Getting Started with USB on SAM MCUs Using MPLAB® Harmony v3: Step 3

Last modified by Microchip on 2023/11/09 09:08

Configure Clocks, Pins, and Application Tasks

Configure Clocks

Open the Clock Configuration pane by navigating to MHC > Tools > Clock Configuration.

Open Clock Configuration

Figure 1: Open Clock Configuration

Switch MOSCSEL to Main Crystal.​

Note: USB requires an accurate clock for operation and cannot run on the Main RC oscillator.

Clock Configuration

Figure 2: Clock Configuration

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Configure Pins

Open the Pin Configuration pane by navigating to MHC > Tools > Pin Configuration.

Open Pin Configuration

Figure 3: Open Pin Configuration

Order the pins by Ports for ease of use.

Order by Ports

Figure 4: Order by Ports

The LED on the I/O1 Xplained Pro is connected to pin PA0.

  • Set the function to GPIO.

  • Name this pin as "LED".
  • Set the direction to Out.
  • Set the latch to High.

TWIHS pins, PA3 and PA4, need to be set to the correct function.

  • For PA3, set function to TWIHS0_TWD0.
  • For PA4, set function to TWIHS0_TWCK0.
LED and TWIHS Pin Config

Figure 5: LED and TWIHS Pin Config

The LED on the SAM E70 Xplained is connected to pin PC8.

SAM E70 Xplained User LED Schematic

Figure 6: SAM E70 Xplained User LED Schematic

  • Set the function to GPIO.
  • Name this pin as "USB_LED".
  • Set the direction to Out.
  • Set the latch to High.
User LED Config

Figure 7: User LED Config

Note: The LEDs on the SAM E70 Xplained and the I/O1 Xplained Pro are active low, so, they are turned off by default by configuring the latch value to logic High.

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Add and Configure Application Tasks

Go to the Project Graph and click on the Core module.

Under Configuration Options, you will find that MHC automatically generates a default application named app. Set the Number of Applications spinbox to 3 and configure each of them as follows:

  • Expand Application 0 Configuration and rename the default application name to "app_sensor".

  • Expand Application 1 Configuration and rename the default application name to "app_eeprom".
  • Expand Application 2 Configuration and rename the default application name to "app_usb".
Configure Application Tasks

Figure 8: Configure Application Tasks

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