Interframe spacing (IFS)

nRF5340 Product Specification

Interframe spacing (IFS) is defined as the time, in microseconds, between two consecutive packets, starting from when the end of the last bit of the previous packet is received, to the beginning of the first bit of the subsequent packet that is transmitted.

RADIO can enforce this interval, as specified in the TIFS register, as long as the TIFS register is not specified to be shorter than RADIO's turnaround time (i.e. the time needed to switch off the receiver, and then switch the transmitter back on). The TIFS register can be written any time before the last bit on air is received.

This timing is illustrated in the following figure.
Figure 14. IFS timing detail

IFS timing detail
The TIFS duration starts after the last bit on air (just before the END event), and elapses with the first bit being transmitted on air (just after READY event).

TIFS is only enforced if the shortcuts END to DISABLE and DISABLED to TXEN or END to DISABLE and DISABLED to RXEN are enabled.

TIFS is qualified for use in IEEE 802.15.4 250kbps mode, Bluetooth Low Energy Long Range (125 kbps and 500 kbps) modes, and Bluetooth Low Energy 1 Mbps and 2 Mbps modes, using the default ramp-up mode.

SHORTS and TIFS registers are not double-buffered, and can be updated at any point before the last bit on air is received. The MODE register is double-buffered and sampled at the TXEN or RXEN task.