33.6.3.6 Host Inter-Character Spacing
When configured as Host, inter-character spacing can be increased by writing a non-zero value to the Inter-Character Spacing bit field in the Control C register (CTRLC.ICSPACE). When non-zero, CTRLC.ICSPACE represents the minimum number of baud cycles that the SCK clock line does not toggle and the next character is stalled.
The figure gives an example for CTRLC.ICSPACE = 4; In this case, the SCK is inactive for 4 baud cycles.