Autonomous Pepper Harvesting Robot Design
Thought for 1 min 13 sec
Stopped because the project has no available ACUs, so I can’t continue executing changes right now.
Completed so far:
- Inspected the existing schematic and found the ESP32 DevKitC, XL1509-5.0 buck regulator, 5A fuse, 12V/5V/3V3 rails, motor/sensor blocks, and existing nets already present.
- Checked datasheet guidance for:
- ESP32 DevKitC power/header pins.
- XL1509-5.0 recommended 12V-to-5V/2A application circuit.
- Existing 5A fuse rating.
- Added these Part 1 components:
- J1: 12V battery input screw terminal.
- J2: external normally-closed E-stop connector.
- D4: 10A/40V Schottky reverse-polarity protection diode.
- D5: 1N5820 XL1509 buck catch diode.
- L1: 68uH / 2A buck inductor.
- LED16: green Ready LED.
- LED17: yellow Harvesting LED.
- LED18: red Fault LED.
Not completed yet:
- The generic resistors/capacitors for LED current limiting, E-stop pull-up, buck input/output capacitors, and decoupling were attempted but not added because the generic part lookup failed.
- The newly added components are not wired yet.
- Project files for the power distribution diagram, pin table, BOM, and PCB recommendations still need to be created/updated.
- Schematic checks still need to be rerun and fixed after wiring.
Next work once ACUs are available:
- Add the missing resistors and capacitors correctly.
- Wire battery → fuse → reverse-polarity protection → 12V rail → XL1509 → 5V_SYS.
- Wire common ground, E-stop NC input, and three ESP32-driven status LEDs.
- Update documentation files and rerun checks.
Add missing passives
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Board Bring-Up Plan — Pepper Harvesting Robot Controller
Prerequisites
- Current-limited bench supply, multimeter, oscilloscope, USB cable, ESP32 programming PC.
- Start with motors and servos disconnected.
- Set A4988 current limits before connecting NEMA17 motors.
1. Visual Inspection
- Verify fuse, reverse-polarity device, electrolytic capacitor polarity, buck orientation, ESP32-CAM antenna clearance, and connector pinouts.
- Confirm no solder bridges on A4988/PCA9685 pins.
2. Power Rail Verification
Table
| Rail | Source | Expected | Current Limit First Test | Pass Criteria |
|---|---|---|---|---|
| BAT_12V_RAW | Battery/input connector | 12V nominal | 250mA no-load | No short to GND |
| 12V_MOTOR | Fuse/protection output | 12V nominal | 250mA no-load | Within input drop budget |
| 5V_SYS | XL1509-5.0 buck | 5.0V | 500mA no-load | 4.85V to 5.15V |
| 3V3_LOGIC | ESP32 DevKit regulator | 3.3V | via 5V rail | 3.2V to 3.4V |
3. Critical Signal Verification
Table
| Signal | Expected Idle | Test |
|---|---|---|
| MOTOR_ENABLE_N | HIGH disabled at reset, LOW when firmware enables | Scope GPIO27 and A4988 ENABLE |
| VERT_STEP/RING_STEP | Pulse train during motion states | Scope GPIO25/GPIO32 |
| I2C_SDA/SCL | Pulled high, 100k/400kHz traffic | Run I2C scanner |
| CAM_UART_RX/TX | 115200 baud serial | Send SCAN_TARGET command and confirm response |
| LIMIT_UPPER_N/LIMIT_LOWER_N | HIGH idle, LOW when pressed | Press each switch and read serial output |
4. Functional Validation
- Program ESP32 using the firmware starter.
- Verify LEDs: green ready, red fault, yellow harvest.
- Run I2C scan: PCA9685 at 0x40, MPU6050 at 0x68.
- Test ultrasonic distance reading with a flat target.
- Test ESP32-CAM UART response before enabling cutting motion.
- Enable one stepper at low current and command 10 steps each direction.
- Test servo motion with scissors mechanically disconnected first.
- Press E-stop while motors are enabled; A4988 outputs must disable immediately.
Pass/Fail Summary
Table
| Section | Result | Notes |
|---|---|---|
| Visual inspection | [ ] Pass | |
| Power rails | [ ] Pass | |
| Programming | [ ] Pass | |
| Sensors | [ ] Pass | |
| Motors | [ ] Pass | |
| E-stop | [ ] Pass | |
| Full harvest cycle | [ ] Pass |
Prerequisites
1. Visual Inspection
2. Power Rail Verification
3. Critical Signal Verification
4. Functional Validation
Pass/Fail Summary
