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Human Machine Interface (HMI) for Diagnostic Tool

Many types of commercial and industrial equipment, such as HVAC or air conditioning systems, offer post-sale diagnostic services that require some type of diagnostic tool. The growing trend is to eliminate printed user manuals and instructions about how to operate the tool and run diagnostic tests. Instead, an HMI command center can be embedded in the diagnostic tool to display the latest information for easy access by the technician.

Design Challenges

To add or upgrade a diagnostic tool’s HMI command center with a large touchscreen and graphical interface that enables easy navigation through a variety of functions and features, you may need:

  • A high-performance microcontroller (MCU) or possibly even a microprocessor (MPU) to drive a larger screen with a high-resolution color graphics display
  • Expansive data storage, such as DRAM, to render graphics
  • An easy-to-use embedded graphics tool to shorten your development time
  • Wired and wireless (Wi-Fi) connectivity between the equipment and the control center for:
    • Diagnosing or updating the latest firmware on the equipment
    • Getting access to the database on the command center

Block Diagram

The block diagram below illustrates how to implement a diagnostic tool with a graphical HMI command center for diagnosing an air conditioning system as the example end equipment.

Recommended Solutions

32-bit Microcontrollers (MCUs)

  • PIC32MZ DA Family:
    • High-performance MCU (330 DMIPS) with integrated DRAM to drive larger LCD screens
    • Advanced graphics capabilities:
      • Three-layer graphics controller capable of driving 24-bit color WVGA
      • High-performance 2D Graphics Processing Unit (GPU)
    • High memory density:
      • 32 MB integrated or 128 MB externally addressable DDR2 DRAM  
      • Up to 2 MB Flash and 640 KB RAM
    • Well suited for embedded graphics and HMI applications

Wireless Connectivity

  • ATWINC3400 (Bluetooth® Low Energy/Wi-Fi®): IEEE® 802.11 b/g/n network controller with integrated Bluetooth Low Energy module
  • ATWINC1500 (Wi-Fi): IEEE 802.11 b/g/n SmartConnect IoT module

CAN Transceiver

  • ATA6561: High-speed CAN FD transceiver with standby mode and VIO Pin

maXTouch® Touchscreen Controller

  • ATMXT Touchscreen Controller Family: Leading projected capacitive touch sensing technology for touchscreens and touchpads, with a portfolio covering solutions for all touch surfaces and screens up to 24” in diagonal size

Step-Down Converter/LEO Linear Voltage Regulators

  • MIC29302: high-current, high-accuracy, low dropout voltage regulator
  • MIC3775: 750 mA low dropout linear voltage regulator
  • MCP1703: CMOS, low dropout voltage regulator with 250 mA maximum output current

Secure Element

  • ATECC608A: JIL “high” rated cryptographic co-processor with secure hardware-based key storage

MEMS Clock (Optional)

  • DSC612 or DSC613: MEMS clock generators that cover a wide frequency range without requiring an external crystal and provide a true single-chip, multi-output solution for MCU-based systems

Embedded Graphical User Interfaces (GUI) Development Tool

  • MPLAB® Harmony Graphics Suite (MHGS): Powerful and free tools for use with Microchip’s MCUs and MPUs to reduce embedded graphics development cost, time and risk
    • Easy-to-Use “Display Manager” allows you to visualize display timing and generate your own display controller driver, with minimal to no code writing
    • Extensive graphics library to support different colors and text (strings, fonts, multi-lingual)