A number of built-in alarms are available to monitor internal events. Several types of alarms and upsets are detected by this feature:
- Serializer FIFO alarm (FIFO overflow or
underflow)
- Serializer PLL is not locked
- JESD204C link is enabled, but not transmitting data (not in the data transmission state)
- SYSREF causes internal clocks to be realigned
- An upset that impacts the NCO phase
- An upset that impacts the JESD204C clocks
When an alarm occurs, a bit for each specific alarm is set in ALM_STATUS. Each alarm bit remains set until the host system writes a 1 to clear the alarm. If the alarm type is not masked (see the
alarm mask register), then the alarm is also indicated by the ALARM register. The CALSTAT output pin can be configured as an alarm output that goes high when an alarm occurs; see the CAL_STATUS_SEL bit in the
calibration pin configuration register.