Datasheet

Table Of Contents
38.5.6 Events
Not applicable.
38.5.7 Debug Operation
When the CPU is halted in debug mode the USB peripheral continues normal operation. If the USB
peripheral is configured in a way that requires it to be periodically serviced by the CPU through interrupts
or similar, improper operation or data loss may result during debugging.
38.5.8 Register Access Protection
Registers with write access can be optionally write-protected by the Peripheral Access Controller (PAC),
except for the following:
Device Interrupt Flag (INTFLAG) register
Endpoint Interrupt Flag (EPINTFLAG) register
Host Interrupt Flag (INTFLAG) register
Pipe Interrupt Flag (PINTFLAG) register
Note:  Optional write protection is indicated by the "PAC Write Protection" property in the register
description.
Write protection does not apply for accesses through an external debugger.
38.5.9 Analog Connections
Not applicable.
38.5.10 Calibration
The output drivers for the DP/DM USB line interface can be fine tuned with calibration values from
production tests. The calibration values must be loaded from the NVM Software Calibration Area into the
USB Pad Calibration register (PADCAL) by software, before enabling the USB, to achieve the specified
accuracy. Refer to NVM Software Calibration Area Mapping for further details.
For details on Pad Calibration, refer to Pad Calibration (38.8.1.6 PADCAL) register.
38.6 Functional Description
38.6.1 USB General Operation
38.6.1.1 Initialization
After a hardware reset, the USB is disabled. The user should first enable the USB (CTRLA.ENABLE) in
either device mode or host mode (CTRLA.MODE).
SAM D5x/E5x Family Data Sheet
USB – Universal Serial Bus
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1112