When using the transmit FIFO, the packet handler is capable of adding all of the programmed data to the header and packet length fields so that the CPU does not have to manage that information in the data payload. To transmit the data, the CPU writes the payload data and tells the device to send the data. In many applications, the Silicon Labs EZMac® PRO MAC layer can be used to interface with the FIFO and provide some higher level services such as packet forwarding and auto acknowledgment. In the example shown here it can be seen that the packet length is defined as three bytes. That tells the system that there are three bytes in the data field. By providing the capability to retransmit the current packet in the FIFO, the overall power consumption can be reduced even further. There is no SPI communication, CRC etc. required since it has already been completed. This is useful for things like beacon frames or in meter applications where the unit has to retransmit the code that no water has been used.