NRF24L01P-R datasheet(28/78 Pages) NORDIC

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nRF24L01+ Product Specification

7.3

Enhanced Shockburst™ packet format

The format of the Enhanced ShockBurst™ packet is described in this section. The Enhanced Shock-

Burst™ packet contains a preamble, address, packet control, payload and CRC field. Figure 5. shows the

packet format with MSB to the left.

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

7.3.1

Preamble

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.

7.3.2

Address

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.

7.3.3

Packet control field

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

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.

P ream ble 1 by te

A ddre s s 3-5 byte

9 bit

P a yload 0 - 32 by te

CR C 1 -2

byte

P a c k et C ontro l F ield

NO_ACK 1bit

PID 2bit

Payload length 6bit

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