Data Sheet

Revision 2.0 Page 33 of 74
nRF24L01 Product Specification
7.6.2 PRX operation
The flowchart in Figure 9. shows how a nRF24L01 configured as a PRX behaves after entering standby-I
mode.
Figure 9. PRX operations in Enhanced ShockBurst™
You activate PRX mode by setting the CE pin high. The nRF24L01 enters RX mode and starts searching
for packets. If a packet is received and Auto Acknowledgement is enabled the nRF24L01 decides if this is
a new packet or a copy of a previously received packet. If the packet is new the payload is made available
in the RX FIFO and the RX_DR IRQ is asserted. If the last received packet from the transmitter is acknowl-
edged with an ACK packet with payload, the TX_DS IRQ indicates that the PTX received the ACK packet
Start Primary RX
Standby-I mode
Is CE =1?
TX mode
Transmit ACK
Is Auto
Acknowledgement
enabled?
RX mode
Yes
No
No_ACK set in
received packet?
Is the received
packet a new
packet?
TX Settling
Was there payload
attached with the last
ACK?
RX Settling
Pending
payload in TX
FIFO?
Put payload in RX
FIFO and
set RX_DR IRQ
Packet
received?
Yes
No
No
Yes
Is CE =1?
No
Yes
Put payload in RX
FIFO and
set RX_DR IRQ
Discard packet
No Yes
Yes
TX mode
Transmit ACK with
payload
TX Settling
No
Set TX_DS IRQ
Yes
No
YesNo
ShockBurst operation
RX FIFO
Full?
No
Yes