Rover Blueprint Review

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AGRO-NAV Electrical Review
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Completed
The project is now named AGRO-NAV Rover Controller and contains an 88-component, 66-net complete rover-electronics schematic. It replaces the unsafe LM7805, L298N, and IRF520 approach with protected switching-power rails, external 30 A motor-driver interfaces, fused load branches, IRLZ44N actuator outputs, I²C level shifting, E-stop gating, and transient/flyback protection.
Supporting files created:
The initial build check reported only an intentional Arduino VIN warning because the Mega is powered through 5V_LOGIC. An independent review also finished, but I could not retrieve and reconcile its final report before execution stopped.
Open items
  • Confirm each motor’s measured stall current and the actuator stall current.
  • Recalculate branch fuses, master fuse, wiring gauge, connectors, and driver ratings from those measurements.
  • The current conservative budget is approximately 40.7 A continuous and 92.8 A non-diversified peak; the 60 A master fuse is provisional.
  • Review and apply any findings from the completed independent-review thread.
  • Schematic symbols remain auto-spread rather than manually organized.
Recommended next steps
  1. Reconcile the independent-review report and correct any findings.
  2. Measure or provide the exact motor and actuator models.
  3. Perform a final schematic/ERC review.
  4. Proceed to PCB constraints and layout only after the schematic review is closed.
Execution stopped because your ACUs ran out.
Received notification from "AGRO-NAV Electrical Review" that it finished — picking the work back up.

flux

The independent electrical-review report completed, but I could not retrieve or reconcile its findings, and no additional schematic changes were made in this turn. The project remains at the previously reported 88 components and 66 nets, with motor/actuator current validation, provisional fuse sizing, final ERC review, and any review-driven corrections still open.
Execution stopped because your ACUs ran out.
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Files

Schematic

Layout

3D View

Project Specification
Project Overview
Status: Review-ready prototype schematic
AGRO-NAV is the protected electronics controller for a student autonomous agricultural rover. The schematic separates high-current 12 V loads from low-voltage compute and sensing, uses off-board high-current motor/actuator drivers, and provides named, fused interfaces for every required module and load.
Intended Use
  • Student capstone prototype operated outdoors on agricultural terrain.
  • Powered by a 12 V, 7.5 Ah sealed lead-acid battery.
  • Intended for supervised testing, not unattended production deployment.
  • Expected battery range: 10.5–14.4 V.
What the Device Should Do
  • Power a Raspberry Pi 4 and Arduino Mega 2560 from separate protected converter rails.
  • Control four geared motors as left/right parallel pairs.
  • Control a diaphragm pump, normally-closed spray solenoid, scissor-lift actuator, and MG996R soil-probe servo.
  • Read GPS, compass, IMU, ultrasonic range, humidity/temperature, and soil moisture sensors.
  • Remove motor and actuator enable immediately when the NC E-stop loop opens while preserving controller power.
Main Features
  • Master fuse and disconnect interfaces.
  • External 60 A-class ideal-diode/reverse-battery module interface.
  • SMBJ18A surge suppression on the protected battery bus.
  • Individually fused left drive, right drive, pump, actuator, low-voltage electronics, and solenoid branches.
  • Controlled star-return architecture with separately named high-current return nets.
  • Dedicated 5.1 V Pi, 5 V logic, 6 V servo, and 3.3 V sensor rails.
  • Hardware-gated safe enables using a 74HCT08.
  • Named Arduino pin map and intentional no-connect markings.
System Architecture
Text
12 V SLA
  -> external master fuse -> battery-rated master switch
  -> external ideal-diode/reverse-polarity module
  -> protected 12 V star distribution + SMBJ18A + 2200 uF
       |-> F1 left driver -> two parallel left motors
       |-> F2 right driver -> two parallel right motors
       |-> F3 pump -> MOSFET + flyback diode + local TVS
       |-> F4 actuator -> external bidirectional driver
       |-> F5 DC/DC inputs -> Pi / logic / servo / sensor rails
       |-> F6 solenoid -> MOSFET + flyback diode

Raspberry Pi 4 <-> USB data cable <-> Arduino Mega 2560
Arduino -> motor/actuator interfaces, pump, solenoid, servo, sensors
NC E-stop -> hardware AND gates -> safe driver enables
Hardware Subsystems
Battery and Protection
  • J1: SLA battery input.
  • J2: external master fuse loop; provisional 60 A slow-blow fuse and appropriately rated holder/cabling.
  • J3: external battery-rated master switch loop.
  • J4: external high-current ideal-diode/reverse-battery module, IN+/IN-/OUT+/OUT-.
  • D1: SMBJ18A TVS on VBAT_PROTECTED; 18 V standoff avoids conduction at 14.4 V charging voltage.
  • C1: 2200 uF / 25 V protected-bus bulk capacitor.
Power Distribution
  • F1/F2: provisional 20 A time-delay MINI blade fuses for left/right drive.
  • F3: provisional 10 A pump fuse.
  • F4: provisional 15 A actuator fuse.
  • F5: provisional 7.5 A electronics fuse.
  • F6: provisional 3–5 A solenoid fuse.
  • R22–R27 are logical 0-ohm star-net ties. In hardware they must be implemented as suitably rated copper, busbar, or star-terminal links—not ordinary resistor footprints.
Power Conversion
External documented modules are used rather than invented converter circuits:
  • J5: 10.5–14.4 V to regulated 5.1 V, at least 5 A continuous, dedicated to Raspberry Pi 4.
  • J6: 10.5–14.4 V to regulated 5.0 V, at least 3 A continuous for Arduino and 5 V sensors.
  • J7: 10.5–14.4 V to regulated 6.0 V, at least 3 A peak; 5 A preferred for MG996R margin.
  • J8: 5 V to regulated 3.3 V, at least 0.5 A for I2C sensors.
Compute and Control
  • A1: Arduino Mega 2560 module, directly powered from 5V_LOGIC; VIN intentionally unused.
  • RPi1: Raspberry Pi GPIO/power header representation, powered through both 5 V pins from 5V1_PI.
  • J29/J30: USB D+/D-/GND data-link representation. VBUS is intentionally disconnected to prevent back-powering; use a data-only/custom cable and verify the selected Mega USB interface operates correctly with separately powered boards.
  • J31: Pi camera/USB peripheral representation.
Drive Motors
  • J9/J10: external Cytron-class bidirectional driver interfaces.
  • Design envelope per side: 12 V nominal, 10 A continuous, 30 A short peak.
  • J11/J12 are parallel left motors; J13/J14 are parallel right motors.
  • Drivers require logic-compatible PWM/DIR/ENABLE and a documented FAULT output if used.
Pump and Solenoid
  • Q1/Q2: IRLZ44N logic-level N-channel MOSFETs with 100 ohm gate resistors and 100 kohm pulldowns.
  • IRLZ44N datasheet on-resistance is specified at 5 V and 4 V gate drive; thermal performance must still be checked using measured load current and real heatsinking.
  • D2: 10 A / 40 V SB1040 pump flyback diode.
  • D3: 3 A / 40 V 1N5822 solenoid flyback diode.
  • D4: local SMBJ18A pump transient clamp.
Linear Actuator and Safety
  • J17: external H-bridge/relay module interface with VIN, GND, PWM, DIR, ACT_EN_SAFE, FAULT, OUT_A, OUT_B.
  • J18: actuator output connector.
  • J19/J20: active-low upper/lower limit switch inputs with 10 kohm pull-ups; normally-closed switches are recommended for broken-wire detection.
  • J21: NC E-stop loop. Opening it forces ESTOP_OK low.
  • U1: 74HCT08 gates ACT_EN_CMD, LEFT_EN_CMD, and RIGHT_EN_CMD with ESTOP_OK. HCT input thresholds are compatible with 5 V Arduino logic.
Sensors
  • J22: NEO-6M GPS module on Mega Serial1. Mega TX1 is divided to about 3.33 V for GPS RX.
  • J23/J24: QMC5883L and MPU-6050 3.3 V I2C module interfaces.
  • Q3/Q4: BSS138 open-drain I2C level shifting.
  • R7/R8: exactly one shared pair of 4.7 kohm pull-ups to 3.3 V; R5/R6 are the required 5 V-side pull-ups.
  • J25: HC-SR04 on 5 V Mega GPIO; Echo is safe because it returns only to the 5 V Mega.
  • J26: DHT11 with external 10 kohm data pull-up.
  • J27: capacitive soil sensor to A0 through 1 kohm/100 nF filtering.
  • J28: MG996R on separate 6 V rail with common star-referenced ground.
Interfaces and Connections

Table

ConnectorFunction
J1SLA battery
J2/J3/J4Master fuse, switch, reverse-polarity module
J5/J6/J7/J8Pi, logic, servo, and 3.3 V converter modules
J9/J10Left/right motor driver modules
J11–J14Four geared motors
J15/J16Pump and spray solenoid
J17/J18Actuator driver and actuator
J19/J20/J21Limit switches and E-stop
J22–J28GPS, I2C sensors, ultrasonic, DHT11, soil sensor, servo
J29/J30Pi-to-Mega USB data link
J31Pi camera/USB peripheral representation
Power and Runtime Expectations
  • Battery nominal energy: approximately 90 Wh before high-rate SLA derating.
  • Heavy-load field runtime is likely roughly 15–30 minutes depending on terrain, motor current, pump duty cycle, actuator use, and battery condition.
  • A 7.5 Ah SLA is unlikely to sustain all theoretical branch peaks simultaneously without significant voltage sag.
Power Tree and Power Budget
Assumptions use conservative design envelopes where exact motor and actuator data are unavailable.

Table

LoadContinuous assumptionShort peak assumption
Left drive pair10 A @ 12 V30 A
Right drive pair10 A @ 12 V30 A
Pump8 A @ 12 V10 A startup allowance
Actuator8 A @ 12 V15 A stall allowance
Solenoid2 A @ 12 V2 A
Pi rail reflected to 10.5 V, 90% efficiency~1.6 A for 3 A output~2.7 A for 5 A output
5 V logic reflected to 10.5 V, 90% efficiency~0.4 A~1.1 A for 2 A output
6 V servo reflected to 10.5 V, 88% efficiency~0.65 A~1.95 A for 3 A output
Branch-summed total~40.7 A~92.8 A theoretical non-diversified peak
The theoretical peak is not a recommended operating point. Motor stall events must be brief and should not coincide with actuator stall and pump startup. The provisional 60 A master fuse relies on load diversity and must be validated by measurement.
Manufacturing and Assembly Expectations
  • Prototype wiring must use automotive-grade wire, crimped terminals, strain relief, and fuse holders rated for the actual current.
  • 2.54 mm headers in the schematic are logical module interfaces only and must not carry high-current battery/motor paths in the physical build.
  • High-current connectors, busbars, MOSFET heatsinks, diode mounting, and enclosure airflow remain mechanical design tasks.
Firmware-Relevant Hardware Requirements
  • Outputs default low before enable assertion.
  • Firmware may assert drive/actuator commands only when ESTOP_OK is high and both actuator limits are valid.
  • Serial1 is reserved for GPS; USB Serial is reserved for Raspberry Pi communication/debug.
  • I2C devices share the 3.3 V side of the level shifter.
Physical Design Expectations
  • Keep battery distribution and inductive load wiring away from I2C and analog sensor wiring.
  • Join returns only at the protected distribution star point.
  • Place bulk capacitors and TVS devices physically close to their connectors/loads.
  • Use sealed connectors where exposed to moisture and soil.
Important Design Decisions
  • No L298N, LM7805, IRF520, or invented high-power converter IC circuits are used.
  • High-current bidirectional drivers and DC/DC converters are off-board documented modules.
  • Hardware E-stop gates enables but does not remove controller power.
  • Raspberry Pi and Arduino communicate over USB, not GPIO UART.
Assumptions
  • Exact geared-motor stall current is unknown.
  • Actuator nominal/stall current is provisionally 8 A/15 A.
  • NEO-6M is a 5 V-powered breakout with 3.3 V UART signaling.
  • QMC5883L and MPU-6050 breakouts are treated as 3.3 V-only interfaces.
  • External motor/actuator driver FAULT outputs are open-drain or otherwise compatible with 5 V pull-ups; confirm before purchase.
Change Notes
  • Initial complete schematic created with 88 components and 66 named nets.
  • Added protected power tree, controllers, sensors, drivers, inductive-load protection, E-stop gating, and intentional no-connects.

  • Project Overview

  • Intended Use

  • What the Device Should Do

  • Main Features

  • System Architecture

  • Hardware Subsystems

  • Battery and Protection

  • Power Distribution

  • Power Conversion

  • Compute and Control

  • Drive Motors

  • Pump and Solenoid

  • Linear Actuator and Safety

  • Sensors

  • Interfaces and Connections

  • Power and Runtime Expectations

  • Power Tree and Power Budget

  • Manufacturing and Assembly Expectations

  • Firmware-Relevant Hardware Requirements

  • Physical Design Expectations

  • Important Design Decisions

  • Assumptions

  • Change Notes