3.1.3 Audio Sample Resolutions

The CP2615 can be configured to support any one of the following stereo Playback/Record modes:

• Playback and Record: 16-bit resolution

• Playback only: 24-bit or 16-bit resolution

• Record only: 24-bit or 16-bit resolution

3.1.4 Audio Endpoint Synchronizations

USB audio endpoint synchronization is defined in Table 5.12 Synchronization Characteristics of the Universal Serial Bus Specification

Revision 2.0. The CP2615 supports the synchronous or asynchronous endpoint synchronization methods for all input and output

streaming configurations. In synchronous mode, the CP2615 adjusts the frequency of I2S_MCLK and I2S_LRCLK to match the rate at

which Start-of-Frame (SOF) packets are received from the USB host. In asynchronous mode, the CP2615 does not adjust the I2S

clocks and instead relies on the USB host to provide the synchronization based on implicit feedback from the input endpoint.

3.2 USB Function Controller and Transceiver

The Universal Serial Bus (USB) function controller in the CP2615 is a USB 2.0 compliant full-speed device with integrated transceiver

and on-chip matching and pullup resistors. The USB function controller manages all control, audio, HID, and IO interface transfers be-

tween the USB host and the CP2615.

3.2.1 Endpoint Usage

The USB endpoints are allocated as follows:

Table 3.2. USB Endpoint Allocations

Endpoint

Function

0

USB control

1

HID interface

2

Serial I/O interface

3

Audio streaming (configurable)

3.2.1.1 USB Control Endpoint

The USB control endpoint is used for enumeration and normal USB control functions.

3.2.1.2 HID Interface Endpoint

The HID endpoint is an interrupt IN endpoint that is used to report Consumer Control (i.e. volume up, volume down, etc.) button

presses.

3.2.1.3 Serial I/O Interface Endpoint

The Serial I/O endpoint is a bidirectional bulk interface that transfers either serial pass-through data with the CP2615 UART or I/O Pro-

tocol messages. A host application can use this interface to communicate with external devices or to ineract with CP2615 general pur-

pose I/O.

3.2.1.4 Audio Streaming Endpoint

This is an isochronous unidirectional or bi-directional audio streaming endpoint that carries USB digital audio data between the USB

host and the CP2615. The audio streaming interface has several possible configurations.

CP2615 Data Sheet

Functional Description

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