Digital Audio Ports
====================

+-----+----------+------------------------------+--------------+-------------+
| Pin | Signal   | Description                  | type         | I/O         |
+=====+==========+==============================+==============+=============+
| 83  | SSI1_INT | Interrupt                    |              |             |
| 89  | SSI2_INT |                              |              |             |
+-----+----------+------------------------------+--------------+-------------+
| 84  | SSI1_RXD | Receive serial data          |              |             |
| 90  | SSI2_RXD |                              |              |             |
+-----+----------+------------------------------+--------------+-------------+
| 85  | SSI1_TXD | Transmit serial data         |              |             |
| 91  | SSI2_TXD |                              |              |             |
+-----+----------+------------------------------+--------------+-------------+
| 86  | SSI1_CLK | Serial clock                 |              |             |
| 92  | SSI2_CLK |                              |              |             |
+-----+----------+------------------------------+--------------+-------------+
| 87  | SSI1_FS  | Frame Sync                   |              |             |
| 93  | SSI2_FS  |                              |              |             |
+-----+----------+------------------------------+--------------+-------------+
| **Module**     | **Remark**                                                |
+----------------+-----------------------------------------------------------+
| TX28S, TX48    | Only one SSI port available, SSI2 pins are not connected. |
+----------------+-----------------------------------------------------------+
| TX28, TX28S    | On this module the SSI is a half-duplex serial port.      |
+----------------+-----------------------------------------------------------+

The SSI is a full-duplex, serial port that allows the chip to communicate with a variety of serial devices. These serial devices can be standard CODer-DECoder (CODECs), Digital Signal Processors (DSPs), microprocessors, peripherals, and popular industry audio CODECs that implement the inter-IC sound bus standard (I2S) standard.

SSI is typically used to transfer samples in a periodic manner. The SSI consists of independent transmitter and receiver sections with independent clock generation and frame synchronization.

Audio Codec example:

.. figure:: ../images/digital_audio_ports.png
   :align: center