Introduction
Nordic Enhanced ShockBurst (NESB) is a basic protocol which supports two-way data packet communication with the following features:
- Packet acknowledgement
- Automatic retransmission of lost packets
- Variable packet length
It provides a simple bidirectional data link in which a device can act as either primary transmitter (PTX) or as primary receiver (PRX).
Packet transaction
A simple packet transaction involves the PTX device sending a packet which is received and acknowledged by the PRX device. Once the PTX device receives the acknowledge, a new packet can be sent or both devices return to an "Idle" state.
If an ACK sent by the PRX device does not reach the PTX device, the PTX will assume that the packet was lost and will retransmit the packet considering a retransmission delay set by the user. This will continue to happen until an ACK is received or until the maximum number of retransmission attempts is reached.
In simple terms, the NESB command handlers can be described as extensions of the generic command handlers in which the LRF can automatically switch between Tx and Rx, or vice versa. The time that it takes to switch between these to states is called the turnaround time.
Packet format
The NESB protocol has a specific over-the-air packet format in which all data is assumed to be transmitted and received most-significant-bit first.
Additionally, the NESB header is divided into three fields.
