NRF24L01P-R datasheet(47/78 Pages) NORDIC

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nRF24L01+ Product Specification

7.8.4

Single transaction with ACK payload packet

Figure 21. is a scenario of the basic auto acknowledgement with payload. After the packet is transmitted by

the PTX and received by the PRX the ACK packet with payload is transmitted from the PRX to the PTX.

The RX_DR IRQ is asserted after the packet is received by the PRX, whereas on the PTX side the TX_DS

IRQ is asserted when the ACK packet is received by the PTX. On the PRX side, the TX_DS IRQ for the

ACK packet payload is asserted after a new packet from PTX is received. The position of the IRQ in Figure

21. shows where the MCU can respond to the interrupt.

Figure 21. TX/RX cycles with ACK Payload and the according interrupts

7.8.5

Single transaction with ACK payload packet and lost packet

Figure 22. is a scenario where the first packet is lost and a retransmission is needed before the RX_DR IRQ

on the PRX side is asserted. For the PTX both the TX_DS and RX_DR IRQ are asserted after the ACK

packet is received. After the second packet (PID=2) is received on the PRX side both the RX_DR (PID=2)

and TX_DS (ACK packet payload) IRQ are asserted.

Figure 22. TX/RX cycles and the according interrupts when the packet transmission fails

1 Radio Turn Around Delay

2 Uploading Payload for Ack Packet

3 Delay defined by MCU on PTX side,

≥ 130us

TX:PID=1

PTX

PRX

MCU PRX

UL1

MCU PTX

TX:PID=2

IRQ

ACK received

IRQ: TX DS (PID=1)

RX DR (ACK1PAY)

Transmit of packet

PID=2

Packet received.

IRQ: RX DR (PID=1)

Packet received.

IRQ: RX DR (PID=2)

TX DS (ACK1PAY)

IRQ

UL2

130us1

≥130us3

ACK1 PAY

TX:PID=1

PTX

PRX

MCU PRX

UL1

MCU PTX

130us1

TX:PID=1

ARD

No address detected.

RX off to save current

Retransmit of packet

PID=1

ACK received

IRQ: TX DS (PID=1)

RX DR (ACK1PAY)

TX:PID=2

ACK1 PAY

Packet received.

IRQ: RX DR (PID=2)

TX DS (ACK1PAY)

Auto retransmit delay

elapsed

130us1

Packet PID=1 lost

during transmission

Packet received.

IRQ: RX DR (PID=1)

UL2

IRQ

≥130us3

1 Radio Turn Around Delay

2 Uploading Paylod for Ack Packet

3 Delay defined by MCU on PTX side,

≥ 130us

NRF24L01P-R Datenblatt(PDF) 47 Page - Nordic Semiconductor

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