SLAM AGV Control & Power Distribution Board

Overview

This project consists of a custom-designed PCB (PENTASLAM_PCB8) that serves as the main power and communication interface between a Raspberry Pi and various peripherals essential for operating a SLAM-based Autonomous Guided Vehicle (AGV). The goal of this board is to ensure reliable communication and power delivery between devices while offloading power demands from the Raspberry Pi, improving stability and safety.

Core Functional Blocks of the Board

1. USB-C Connection (Primary Interface to Raspberry Pi)

• Purpose: Provides a single, unified connection to the Raspberry Pi for data communication between multiple peripherals and the Pi.
• Functionality:
• Data Path: USB-C connects to a USB Hub Controller IC (FT232RL-REEL), expanding the single USB port on the Pi into multiple downstream ports.

2. USB Hub (Multi-Port Expansion)

• Purpose: Allows connection of multiple USB devices through a single USB port on the Raspberry Pi.
• Details:
• Offers three downstream USB-A ports on the PCB for devices like:
• LIDAR Sensor (e.g., RPLIDAR A1M8)
• Other USB peripherals as needed
• Ensures data routing through the USB Hub IC to the Raspberry Pi.
• Provides independent 5V power to peripherals via onboard regulators rather than relying on the Pi’s limited 5V USB supply.

3. USB to UART Bridge

• Purpose: Provides serial communication between the Raspberry Pi and the STM32 microcontroller for sending commands and receiving encoder feedback.
• Details:
• IC : FTDI FT232RL
• Enables robust UART communication for:
• Motor control commands from Pi to STM32.
• Encoder and status data from STM32 to Pi.

4. STM32 Microcontroller Subsystem

• Purpose: Handles low-level motor control and encoder feedback independently from the Raspberry Pi.
• Functionality:
• Reads quadrature encoder inputs to track wheel positions and speed.
• Drives motor control signals to the L298 motor driver IC for differential drive control.
• Acts as an intelligent slave to the Pi, offloading time-sensitive motor control from the higher-level SLAM software stack.

5. Motor Driver (L298 Dual H-Bridge)

• Purpose: Drives the AGV’s left and right motors for differential steering.
• Details:
• Powered via dedicated 5V or 12V rail.
• Controlled via PWM and direction pins from STM32.
• Capable of driving motors with encoder feedback for closed-loop control.

6. Power Management System

• Purpose: Provides isolated, stable power to the various subsystems, decoupled from the Raspberry Pi’s onboard 5V rail.
• Details:
• Dual 5V LDOs:
• One supplies Raspberry Pi exclusively.
• One supplies USB peripherals and USB hub chip.
• 3.3V LDO supplies STM32 and USB Hub IC’s internal logic.
• USB-A ports powered independently to protect the Raspberry Pi from overcurrent situations.