Data Sheet

Revision 2.0 Page 24 of 74
nRF24L01 Product Specification
7 Enhanced ShockBurst™
Enhanced ShockBurst™ is a packet based data link layer. It features automatic packet assembly and tim-
ing, automatic acknowledgement and re-transmissions of packets. Enhanced ShockBurst™ enables the
implementation of ultra low power, high performance communication with low cost host microcontrollers.
The features enable significant improvements of power efficiency for bi-directional and uni-directional sys-
tems, without adding complexity on the host controller side.
7.1 Features
The main features of Enhanced ShockBurst™ are:
• 1 to 32 bytes dynamic payload length
• Automatic packet handling
• Auto packet transaction handling
X Auto Acknowledgement
X Auto retransmit
• 6 data pipe MultiCeiver™ for 1:6 star networks
7.2 Enhanced ShockBurst™ overview
Enhanced ShockBurst™ uses ShockBurst™ for automatic packet handling and timing. During transmit,
ShockBurst™ assembles the packet and clocks the bits in the data packet into the transmitter for transmis-
sion. During receive, ShockBurst™ constantly searches for a valid address in the demodulated signal.
When ShockBurst™ finds a valid address, it processes the rest of the packet and validates it by CRC. If
the packet is valid the payload is moved into the RX FIFO. The high speed bit handling and timing is con-
trolled by ShockBurst™.
Enhanced ShockBurst™ features automatic packet transaction handling that enables the implementation
of a reliable bi-directional data link. An Enhanced ShockBurst™ packet transaction is a packet exchange
between to transceivers, where one transceiver is the Primary Receiver (PRX) and the other is the Primary
Transmitter (PTX). An Enhanced ShockBurst™ packet transaction is always initiated by a packet transmis-
sion from the PTX, the transaction is complete when the PTX has received an acknowledgment packet
(ACK packet) from the PRX.
The automatic packet transaction handling works as follows:
• The user initiates the transaction by transmitting a data packet from the PTX to the PRX. Enhanced
ShockBurst™ automatically sets the PTX in receive mode to wait for the ack packet.
• If the packet is received by the PRX, Enhanced ShockBurst™ automatically assembles and trans-
mits an acknowledgment packet (ACK packet) to the PTX before returning to receive mode
• If the PTX does not receive the ACK packet within a set time, Enhanced ShockBurst™ will automat-
ically retransmit the original data packet and set the PTX in receive mode to wait for the ACK packet
The PRX can attach user data to the ACK packet enabling a bi-directional data link. The Enhanced Shock-
Burst™ is highly configurable; it is possible to configure parameters such as maximum number of retrans-
mits and the delay from one transmission to the next retransmission. All automatic handling is done without
involvement of the MCU.
Section 7.3 on page 25
gives a description of the Enhanced ShockBurst packet format, section 7.4 on
page 26 describes autmatic packet handling, section 7.5 on page 28 describes automatic packet transac-
tion handling, section 7.6 on page 31
provides flowcharts for PTX and PRX operation.