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nRF24L01+ Product Specification

7.3Enhanced Shockburstpacket format

The format of the Enhanced ShockBurst™ packet is described in this section. The Enhanced ShockBurst™ packet contains a preamble, address, packet control, payload and CRC field. Figure 5. shows the packet format with MSB to the left.

P re a m b le 1 b y te

A d d re s s 3 -5 b y te

P a c k e t C o n tro l F ie ld 9 b it

P a y lo a d 0 - 3 2 b y te

C R C 1 -2

b y te

 

 

 

 

 

 

 

 

 

Figure 5. An Enhanced ShockBurst™ packet with payload (0-32 bytes)

7.3.1Preamble

The preamble is a bit sequence used to synchronize the receivers demodulator to the incoming bit stream. 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.

7.3.2Address

This is the address for the receiver. An address ensures that the packet is detected and received by the correct receiver, preventing accidental cross talk between multiple nRF24L01+ systems. You can configure the address field width in the AW register to be 3, 4 or 5 bytes, see Table 28. on page 63.

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) also raises the Packet Error Rate.

7.3.3Packet control field

Figure 6. shows the format of the 9 bit packet control field, MSB to the left.

Payload length 6bit

PID 2bit

NO_ACK 1bit

 

 

 

Figure 6. 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.

Revision 1.0

Page 28 of 78

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