Data Sheet

Revision 2.0 Page 25 of 74
nRF24L01 Product Specification
7.3 Enhanced Shockburst™ packet format
The format of the Enhanced ShockBurst™ packet is described in this chapter. The Enhanched Shock-
Burst™ packet contains a preamble field, address field, packet control field, payload field and a CRC field.
Figure 4. on page 25
shows the packet format with MSB to the left.
Figure 4. An Enhanced ShockBurst™ packet with payload (0-32 bytes)
7.3.1 Preamble
The preamble is a bit sequence used to detect 0 and 1 levels in the receiver. The preamble is one byte
long and is either 01010101 or 10101010. If the first bit in the address is 1 the preamble is automatically
set to 10101010 and if the first bit is 0 the preamble is automatically set to 01010101. This is done to
ensure there are enough transitions in the preamble to stabilize the receiver.
7.3.2 Address
This is the address for the receiver. An address ensures that the correct packet are detected by the
receiver. The address field can be configured to be 3, 4 or, 5 bytes long with the AW register.
Note: Addresses where the level shifts only one time (that is, 000FFFFFFF) can often be detected in
noise and can give a false detection, which may give a raised Packet-Error-Rate. Addresses
as a continuation of the preamble (hi-low toggling) raises the Packet-Error-Rate.
7.3.3 Packet Control Field
Figure 5 shows the format of the 9 bit packet control field, MSB to the left.
Figure 5. Packet control field
The packet control field contains a 6 bit payload length field, a 2 bit PID (Packet Identity) field and, a 1 bit
NO_ACK flag.
7.3.3.1 Payload length
This 6 bit field specifies the length of the payload in bytes. The length of the payload can be from 0 to 32
bytes.
Preamble 1 byte Address 3-5 byte
9 bit
Payload 0 - 32 byte
CRC 1-2
byte
Packet Control Field
NO_ACK 1bitPID 2bitPayload length 6bit