7 Differences Between I2SC and SSC

Though SSC and I2SC are synchronous serial links commonly used for digital audio communication, there are differences between the two peripherals based on their implementation and configurability. Users can choose SSC or I2SC for the application based on the peripheral’s capability, the connected device’s requirements and the I/O pin availability.
  1. I2SC only supports the I2S protocol, whereas SSC is a highly configurable peripheral that supports the I2S protocol among others. For example, the data transfer delay is fixed to 1-bit clock cycle in I2SC, whereas in SSC it is configurable. This helps to interface SAMA5D2 with different types of codec devices that use different frame formats than the standard I2S frame format.
  2. The I2SC in SAMA5D2 can be used only with a single slave or a single master. It does not support the TDM feature, which is used to interface with multiple I2S devices. SSC can be configured to interface with multiple I2S devices on a single bus.
  3. The I2SC has an internal clock divider for master clock output using a dedicated master clock pin (I2SCMCK) and can be clocked with the Audio PLL output using the GCLK interface. However, the SSC cannot be clocked with the GCLK interface; it is only clocked by the system clock (MCK). To clock the SSC module with the Audio PLL clock, the system clock should also be clocked with the Audio PLL. This drawback is addressed in the SAMA5D2 product, where a dedicated pin is provided to the Audio PLL (CLK_AUDIO) to output the master clock frequency required for the audio devices connected to the SSC. The SSC can sample the data based on TK/RK pins (timed based on CLK_AUDIO) while still being clocked by the MCK clock.
  4. SSC may be prone to channel swapping issues in cases where data transfer to the Transmit Holding Register (THR) through DMA is triggered by the falling/rising edge of the TF/RF signal due to a delay in DMA transfer. This issue may not be encountered in I2SC since the data transfer through DMA is always triggered by TXRDY/RXRDY signals.