Data Sheet

Revision 2.0 Page 32 of 74
nRF24L01 Product Specification
checks if the NO_ACK flag is set. If it is not set, the nRF24L01 enters RX mode to receive an ACK packet. If
the received ACK packet is empty, only the TX_DS IRQ is asserted. If the ACK packet contains a payload,
both TX_DS IRQ and RX_DR IRQ are asserted simultaneously before nRF24L01 returns to standby-I
mode.
If the ACK packet is not received before timeout occurs, the nRF24L01 returns to standby-I mode. It stays
in standby-I mode until the ARD has elapsed. If the number of retransmits has not reached the ARC, the
nRF24L01 enters TX mode and transmits the last packet once more.
While executing the Auto Retransmit feature, the number of retransmits can reach the maximum number
defined in ARC. If this happens, the nRF24L01 asserts the MAX_RT IRQ and returns to standby-I mode.
If the CE is high and the TX FIFO is empty, the nRF24L01 enters Standby-II mode.