What is the exact use of presence of Write strobe data in AXI4

• The presence of a write strobe helps save the energy and time of the master.

• To understand this, consider a scenario where the write strobe is not present and data needs to be transferred.

• The usual way of transferring happens from the LSB side of the bus

• Consider the following example where a 32-bit data bus is present, and data is being written without using a write strobe signal.

• If the first transferred write data is FF and the second transferred write data is 00, the LSB byte lane of the bus should change from FF to 00.

• This change requires a switching operation of transistors, consuming more transient power.

• Therefore, to reduce this power consumption, write strobes are introduced.

• The above figure illustrates the presence of previous data (considered as the 1st data transfer) and new data (considered as the 2nd data transfer) on the 32-bit data bus.

• When the master sends the new data, it checks the bus for the nearest data (from the previous data) and validates the write strobe data of the byte lane. This approach reduces energy consumption.

Why Read strobe is not present in AXI4

• the master itself knows on which byte lane of the slave the data is valid, and the responsibility of the master is to extract that data from the slave.

• The reason behind this is that the addition of a read strobe would require extra energy, which, in turn, consumes more power.

• Since slaves are designed to consume less power and have minimal control, the master controls the entire transfer in reading.