PRELIMINARY PRODUCT SPECIFICATION
nRF24L01 Single Chip 2.4 GHz Radio Transceiver
Figure 5: Example on how the acknowledgement addressing is done
An nRF24L01 configured as PTX with Enhanced ShockBurst™ enabled, will use the
ShockBurst™ feature to send a packet whenever the microcontroller wants to. After
the packet has been transmitted, nRF24L01 will switch on its receiver and expect an
acknowledgement to arrive from the terminating part. If this acknowledgement fails to
arrive, nRF24L01 will retransmit the same packet until it receives an
acknowledgement or the number of retries exceeds the number of allowed retries
given in the SETUP_RETR_ARC register. If the number of retries exceeds the
number of allowed retries, this will show in the STATUS register bit MAX_RT and
gives an interrupt.
Whenever an acknowledgement is received by an nRF24L01 it will consider the last
transmitted packet as delivered. It will then be cleared from the TX FIFO, and the
TX_DS IRQ source will be set high.
With Enhanced ShockBurst™ nRF24L01 offers the following benefits:
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Highly reduced current consumption due to short time on air and sharp timing
when operating with acknowledgement traffic
•
Lower system cost. Since the nRF24L01 handles all the high-speed link layer
operations, like re-transmission of lost packet and generating
acknowledgement to received packets, it is no need for hardware SPI on the
system microcontroller to interface the nRF24L01. The interface can be done
by using general purpose IO pins on a low cost microcontroller where the SPI
is emulated in firmware. With the nRF24L01 this will be sufficient speed even
when running a bi-directional link.
•
•
Greatly reduced risk of “on-air” collisions due to short time on air
Easier firmware development since the link layer is integrated on chip
Nordic Semiconductor ASA - Vestre Rosten 81, N-7075 Tiller, Norway
Revision: 1.1
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Phone +4772898900
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Fax +4772898989
November 2005
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