48.6.1.2 SPDIF Transmitter Data Rate

The SPDIFTX sends symbols at the rate of GCLK. Thus the data rate is managed by the GCLK clock generated by the PMC.

Each bit to send is converted into 2 symbols. Thus a frame has a length of 128 symbols. In order to respect a sample rate of F_S, the frequency of GCLK must be F_GCLK=128 × F_S. GCLK must be derived from an audio clock.