Datasheet

32.5.7 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.

32.5.8 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.

32.5.9 Analog Connections

Not applicable.

32.5.10 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 (32.8.1.6 PADCAL) register.