3.3.9 USART with Fractional Baud Rate Configuration on SAM D21 Curiosity Nano Evaluation Kit

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Description

This application demonstrates the basic functionality of USART communication between two SAM D21 Curiosity Nano Evaluation Kits with the fractional baud rate of 11000. The host and client can send/receive data with the help of serial consoles.

Modules/Technology Used

  • Peripheral Modules
    • NVMCTRL
    • EVSYS
    • SERCOM

Hardware Used

Software/Tools Used

This project has been verified to work with the following versions of software tools:

Refer Project Manifest present in harmony-manifest-success.yml under the project folder firmware/src/config/sam_d21_cnano.

  • Refer the Release Notes to know the MPLAB X IDE and MCC Plugin version.
  • Any Serial Terminal application, such as Tera Term terminal application.

Because Microchip regularly updates tools, occasionally issue(s) could be discovered while using the newer versions of the tools. If the project does not seem to work and version incompatibility is suspected. It is recommended to double-check and use the same versions that the project was tested with. To download original version of MPLAB Harmony v3 packages, refer to document How to Use the MPLAB Harmony v3 Project Manifest Feature (DS90003305).

Setup

  • Connect the Type-A male to Micro-B USB cable to Micro-B DEBUG USB port (J900) to program and debug the SAM D21 Curiosity Nano Evaluation Kit.
  • Connect the pins PA16 of one board to PA17 of another board and vice versa. Connect GND pin of the two boards as shown in the below figure.

Programming Hex File

The pre-built hex file can be programmed by following the below steps.

Steps to program the hex file:
  • Open MPLAB X IDE.
  • Close all existing projects in IDE, if any project is opened.
  • Go to File -> Import -> Hex/ELF File.
  • In the Import Image File window,
    1. Create Prebuilt Project,
      • Click the Browse button to select the prebuilt hex file.
      • Select Device as ATSAMD21G17D.
      • Ensure the proper tool is selected under Hardware Tool and click on Next button.
    2. Select Project Name and Folder,
      • Select appropriate project name and folder and click on Finish button
  • In MPLAB X IDE, click on Make and Program Device button to program the device.
  • Follow the steps in Running the Demo section below.

Programming/Debugging Application Project

  • Open the project (sam_d21_cnano_usart_fractional_baud\firmware\sam_d21_cnano.X) in MPLAB X IDE
  • Ensure SAM D21 Curiosity Nano is selected as hardware tool to program/debug the application
  • Build the code and program both the devices by clicking on the Make and Program button in MPLAB X IDE tool bar
  • Follow the steps in Running the Demo section below

Running the Demo

  • Open two Tera Term terminal applications on the PC (from the Windows Start menu by pressing the Start button).
  • Set the baud rate to 9600 on both the terminals.
  • Reset or power cycle both the devices.
  • Enter any data on one terminal (host side) and it will display on the other terminal (client side).
    Note: Either of the boards can act as the host, while the other acts as the client.
  • Below diagrams show the sample output logs displayed on command prompt.
    Figure 3-3. Host Side
    Figure 3-4. Client Side

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