# Darlingtonia Zeer Pot — Wiring Guide ## ESP32-C3 SuperMini Pinout (as used in this project) ``` USB-C ┌─────────┐ │ ESP32 │ │ C3 │ │ SuperMini│ 5V ◄──┤5V D8 ├── (unused) GND ◄──┤GND D10├── (unused) 3V3 ──►┤3V3 D7├── (unused) (unused) ───┤D6 D4├──► GPIO4 → OneWire bus (DS18B20×2) (unused) ───┤D1 D3├──► GPIO3 → MOSFET gate (pump) (unused) ───┤D0 D2├──► GPIO2 → Moisture sensor ADC │ D5├──► GPIO5 → Float switch └─────────┘ ``` **Pin assignments in firmware (`darlingtonia-zeer-pot.ino`):** | GPIO | Function | Direction | Notes | |------|--------------------|-----------|--------------------------------| | 4 | DS18B20 OneWire | I/O | Shared bus, 4.7kΩ pull-up to 3V3 | | 3 | Pump MOSFET gate | OUTPUT | HIGH = pump ON, 10kΩ pull-down | | 5 | NC float switch | INPUT | HIGH = water OK, 10kΩ pull-up | | 2 | Moisture sensor | ADC INPUT | 12-bit, capacitive probe | ## Power Chain ``` ┌──────────────┐ ┌──────────────────┐ ┌──────────┐ │ 5W Solar │ USB │ TP4056 │ B+/B-│ 18650 │ │ Panel ├─────►│ USB-C Charger ├─────►│ 3.7V │ │ (5V USB-C) │ │ (w/ protection) │ │ ~3Ah │ └──────────────┘ └───┬──────────┬───┘ └──────────┘ OUT+ │ │ OUT- ▼ ▼ ┌─ VBAT rail ──────── GND rail ─┐ │ (3.0–4.2 V) │ │ │ │ C1: 10µF (bulk decoupling) │ │ │ ├──► ESP32 5V pin │ │ (onboard regulator → 3V3) │ │ │ │ C2: 100nF across 3V3/GND │ │ │ └──► MT3608 VIN+ (boosts to 12V) │ MT3608 VOUT+ ──► Pump (+) │ (via MOSFET low-side) │ │ ``` **Key point:** The ESP32-C3 SuperMini has an onboard voltage regulator. Feed raw VBAT (3.0–4.2V) into the **5V pin** — the board regulates down to 3.3V internally. The 3V3 pin is an **output** that powers the sensors. ## Wiring — Step by Step ### 1. Power rails on breadboard Use a half-size breadboard (30 columns). Dedicate: - **Top power rail (+):** VBAT (red wire from TP4056 OUT+) - **Top power rail (−):** GND (black wire from TP4056 OUT−) - **Bottom power rail (+):** 3V3 (orange wire from ESP32 3V3 pin) - **Bottom power rail (−):** GND (bridge to top GND rail) ### 2. ESP32-C3 SuperMini placement Straddle the ESP32-C3 across the center channel of the breadboard. Orient it with USB-C pointing outward for easy programming access. Connect: - **5V pin → VBAT rail** (red jumper) - **GND pin → GND rail** (black jumper) - **3V3 pin → 3V3 rail** (orange jumper) ### 3. DS18B20 temperature probes (×2, shared OneWire bus) Both probes connect to the same GPIO4 bus. Each probe cable has 3 wires: | Wire color (typical) | Function | Connect to | |----------------------|----------|------------------| | Red | VDD | 3V3 rail | | Black | GND | GND rail | | Yellow (or white) | DQ (data)| GPIO4 bus wire | **Critical:** Add a **4.7 kΩ pull-up resistor (R2)** between the DQ bus wire and the 3V3 rail. Without this, OneWire communication will fail. ``` 3V3 ──┬── DS18B20 #1 VDD ── DS18B20 #2 VDD │ [R2 4.7kΩ] │ GPIO4 ┼── DS18B20 #1 DQ ─── DS18B20 #2 DQ │ GND ──┴── DS18B20 #1 GND ── DS18B20 #2 GND ``` ### 4. MOSFET pump driver (IRLZ44N, low-side switch) The R385 12V pump is switched by an N-channel MOSFET on the **low side** (between pump negative terminal and GND). The MT3608 boosts VBAT to 12V for the pump. ``` VBAT ──► MT3608 VIN+ MT3608 VOUT+ (12V) ──► Pump (+) Pump (−) ──► MOSFET Drain MOSFET Source ──► GND GPIO3 ──┬──────────► MOSFET Gate │ [R4 10kΩ] (pull-down: keeps pump OFF when ESP sleeps/resets) │ GND ``` **IRLZ44N pinout (face toward you, legs down):** ``` ┌───┐ │ │ G D S (1) (2) (3) ``` - Pin 1 (Gate): GPIO3 + R4 pull-down - Pin 2 (Drain): Pump (−) terminal - Pin 3 (Source): GND rail **Flyback diode (SS14 / 1N5819):** Place across the pump terminals to protect the MOSFET from inductive voltage spikes when the pump turns off. - **Cathode** (band side) → Pump (+) / 12V side - **Anode** → Pump (−) / MOSFET drain side ### 5. Float switch (NC, side-mount) The float switch is a normally-closed (NC) contact mounted in the reservoir. When the float is up (water present), the switch opens → GPIO5 = HIGH → pump OK. When the float drops (low water), the switch closes → GPIO5 = LOW → pump blocked. ``` 3V3 │ [R3 10kΩ] (pull-up) │ GPIO5 ──────┤ NC Float Switch ├──── GND ``` - Float up (water OK): switch open, GPIO5 = HIGH (pulled to 3V3 through R3) - Float down (low water): switch closed, GPIO5 = LOW (pulled to GND through switch) ### 6. Capacitive moisture sensor 3-wire analog sensor. **Must be 3.3V-compatible** (not 5V-only). | Sensor wire | Connect to | |-------------|------------| | VCC | 3V3 rail | | GND | GND rail | | A (analog) | GPIO2 | No pull-up/pull-down needed — the sensor outputs a DC voltage proportional to moisture level. The ESP32 reads it with 12-bit ADC. ## Complete Bill of Materials (discrete components on breadboard) | Ref | Value | Purpose | |-----|---------|--------------------------------------| | R2 | 4.7 kΩ | OneWire pull-up (DS18B20 bus) | | R3 | 10 kΩ | Float switch pull-up to 3V3 | | R4 | 10 kΩ | MOSFET gate pull-down to GND | | C1 | 10 µF | Bulk decoupling across VBAT/GND | | C2 | 100 nF | High-freq decoupling across 3V3/GND | | D1 | SS14 | Flyback protection across pump | | Q1 | IRLZ44N | N-MOSFET, low-side pump switch | ## Quick-Start Checklist 1. [ ] Solder header pins on ESP32-C3 SuperMini (if not pre-soldered) 2. [ ] Place ESP32 on breadboard, connect 5V/GND/3V3 to rails 3. [ ] Flash firmware via USB-C (`platformio run --target upload`) 4. [ ] Wire R2 (4.7k) + one DS18B20 probe to GPIO4 — verify temp reading via serial 5. [ ] Add second DS18B20 to same bus — verify both sensors auto-identify 6. [ ] Wire MOSFET + R4 (10k pull-down) + pump + flyback diode 7. [ ] Test pump: `digitalWrite(3, HIGH)` in serial monitor 8. [ ] Wire float switch + R3 (10k pull-up) to GPIO5 9. [ ] Wire moisture sensor to GPIO2, verify ADC readings 10. [ ] Connect TP4056 + 18650 battery, disconnect USB 11. [ ] Verify system wakes from deep sleep, reads sensors, reports MQTT 12. [ ] Connect solar panel to TP4056 USB input, deploy outdoors ## Schematic See `schematic-sections.pdf` (6-page CircuiTikZ/LaTeX schematic).