent:

PCA Channels

ARC ports D0 to D15 map to PCA9685 channels 0 to 15
these channels can be treated as:
- servos (position 0 - 180)
- PWM percent (0 - 100)
- digital on/off (full off / full on)
digital ports are write only. The read option will simply read the cached value of the last state. This is a limitation of the PCA9685.

Because PCA9685 is external hardware, you don’t need to fight ESP32-CAM GPIO limitations to get stable outputs.

ADC Inputs

ADC reads are currently stubbed (returns 0) in the shown firmware due to the PCA9685 not having ADC input pins. It is a write-only PWM module.

Network Behavior

The firmware runs two TCP servers:

Port 23: EZB compatible command/control channel
Port 24: camera JPEG streaming channel

It also supports two Wi-Fi modes:

Access Point Mode (default in the sample)

ESP32 creates its own Wi-Fi AP (ex: GetOffMyLawn)
default IP is 192.168.1.1
easiest for direct robot setup with no router required

Client Mode

ESP32 connects to an existing Wi-Fi network
the device IP is shown in Serial output
useful for robots on a larger LAN

Camera Compression Auto-Management

The ESP32-CAM has limited buffer space for image payloads. This firmware includes optional dynamic JPEG compression tuning:

checks frame sizes over a window of frames
adjusts JPEG quality to keep frames within a target range
reduces stalls and helps keep streaming smooth

This is especially useful when lighting changes cause frame size spikes.

Benefits of This Firmware

More servo Outputs PCA9685 provides 16 stable PWM/servo channels without relying on ESP32 PWM timers.

Stable Timing While Streaming Servo timing is offloaded to PCA hardware, so video streaming doesn’t wreck servo pulses.

All-in-One Robot Board You get camera, control, and servo expansion in one compact setup.

Simple ARC Port Model ARC sees consistent channels (0-15) that don’t change per the ESP32-CAM board layout.

Great Fit for Servo-Heavy Robots Robotic heads, arms, animatronics, pan/tilt rigs, hexapods, and any build where ESP32 pins alone aren’t enough.

Typical Use Cases

Perfect for robotics projects that need both vision and many outputs:

humanoid heads with multiple facial servos
pan/tilt + arm systems
animatronic creatures
camera rovers with extra actuators
inspection bots with a camera + servo tools

Summary

This firmware converts an ESP32 camera module into a Synthiam ARC compatible EZB style controller with:

live OV2640 camera streaming over TCP
EZB compatible control channel for ARC commands
16-channel PCA9685 servo/PWM expansion
AP or Client Wi-Fi operation
optional auto JPEG compression adjustment for stable streaming

To deploy successfully:

Select the correct CAMERA_MODEL_* define
Set your Wi-Fi mode (AP or Client)
Wire the PCA9685 to the configured SDA/SCL pins and confirm the address
Flash the firmware and connect from ARC (camera + controller)

Firmware Versions

Download

1) What You Need

Hardware

ESP32 camera board (one of the supported CAMERA_MODEL_* boards)
PCA9685 16-channel PWM/Servo driver board (Adafruit-compatible)
Jumper wires
Servo power supply (recommended: 5-6V, adequate current for your servos)
Common ground between servo power, PCA9685, and ESP32

Software

Arduino IDE (or compatible build environment) (Set serial monitor to 115,200)
Board package: ESP32 by Espressif Systems v3.3.5
Library: Adafruit PWM servo Driver Library v3.0.2
This firmware sketch ZIP package

2) Choose the Correct Camera Model

In the firmware, locate the camera model section and uncomment exactly one line:

// #define CAMERA_MODEL_AI_THINKER
// #define CAMERA_MODEL_WROVER_KIT
// ...

Important

Only one model should be enabled.
A wrong model usually causes an error in the serial monitor

3) Configure Wi-Fi Mode

Access Point Mode (default)

AP mode creates a Wi-Fi network hosted by the ESP32.

#define AP_MODE
#define WIFI_AP_SSID "GetOffMyLawn"
#define WIFI_AP_PWD  ""

ESP32 AP IP is typically 192.168.1.1
You connect your PC to this SSID, then ARC connects to the ESP32’s IP.

Client Mode

Client mode joins your existing Wi-Fi network.

// #define AP_MODE  // comment out AP_MODE
#define WIFI_CLIENT_SSID "My Network"
#define WIFI_CLIENT_PWD  "My Password"

Serial Monitor prints the assigned IP address once connected.

4) Wire the PCA9685 to the ESP32-CAM

The firmware uses these defines:

#define PCA_SDA_PORT 14
#define PCA_SCL_PORT 15
#define PCA9685_ADDR 0x40

Typical wiring

ESP32 GPIO 14 PCA9685 SDA
ESP32 GPIO 15 PCA9685 SCL
ESP32 GND PCA9685 GND
PCA9685 VCC 3.3V (logic power) or 5V depending on your PCA board design
- Most PCA9685 boards accept 3.3V logic fine.
Servo power:
- Use the PCA9685 servo power input (often labeled V+) with a separate 5-6V supply
- Share ground: servo supply GND must connect to ESP32 GND / PCA GND.

PCA9685 address

Default is 0x40. If you changed address jumpers (A0-A5), update:

#define PCA9685_ADDR 0x40

5) Check for Pin Conflicts (Camera vs I2C)

ESP32-CAM boards often consume many GPIO pins for the camera bus. The serial monitor will present an error if there is a conflict. If your chosen PCA_SDA_PORT or PCA_SCL_PORT conflicts with a camera pin, the firmware will print an error repeatedly and halt.

If this happens:

Change PCA_SDA_PORT / PCA_SCL_PORT to pins that exist on your board and are not used by the camera.

6) Compile & Upload

Arduino IDE settings (typical)

Board: select the correct ESP32 board profile for your module (AI Thinker ESP32-CAM / ESP32 Wrover / ESP32-S3 etc.)
Flash Frequency: default/auto is fine
Partition scheme: default is usually fine unless you add extra features
Serial monitor: 115200

Upload the firmware, then open Serial Monitor.

7) Verify Startup in Serial Monitor

On boot, you should see messages similar to:

camera initialized successfully
Wi-Fi mode started (AP or client)
server started and waiting for client
PCA9685 initialized (if your firmware includes the probe / init logs)

If the PCA9685 is missing/wrong address/miswired, the firmware may:

print an error forever (if you enabled the I2C probe + fatal loop)
or appear to run but servo outputs won’t work

8) Connect From Synthiam ARC

This firmware presents two network services:

EZB/Controller Server: TCP port 23
Camera Streaming Server: TCP port 24

A) Connect as a Controller (EZB style)

In ARC:

Add a connection to the ESP32’s IP address
Use Port 23
Connect

You should see the firmware accept the client and print:

"Client ezb connected from "

B) Connect the Camera Device

In ARC:

Add the Camera Device / camera streaming connection (whatever your ARC workflow is for this ESP32-CAM stream)
Use the same ESP32 IP
Use Port 24
Start the camera device

You should see:

"Client cam connected from "

9) Understanding ARC Port Mapping (PCA9685)

This firmware treats PCA9685 channels as ARC ports:

ARC Port 0 PCA Channel 0
ARC Port 1 PCA Channel 1
ARC Port 15 PCA Channel 15

Servo behavior

ARC servo position commands map to PCA servo pulses
A position of 0 is treated as "release/detach" (turn off PWM on that channel)

Digital behavior

Digital on/off uses PCA "full on" / "full off" behavior.

10) Common Troubleshooting

Camera won’t initialize

Symptoms:

esp_camera_init() error printed

Fix:
Ensure you selected the correct CAMERA_MODEL_*
Reseat camera ribbon cable

Try lowering:

//#define XCLOCK_FREQUENCY 20000000
#define XCLOCK_FREQUENCY 10000000

PCA9685 not detected / servos don’t move

Check:

SDA/SCL wiring
Address (0x40 unless changed)
PCA power and shared ground
Servo power supply is connected and sufficient current

AP mode connects but ARC can’t reach it

Check:

Your PC is connected to the ESP32 SSID (not your home Wi-Fi)
Use IP 192.168.1.1 (typical AP config in this firmware)

Client mode keeps rebooting

This firmware restarts if Wi-Fi drops in client mode:

if (WiFi.status() != WL_CONNECTED)
  ESP.restart();

If your Wi-Fi is unstable, consider AP mode for testing.

11) Recommended First Test

Flash firmware
Open Serial Monitor @115200
Confirm camera init success
Confirm Wi-Fi starts and prints IP
Connect ARC controller to port 23
Connect ARC camera stream to port 24
Send a servo command to port 0 and confirm motion

12) Safety Notes

Don’t power servos from the ESP32 board.
Always share ground between ESP32, PCA9685, and servo power.
Start with conservative servo endpoints (SERVO_MIN_US / SERVO_MAX_US) and adjust only if needed.

Supported Capabilities

Can stream video v4 codec
The controller supports the streaming Video v4 codec on a TCP or UART or USB connection.
Hardware UART TX/RX with DMA buffer and adjustable baud rate
Contains 1 or more hardware UARTs with TX/RX functionality and DMA RX buffering.
Native WiFi Connectivity from ARC
Controller supports WiFi connectivity using TCP between your computer with ARC.
PWM Duty on digital ports
Digital ports can output a PWM between 0% and 100%.
PWM servos on digital ports
The controller supports PWM Servos on digital ports. These are also called Hobby servos.
PWM servos on digital ports can release their position
PWM servo driver on digital ports support the feature to release their holding position.
Read/Write Digital I/O Ports
The ports marked as being digital will respond to Read and Write commands of boolean logic. The status of the digital port will be either TRUE or FALSE when voltage is detected or not, respectively.

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