15.4.2.2 VLM Basic Operation

The Voltage Level Monitor function can be enabled by writing a ‘1’ to the VLM Interrupt Enable (VLM) bit in the Interrupt Enable Set (SUPC.INTENSET) register. The Voltage Level Monitor cannot be enabled separately from the brown-out detector. However, when the BOD is enabled, the Voltage Level Monitor can be configured by VLMLVL to be either OFF or to trigger at a certain percentage above the BOD level.

The VLM interrupt is configured by writing the VLM Configuration (VLMCFG) bits in SUPC.BODVDD. An interrupt is requested when the supply voltage falls below, rises above, or crosses the VLM threshold.

The VLM functionality will follow the BODVDD mode. If BODVDD is disabled (BODVDD.ENABLE=0), the VLM will not be enabled, even if the BODVDD.VLMLVL is not equal to 0. If BODVDD is using Sampled mode, the VLM will also be sampled.

When enabling VLM, the Interrupt flag will always be set if VLMCFG = 0x2, and may be set if VLMCFG is configured to FALLING (0x0) or RISING (0x1).

VLM Interrupts are generated on events that occur after VLMCFG is configured. E.g., if the VLM is already detecting a voltage that is too low, changing setting to FALLING will not result in an interrupt. Therefore, it is recommended to read the STATUS.VLM bit after configuring VLMCFG to determine the current state.

In addition, the Interrupt flag must be cleared, as it may contain old information.

The VLM threshold is defined by writing the VLM Level (VLMLVL) bits in SUPC.BODVDD.