14.4.8.5 Interrupt Handling

Two different interrupts indicate the PLL status (refer to the IRQ_STATUS register). IRQ_0 (PLL_LOCK) indicates that the PLL has locked. IRQ_1 (PLL_UNLOCK) interrupt indicates an unexpected unlock condition. A PLL_LOCK interrupt clears any preceding PLL_UNLOCK interrupt automatically and vice versa.

An IRQ_0 (PLL_LOCK) interrupt is supposed to occur in the following situations:

• State change from TRX_OFF to PLL_ON / RX_ON
• Frequency setting change in states PLL_ON / RX_ON
• A manually started center frequency calibration has been completed

All other PLL_LOCK interrupt events indicate that the PLL locked again after a prior unlock happened.

An IRQ_1 (PLL_UNLOCK) interrupt occurs in the following situations:

• A manually initiated center frequency calibration in states PLL_ON / (RX_ON)
• Frequency setting change in states PLL_ON / RX_ON

Any other occurrences of IRQ_1 (PLL_UNLOCK) indicate erroneous behavior and require checking of the actual device status.

PLL_LOCK and PLL_UNLOCK affect the behavior of the transceiver:

In states BUSY_TX and BUSY_TX_ARET the transmission is stopped and the transceiver returns into state PLL_ON. During BUSY_RX and BUSY_RX_AACK, the transceiver returns to state RX_ON and RX_AACK_ON, respectively, once the PLL has locked.