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Schematic

rev B 2026-08-03 14 sections, 1 sheet, full system. ESP32-S3-DevKitC-1-N16R8.
Wattplot v2 schematic, rev B, 2026-08-03. 14 sections: power input, 5V/3.3V regulation, ESP32-S3, USB-C + ESD, dual DRV8871 H-bridges, DS18B20, soil moisture, INA219, current-based homing, status LED, I2C expansion, title block.
Download PNG (750 KB) Download drawio Open in app.diagrams.net Wiring guide → Pin map →

The 14 sections

Read left-to-right, top-to-bottom. Power tree at the top, ESP32-S3 in the middle, drivers and sensors at the bottom. Every section card is tagged with its subsystem so you can tell at a glance which part of the controller it belongs to.

01Power input (12 V)

XT60, 10 A ATO fuse, SS34 reverse-polarity, SMBJ16A TVS, bulk cap.

Subsystem: Power tree
025 V buck (MP1584)

4.5–28 V → 5 V, 3 A peak. Feedback divider, catch diode, PWR LED.

Subsystem: Power tree
033.3 V LDO (AMS1117)

1 A. Don't add a second relay without re-budgeting.

Subsystem: Power tree
04ESP32-S3

DevKitC-1-N16R8. USB-C, RST, BOOT, antenna keep-out.

Subsystem: MCU / Controller
05USB-C + ESD

5.1 kΩ CC pull-downs, USBLC6-2SC6 ESD protection.

Subsystem: MCU / Controller
06Actuator H-bridge (DRV8871, U5a)

Drives the linear actuator that tilts the panel. 3.6 A peak, current sense via IPROPI, nFAULT output.

Subsystem: Actuator (panel tilt)
07Solenoid H-bridge (DRV8871, U5b)

Drives the irrigation / latch solenoid. Single-direction mode (IN2 tied to GND on board). nSLEEP tied high (always enabled).

Subsystem: Solenoid (water / latch)
08DS18B20 (1-Wire)

4.7 kΩ pull-up, ESD TVS, JST. 3 sensors in parallel.

Subsystem: Sensors
09Soil moisture

Capacitive, low-pass filter, ESD TVS, 3-pin JST.

Subsystem: Sensors
10Battery V sense

100k / 10k divider (×11.0), 3.3 V clamp TVS.

Subsystem: Power tree
11Current-based homing (U5a IPROPI)

Current spike via the actuator H-bridge's IPROPI pin detects endstop. Threshold: 0.80 A for ≥200 ms, HA-tunable.

Subsystem: Actuator (panel tilt)
12Status LED (PWM)

Monochromatic LEDC PWM. Brightness is the only parameter; the RGB channels in the firmware are ignored.

Subsystem: HMI / Status
13I²C expansion

4-pin header, 4.7 kΩ pull-ups. INA219 × 2, future IMU.

Subsystem: Expansion
14Title block

Project info, design summary, design rules.

Subsystem: Meta