John Deere Tractor Navigation System - Electronics

This repository contains the PCB layout for a shield-style board designed to interface with the NUCLEO-H745ZI-Q development board. The PCB integrates various components and connection interfaces required for the tractor navigation system developed in collaboration with John Deere, serving as a practical application of embedded systems concepts. The implementation details of this electronics design can be found in the embedded software repository.

System Overview

The custom PCB serves as a connection hub for the system's components, handling:

• Power distribution to components
• CAN interface (FDCAN1) for encoder data
• I2C connection (I2C4) for the MPU6050 IMU
• SPI interface (SPI5) for the nRF24L01 wireless module
• PWM signal routing (TIM13, TIM14, TIM1) for motors and buzzer

Power Distribution

The PCB design includes three power input screw terminals. Here's our implementation from the embedded repository:

Logic Power Screw Terminals

• 5V terminal: Connected to external LM2596 regulator outputting 5V
• 3.3V terminal: Connected to external LM2596 regulator outputting 3.3V
• Both regulators were powered by 7.4V from two 3.7V Li-Po cells in series

STM32 Power Screw Terminal

• 7.4V terminal: Connects directly to NUCLEO-H745ZI-Q's VIN
• Board configuration: JP2 jumper on pins 3-4
• Power specifications:
  • Input range: 7-11V
  • Current draw varies with voltage:
  • 800mA @ 7V
  • 450mA @ 7-9V
  • 250mA @ 9-11V

ESC and STM32 Connection

• The ESC is a separate pre-built circuit with its own power connections and is not powered through the PCB.
• In our setup, we used a 7.4V Li-Po 2S battery to power both:
  • The ESC directly
  • The STM32 through the PCB's 7.4V screw terminal

Schematic Diagram & Component List

Component	Specifications	Purpose	Location
NUCLEO-H745ZI-Q	Dual-core ARM Cortex-M7/M4	Main controller	Shield base board
Arduino Nano	ATmega328P	Encoder preprocessing	On shield PCB
nRF24L01	2.4GHz wireless module	GPS data reception	On shield PCB
MPU6050	6-DOF IMU	Orientation tracking	On shield PCB
GM 25-370	12V DC motor with encoder	Drive system	External (pins on PCB)
MCP2515	CAN controller	CAN-SPI interface	On shield PCB
TJA1051	CAN transceiver	CAN physical layer	On shield PCB
MG996R	Servo motor	Steering control	External (pins on PCB)
30A ESC	Electronic speed controller	Motor drive control	External (pins on PCB)
HW-508	Passive buzzer	Audio feedback	On shield PCB
LM2596 (x2)	DC-DC Step Down	5V and 3.3V regulation	External (recommended)