Board Description — P2 Lamp
Overview
P2 Lamp is a compact LED controller board built around an ESP32-C6-DEVKITC-1-N8 development board. Its job is to accept a higher-voltage input supply, generate the regulated rails required by the controller, provide a robust data output for an external LED load, and expose a simple control interface for user inputs.
At a system level, the board has four main jobs:
- Accept external DC power through a screw terminal.
- Convert input power to 5 V using a buck regulator.
- Convert 5 V to 3.3 V for the controller and input logic.
- Read user controls and drive LED data output.
The design is arranged as a practical controller module rather than a bare MCU design. Instead of using a raw ESP32 module, it uses an ESP32-C6 DevKitC board footprint, which simplifies firmware bring-up, programming, and replacement.
Functional Architecture
1. Power Input Block
Main purpose: bring external power safely onto the board.
Main components:
- J7 — 2-position screw terminal, main input connector
Logic behind it:
- The board is expected to be powered from an external DC source.
- A screw terminal is used because it is simple, robust, and appropriate for bench wiring or installation wiring.
- This input feeds the switching regulator stage that generates the rest of the board supplies.
2. 5 V Buck Regulator Block
Main purpose: efficiently create a 5 V rail from the input voltage.
Main components:
- U1 — LM2596S-5.0/NOPB buck regulator
- L1 — 68 uH output inductor
- D1 — 1N5822 Schottky diode
- C1 — 100 uF input bulk capacitor
- C2 — 100 uF output bulk capacitor
- TP1 — 5 V test point
Logic behind it:
- The input supply is higher than the logic rails, so a buck converter is used first to reduce dissipation.
- The LM2596 is a classic non-synchronous step-down regulator. It needs:
- an input capacitor to stabilize the source,
- a Schottky freewheel diode,
- an inductor for energy transfer,
- and an output capacitor to smooth the switched waveform into DC.
- This block generates the board’s 5 V rail, which is also made available at a test point for debugging and measurement.
- Using a switching regulator here is the right choice because dropping a high input voltage down to 5 V with only a linear regulator would waste too much power as heat.
3. 3.3 V Logic Supply Block
Main purpose: create the 3.3 V rail used by the ESP32 and control logic.
Main components:
- U2 — AMS1117-3.3 linear regulator
- C3 — 10 uF input capacitor
- C4 — 10 uF output capacitor
- C5 — 100 nF output bypass capacitor
Logic behind it:
- The ESP32 DevKit and control signals require 3.3 V.
- The design first generates 5 V, then drops that to 3.3 V with an AMS1117-3.3.
- This gives a simple and familiar logic rail generation stage.
- The AMS1117 requires both input and output capacitors for stability, and a small 100 nF bypass capacitor is added to improve high-frequency decoupling.
- This rail powers the ESP32 board and the external control connector.
4. Controller / Processing Block
Main purpose: execute firmware logic, read controls, and produce LED control output.
Main components:
- U3 — ESP32-C6-DEVKITC-1-N8
- R2 — 10 kOhm pull-up on EN / CHIP_PU
- C6 — 100 nF local decoupling on 3.3 V
- C7 — 10 uF local bulk decoupling on 3.3 V
Logic behind it:
- The board uses an ESP32-C6 DevKitC rather than a bare module to reduce risk and speed up prototyping.
- This choice gives:
- built-in programming support,
- easier replacement,
- fewer RF layout concerns than a raw module implementation,
- and a more beginner-friendly hardware platform.
- The EN line is pulled up with R2 so the controller stays enabled in normal operation.
- C6 and C7 provide local supply decoupling near the controller power input.
- The ESP32 handles the application logic in firmware, including reading controls and generating the LED data stream.
Signals currently used on the DevKit:
- CHIP_PU / EN — controller enable/reset line
- UART_TXD / GPIO16 — LED data output source
- GPIO2 — fader input
- GPIO10 — button 1 input
- GPIO11 — button 2 input
- GPIO4 — button 3 input
- ESP_3V3 and multiple GND pins — power
Unused pins are intentionally left unconnected.
External Interface Blocks
5. LED Data Output Block
Main purpose: provide a WS2815-compatible outgoing data signal for the external LED load.
Main components:
- J5 — 2-pin JST-XH LED data connector
- U4 — 74AHCT1G125SE-7 single-gate 5 V logic buffer
- R3 — 33 Ohm series resistor on LED data
- C10 — 100 nF decoupling capacitor for U4
Connector intent:
- Pin 1: GND
- Pin 2: LED data output
Logic behind it:
- The external LED connection is separated onto its own connector to keep wiring simple.
- The board now uses a 5 V AHCT buffer so the ESP32’s 3.3 V output is translated into a stronger 5 V logic-level data signal.
- This makes the output stage much better suited for WS2815-style LED inputs, which are not reliably driven by a bare 3.3 V MCU output.
- R3 = 33 Ohm provides source termination to reduce ringing without excessively slowing the waveform.
- The earlier shunt capacitor on the data line was removed because it was inappropriate for the LED protocol edge speed.
- C10 is placed locally across the 5 V supply for the output buffer so the translated signal stays clean.
- The data path is:
- ESP32 GPIO16 / UART_TXD -> U4 -> R3 -> J5 pin 2
Important system note:
- J5 carries data and ground only.
- An external WS2815 matrix must still be powered from its own 12 V supply, with shared ground back to this controller board.
6. Control Input Block
Main purpose: allow external user controls to connect to the ESP32.
Main components:
- J6 — 6-pin JST-XH control connector
- R4 — 10 kOhm pull-up for GPIO10 button input
- R5 — 10 kOhm pull-up for GPIO11 button input
- R6 — 10 kOhm pull-up for GPIO4 button input
- C9 — 100 nF filter capacitor on GPIO2 fader input
Connector intent:
- Pin 1: 3V3
- Pin 2: GND
- Pin 3: Fader input (GPIO2)
- Pin 4: Button 1 input (GPIO10)
- Pin 5: Button 2 input (GPIO11)
- Pin 6: Button 3 input (GPIO4)
Logic behind it:
- This connector groups all user controls into one place.
- The board now supports three discrete button inputs plus one fader / analog-style input.
- Button inputs use pull-up resistors so the firmware can treat them as active-low switches to ground.
- The fader input is treated as an analog-style control input, and C9 helps filter noise on that signal.
- Providing both 3.3 V and GND on the control connector makes it easy to attach passive controls such as potentiometers and momentary switches.
7. Power Indicator Block
Main purpose: show that the 3.3 V rail is alive.
Main components:
- LED1 — indicator LED
- R1 — 330 Ohm current limiting resistor
Logic behind it:
- A simple power LED is connected to the 3.3 V rail through a current-limiting resistor.
- This gives immediate visual confirmation that the logic rail is present.
- It is useful during assembly, bring-up, and debugging.
Supply Rails and Net Intent
VIN
Raw input power from the screw terminal. This is the upstream supply for the buck converter.
5V
Generated by the LM2596 buck regulator. Used as the intermediate rail and as the supply for the WS2815 output buffer.
3V3
Generated by the AMS1117 and used for the ESP32 and external controls.
GND
Common return path for all power and signals.
EN
Controller enable/reset net.
GPIO16 / LED_DATA_OUT path
Buffered firmware-controlled output path for the external LED signal.
GPIO2 / GPIO10 / GPIO11 / GPIO4
User control input signals for the fader and three buttons.
Why the Design Is Structured This Way
Two-stage regulation
The power path is intentionally split into:
- input -> 5 V switching regulator
- 5 V -> 3.3 V linear regulator
This keeps the large voltage drop efficient while still giving a simple, clean logic rail for the controller.
Dev board instead of raw module
Using the ESP32-C6 DevKitC reduces implementation risk and keeps development fast. It avoids needing a custom USB/programming circuit and simplifies firmware bring-up.
Separate connectors by function
The connectors are split into:
- power input,
- LED output,
- control input
This makes the wiring easier to understand and reduces integration mistakes.
Properly conditioned LED output
The LED output is no longer just a raw MCU pin. It now includes:
- logic-level translation to 5 V,
- local decoupling on the buffer,
- and light source termination at the output.
That makes the interface much more suitable for an external WS2815-style LED matrix.
Simple, robust user inputs
The control connector is designed around easy external wiring:
- three active-low buttons,
- one filtered fader input,
- shared 3.3 V and ground on the same connector.
This is straightforward for harnessing and easy to support in firmware.
Board Layout Summary
- Board size: 80 mm x 65 mm
- Corner radius: 3 mm
- Stackup: standard 2-layer board
- Placement style: top-side assembly only
Layout intent:
- Power conversion parts are grouped together.
- The ESP32 is central to the control section.
- The control connector is placed near the controller-side GPIO support parts.
- The LED connector is grouped with the output buffer and series resistor.
- The board corners are rounded for a cleaner enclosure-friendly outline.
Current Design Status
- The control block has been updated to support three buttons plus one fader input.
- The LED output block has been updated for a WS2815-style external interface using a 74AHCT1G125 buffer.
- The affected PCB areas were rerouted after these updates.
- The project is currently in a clean checked state with no open ERC/DRC issues.
Notes and Caveats
- Some passives started as generic parts and were later assigned manufacturer metadata for manufacturing checks.
- A few generic package/property combinations may still deserve a future cleanup pass if the design is being prepared for production rather than prototyping.
- The current design is best understood as a prototype-ready controller board with clean routing and resolved review checks, not yet a fully production-optimized BOM.
In Plain Terms
This board is a small power-and-control hub for LED lighting:
- it takes in DC power,
- makes the voltages the electronics need,
- runs an ESP32 controller,
- reads a fader and three buttons,
- and sends a buffered data signal out to an LED load.
The design choices favor clarity, serviceability, and easy bring-up over extreme miniaturization.