USB Host Controller (UHC) - Prerequisites

Common prerequisites for all USB hosts.

This module is based on USB host stack full interrupt driven and supporting Sleep manager sleepmgr. For AVR and SAM3/4 devices the Clock Management clock services is supported. For SAMD21 devices the asfdoc_sam0_system_clock_group clock driver is supported.

The following procedure must be executed to setup the project correctly:

• Specify the clock configuration:
  • UC3 and SAM3/4 devices without USB high speed support need 48MHz clock input.
    You must use a PLL and an external OSC.
  • UC3 and SAM3/4 devices with USB high speed support need 12MHz clock input.
    You must use an external OSC.
  • UC3 devices with USBC hardware need CPU frequency higher than 25MHz.
  • SAMD21 devices without USB high speed support need 48MHz clock input.
    You must use a DFLL and an external OSC.
• In conf_board.h, the define CONF_BOARD_USB_PORT must be added to enable USB lines. (Not mandatory for all boards)
• Enable interrupts
• Initialize the clock service

The usage of Sleep manager sleepmgr service is optional, but recommended to reduce power consumption:

• Initialize the sleep manager service
• Activate sleep mode when the application is in IDLE state

conf_clock.h examples with USB support.

For AVR and SAM3/4 devices, add to the initialization code:

sysclk_init();
irq_initialize_vectors();
cpu_irq_enable();
board_init();
sleepmgr_init(); // Optional

For SAMD21 devices, add to the initialization code:

system_init();
irq_initialize_vectors();
cpu_irq_enable();
sleepmgr_init(); // Optional

Add to the main IDLE loop:

sleepmgr_enter_sleep(); // Optional