flatpanel/docs/BUILD_NOTES.md

ESP32 FlatPanel — Build Notes

Bill of Materials

#	Item	Qty	Notes
1	Arduino Nano ESP32	1	ESP32-S3 based, USB-C
2	MG995 servo	1	Cover open/close (D9)
3	SG90 micro servo	1	Spare / future use
4	28BYJ-48 stepper	1	Spare / future use
5	IRLZ44N N-ch MOSFET	2	Logic-level; one for LED, one for dew heater
6	100 Ω resistor ¼W	2	Gate series resistors
7	10 kΩ resistor ¼W	2	Gate pull-downs
8	LM2596 buck converter module	1	12V → 5V for ESP32 + servo
9	12V DC power supply ≥ 4A	1	LED 2A + dew 0.5A + servo 1A peaks
10	White LED strip 12V (high-CRI ≥ Ra90)	1	Length to match aperture
11	Frosted acrylic sheet 3mm	1	Cut to telescope OD
12	Resistive heating tape / nichrome mat 12V	1	~24 Ω for 6W; see sizing table below
13	Stripboard / perfboard	1	For wiring the MOSFETs and resistors
14	JST-XH connectors or screw terminals	set	For detachable wiring
15	Heat shrink tubing assorted	pack	For all soldered joints
16	Kapton tape 10mm	1 roll	Securing heater element to acrylic
17	M2/M3 screws, standoffs	set	Mounting ESP32 and stripboard
18	1N4007 diode (optional)	1	Reverse polarity protection on 12V input
19	Multimeter	1	Required for LM2596 calibration

Dew heater element sizing

Resistance	Power @ 12V	Suitable for
48 Ω	3 W	Refractor up to 80mm
24 Ω	6 W	Refractor 80–150mm (recommended starting point)
16 Ω	9 W	Newtonians 150–250mm
12 Ω	12 W	Large apertures 250mm+

PWM control means the average power is P × (percent/100), so it is fine to overspec the element and run it at 30–50%.

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Tools Required

• Soldering iron + solder (60/40 or lead-free)
• Wire strippers and cutters
• Multimeter (essential for LM2596 setup)
• Hot glue gun or epoxy (for mechanical parts)
• Small Phillips screwdriver
• Isopropyl alcohol + cotton swabs (flux cleanup)
• PlatformIO CLI or IDE for firmware flashing

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Step-by-Step Build Instructions

Phase 1 — LM2596 Calibration ⚠ Do this FIRST before connecting anything else

1. Connect only the 12V PSU to the LM2596 IN+ and IN− terminals.
2. Set your multimeter to DC voltage, probes on OUT+ and OUT−.
3. Adjust the LM2596 trimmer pot (small brass screw):
   • Clockwise → voltage increases
   • Counter-clockwise → voltage decreases
4. Dial to 5.00 V ± 0.05 V.
5. Disconnect the PSU. The buck is now calibrated and safe to use with the ESP32 and servo.

Connecting the MG995 to an unregulated or high-voltage supply will burn out the servo electronics instantly.

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Phase 2 — Stripboard Layout

Recommended wire colour convention:

Colour	Rail
Red	12 V positive
Orange	5 V positive
Black	GND
Blue	PWM signal
Yellow	Servo signal
Grey	Load output (LED−, Heater−)

Lay three horizontal bus strips along the top of the board:

• 12V bus (red)
• 5V bus (orange)
• GND bus (black)

Place both MOSFETs at the bottom edge of the board, flat faces to the right, legs bent 90° and inserted vertically:

IRLZ44N  (flat face → you)
  Pin 1: Gate   ← 100Ω from ESP32 PWM, 10kΩ to GND
  Pin 2: Drain  → load negative (LED− or Heater−)
  Pin 3: Source → GND bus

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Phase 3 — MOSFET-A (LED Panel) Wiring

1. Insert MOSFET-A into the stripboard.
2. Solder a 100 Ω resistor between Gate and the pad that will connect to D3 on the ESP32.
3. Solder a 10 kΩ resistor between Gate and the GND bus.
4. Solder Source to the GND bus.
5. Run a wire from Drain to the negative lead of the LED strip (mark it grey/black).
6. Solder a wire from the positive lead of the LED strip to the 12V bus.

Test at this point: apply a 3.3V signal to D3 connection. The LED strip should illuminate. If it stays on at 0V, check the 10kΩ pull-down is correctly placed Gate→GND.

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Phase 4 — MOSFET-B (Dew Heater) Wiring

Repeat Phase 3 for MOSFET-B, using D5 instead of D3, and the heating element instead of the LED strip.

The heater element positive lead connects to the 12V bus; negative to MOSFET-B drain.

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Phase 5 — MG995 Servo Wiring

The MG995 uses a standard 3-wire connector:

Wire colour	Connection
Brown or Black	GND bus
Red	5V bus (from LM2596 — NOT 3.3V or raw 12V)
Orange or Yellow	D9 on ESP32

The MG995 draws up to 1A under load. Always power it from the regulated 5V rail. If the servo twitches or buzzes after connecting, re-check the LM2596 output voltage — it should not drop below 4.8V under servo load.

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Phase 6 — ESP32 Power and Ground

1. Run a wire from the 5V bus to VIN on the Arduino Nano ESP32.
2. Run a wire from the GND bus to GND on the ESP32.
3. Do not power the ESP32 from the 3.3V pin — that is an output, not an input.

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Phase 7 — Firmware Configuration and Flash

1. Open firmware/src/config.h and edit:

   #define WIFI_SSID       "your_network_name"
   #define WIFI_PASSWORD   "your_password"
   

2. Tune servo angles (power the servo and watch physical movement):

   #define SERVO_CLOSED  0    // panel in flat position
   #define SERVO_OPEN    90   // panel clear of telescope
   

3. For USB-only operation (no WiFi debug output on the serial line):

   #define SERIAL_DEBUG  false
   

4. Flash via PlatformIO:

   cd flatpanel
   pio run -t upload
   

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Phase 8 — First Power-On Checks (ordered sequence)

Work through this list in order. Stop if any step fails.

Step 1 — Bench test buck converter

• Measure 5V bus at LM2596 OUT+ with no loads connected.
• Must read 4.9–5.1V. Adjust if needed.

Step 2 — ESP32 power

• Connect ESP32 to 5V bus and GND bus only.
• Open a serial monitor at 9600 baud. You should see the boot message and a WiFi IP address printed.
• If nothing appears: check VIN wiring.

Step 3 — WiFi / Alpaca API verification

• Open a web browser and navigate to: http://<IP>:11111/management/v1/configureddevices
• You should see a JSON response including "DeviceType":"CoverCalibrator".

Step 4 — Servo test

• Using a serial terminal at 9600 baud, send: >O000 (open cover command)
• You should hear the servo move and receive: *O19000
• Send >C000 to close. Adjust SERVO_OPEN/SERVO_CLOSED angles and reflash if needed.

Step 5 — LED panel test

• Send: >B100 then >L000
• The LED strip should light up at ~39% brightness.
• Measure the voltage at MOSFET-A Drain — it should be near 0V when the LED is on (the load pulls it low).

Step 6 — Dew heater test

• Send: >T050 (50% power)
• Wait 30 seconds. The heater element should be noticeably warm to the touch.
• Send: >T000 to turn off.

Step 7 — Full integration test

• Launch controller/flatpanel_controller.py (pip install PyQt6 requests pyserial first).
• Connect in WiFi mode.
• Exercise all controls: cover, brightness slider, dew heater slider.
• Confirm the log shows successful commands and the status dots update.

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Phase 9 — Mechanical Assembly

1. Flat panel diffuser: cut the frosted acrylic to the outer diameter of your telescope tube. A friction fit or 3D-printed retaining ring works well.
2. LED strip: arrange in a spiral or grid on the rear of the acrylic. Secure with the adhesive backing or a thin layer of silicone.
3. Dew heater: run the heating element in a serpentine pattern across the face of the acrylic (the side facing the telescope). Secure with Kapton tape. Do not cover the diffuser surface with tape.
4. Cover hinge: mount the MG995 so it rotates the panel into and out of the optical path. A 3D-printed bracket is the cleanest approach. Set SERVO_CLOSED so the panel seats flush against the scope aperture.
5. Enclosure: mount the ESP32, stripboard, and LM2596 in a weatherproof ABS enclosure on the focuser end of the scope. Use cable glands for the 12V input, USB-C, servo lead, and LED/heater wires.

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Software Setup

Windows — ASCOM

1. Download and install ASCOM Platform 6.6+.
2. Download and install ASCOM Remote — the Alpaca bridge.
3. In ASCOM Remote setup, add a new CoverCalibrator device:
   • IP address: esp32-flatpanel.local (or the IP from the serial monitor)
   • Port: 11111
   • Device number: 0
4. In your capture software (N.I.N.A., SGPro, APT), choose ASCOM CoverCalibrator and select the ASCOM Remote device.

Linux / Raspberry Pi — INDI

# Install dependencies
sudo apt install libindi-dev libcurl4-openssl-dev nlohmann-json3-dev cmake build-essential

# Build the custom INDI driver
cd flatpanel/indi-driver
cmake -B build -DCMAKE_INSTALL_PREFIX=/usr
cmake --build build -j$(nproc)
sudo cmake --install build

# Test standalone
indiserver indi_esp32_flatpanel

In KStars / Ekos:

• Profile Editor → add Aux device: ESP32 FlatPanel
• In the driver's Connection tab: select WiFi or USB mode, enter host/port or serial port.

FlatPanel Controller App (all platforms)

pip install PyQt6 requests pyserial

# Run
python flatpanel/controller/flatpanel_controller.py

• Select WiFi or USB mode with the radio buttons.
• WiFi: enter the ESP32's hostname or IP and port 11111.
• USB: pick the COM port from the dropdown (click ⟳ to refresh).
• Click Connect.

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Troubleshooting

Symptom	Likely cause	Fix
Servo twitches/buzzes constantly	5V rail sags under load	Re-measure LM2596; verify 5V at servo connector under motion
LED stays on even at 0%	Gate pull-down missing	Solder 10kΩ Gate→GND on MOSFET-A
LED at wrong brightness or inverted	Firmware PWM inverted?	Check LED_PWM_PIN and LED_PWM_CHANNEL in config.h
No WiFi after flashing	Wrong SSID/password	Edit config.h, reflash
Alnitak >P000 gets no response	SERIAL_DEBUG true corrupts line	Set false, reflash
Cover angle wrong	SERVO_OPEN/CLOSED values wrong	Tune in config.h, reflash
Dew heater not warming	R too high, or MOSFET-B wiring issue	Measure Drain voltage with heater on; should be near 0V
Python app can't find serial port	Driver not loaded (Windows)	Install CH340 or CP210x driver for ESP32 USB
Connection refused on port 11111	ESP32 not on WiFi yet	Check serial monitor for boot messages
INDI driver build fails	Missing libindi headers	sudo apt install libindi-dev

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Revision History

Version	Date	Change
1.0	2026-05-17	Initial release: WiFi/Alpaca, servo, LED PWM
1.1	2026-05-17	Added USB/Alnitak mode, 12V dew heater, Python controller app