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Hardware Components

This section details the various hardware components that make up the Modular Mechanica system.

Moducard Hardware​

Backplane​

The backplane is the central PCB where all cards are inserted. It serves as the main connection point and power distribution hub for the entire system.

Features:​

  • DIN41612 connectors - 3 rows × 32 pins for card insertion
  • Power distribution - 12V standby and Vbat (12-48V)
  • Communication buses - CAN, GPIO, USB
  • Built-in USB hub - For each card
  • GPIO lines - Shared (C) and sibling (L/R) connections

DIN41612 Connector Pinout:​

  • ROW A - CAN1, CAN2, USB D+, GPIO R (1-4), VBAT 48V, 12V stdby, GND
  • ROW B - CAN1, CAN2, GPIO C (1-4), VBAT 48V, 12V stdby, GND
  • ROW C - CAN1, CAN2, USB D-, GPIO L (1-4), VBAT 48V, 12V stdby, GND

Card Types​

CPU Cards​

Serve as the main computing unit of the robot:

  • Raspberry Pi CM5 - Default option, cost-effective
  • NVIDIA Jetson - GPU acceleration (CUDA, deep learning)
  • Raspberry Pi 5 - Alternative option

Power Supply Units (PSU)​

Provide power distribution and protection:

  • Input: XT60 connector for LiPo batteries
  • Output: 12V standby and Vbat (12-48V)
  • Protection: Reverse current and overcurrent protection
  • Monitoring: Current and voltage measurement with reporting

Microcontroller Cards​

Handle control, data acquisition, and specialized functions:

  • Prototype Board - Arduino hat connector, MMS-Link and GPIO access, custom circuitry area
  • Navboard - Dedicated navigation board with integrated IMU and orientation sensors

MiniModucard System (MMS)​

MMS Modules​

Each MMS module contains a single main microcontroller that manages multiple hat modules:

Specifications:​

  • Microcontroller: STM32F405 (168 MHz)
  • Power supply: Integrated VIN → 5V converter with wide input voltage range
  • Programming: Built-in ST-Link programmer
  • Communication: Chainbus protocol for connecting hats

Hat Modules​

Hat modules are small boards inserted into MMS modules that contain the actual peripheral electronics.

Characteristics:​

  • Function-specific - Drivers, sensors, displays, buttons
  • Addressable - Each hat has a unique ID and type
  • Modular - Easy to add/remove functionality
  • Standardized - Compatible with Chainbus protocol

Common Hat Types:​

  1. Thermocouple Hat - 8-channel thermocouples with I2C/SPI communication
  2. Protocol Hat - Interface for I2C, SPI, UART protocols with level converters
  3. Relay Hat - 5-channel relays with 230AC clearance and creepage
  4. Stepper Driver Hat - Stepper motor driver with integrated buck converter

Chainbus Protocol​

Chainbus is the communication protocol that connects MMS modules to their hat modules.

Physical Connection:​

  • DIN41612 connector - 3 rows × 16 pins
  • ROW A - 16 raw GPIO lines (Altmode1–Altmode16)
  • ROW B - Digital bus: 8× address + I2C + SPI + UART
  • ROW C - Power supply: GND, +5V, BRD_VIN, +12V stdby

Communication Modes:​

  1. Chainbus Mode - Uses ROW B + ROW C for standard communication
  2. Altmode - Uses all three rows (A + B + C) for full GPIO access

Addressing System:​

  • Each hat has one address line
  • Addresses are passed through the chain with position-based addressing
  • MMS activates addrN to select the appropriate hat at position N

Power Budget​

Backplane Power Distribution:​

  • 12V standby output: 24W for 6-module rack (at 60°C)
  • 48V Vbat output: 108W for 6-module rack (at 60°C)
  • Individual pin current rating: 2A at 25°C, 1A at 70°C with 3× safety margin

DIN41612 Pin Current Ratings:​

  • Standard: 2A at 25°C, 1A at 70°C
  • Safety margin: ×3 for reliable operation