ESP32-LyraT V4.2 Getting Started Guide
======================================

This guide provides users with functional descriptions, configuration options for ESP32-LyraT V4.2 audio development board, as well as how to get started with the ESP32-LyraT board.

The ESP32-LyraT development board is a hardware platform designed for the dual-core ESP32 audio applications, e.g., Wi-Fi or BT audio speakers, speech-based remote controllers, smart-home appliances with audio functionality(ies), etc.

If you like to start using this board right now, go directly to section :ref:`get-started-esp32-lyrat-v4.2-start-development`.


What You Need
-------------

* 1 × :ref:`ESP32 LyraT V4.2 board <get-started-esp32-lyrat-v4.2-board>`
* 2 x 4-ohm speakers with Dupont female jumper wires or headphones with a 3.5 mm jack
* 2 x Micro-USB 2.0 cables, Type A to Micro B
* 1 × PC loaded with Windows, Linux or Mac OS


Overview
^^^^^^^^

The ESP32-LyraT V4.2 is an audio development board produced by `Espressif <https://espressif.com>`_ built around ESP32. It is intended for audio applications, by providing hardware for audio processing and additional RAM on top of what is already onboard of the ESP32 chip. The specific hardware includes:

* **ESP32-WROVER Module**
* **Audio Codec Chip**
* Dual **Microphones** on board
* **Headphone** input
* **2 x 3-watt Speaker** output
* Dual **Auxiliary Input**
* **MicroSD Card** slot (1 line or 4 lines)
* **Six buttons** (2 physical buttons and 4 touch buttons)
* **JTAG** header
* Integrated **USB-UART Bridge Chip**
* Li-ion **Battery-Charge Management**

The block diagram below presents main components of the ESP32-LyraT and interconnections between components.

.. figure:: ../../_static/esp32-lyrat-block-diagram.jpg
    :alt: ESP32 LyraT block diagram
    :figclass: align-center

    ESP32-LyraT Block Diagram


Functional Description
^^^^^^^^^^^^^^^^^^^^^^

The following list and figure describe key components, interfaces and controls of the ESP32-LyraT board.

ESP32-WROVER Module
    The ESP32-WROVER module contains ESP32 chip to provide Wi-Fi / BT connectivity and data processing power as well as integrates 32 Mbit SPI flash and 32 Mbit PSRAM for flexible data storage.
Green and Red LEDs
    Two general purpose LEDs controlled by **ESP32-WROVER Module** to indicate certain operation states of the audio application using dedicated API.
Function DIP Switch
    Used to configure function of GPIO12 to GPIO15 pins that are shared between devices, primarily between **JTAG Header** and **MicroSD Card**. By default, the **MicroSD Card** is enabled with all switches in *OFF* position. To enable the **JTAG Header** instead, switches in positions 3, 4, 5 and 6 should be put *ON*. If **JTAG** is not used and **MicroSD Card** is operated in the one-line mode, then GPIO12 and GPIO13 may be assigned to other functions. Please refer to `ESP32 LyraT V4.2 schematic`_ for more details.
JTAG Header
    Provides access to the **JTAG** interface of **ESP32-WROVER Module**. It may be used for debugging, application upload, as well as implementing several other functions, e.g., `Application Level Tracing <http://esp-idf.readthedocs.io/en/latest/api-reference/system/app_trace.html>`_. See :ref:`get-started-esp32-lyrat-v4.2-jtag-header` for pinout details. Before using **JTAG** signals to the header, **Function DIP Switch** should be enabled. Please note that when **JTAG** is in operation, **MicroSD Card** cannot be used and should be disconnected because some of JTAG signals are shared by both devices.
UART Header
    Serial port: provides access to the serial TX/RX signals between **ESP32-WROVER Module** and **USB-UART Bridge Chip**.
I2C Header
    Provides access to the I2C interface. Both **ESP32-WROVER Module** and **Audio Codec Chip** are connected to this interface. See :ref:`get-started-esp32-lyrat-v4.2-i2c-header` for pinout details.
MicroSD Card
    The development board supports a MicroSD card in SPI/1-bit/4-bit modes, and can store or play audio files in the MicroSD card. See :ref:`get-started-esp32-lyrat-v4.2-microsd-card-slot` for pinout details. Note that **JTAG** cannot be used and should be disconnected by setting **Function DIP Switch** when **MicroSD Card** is in operation, because some of signals are shared by both devices.
I2S Header
    Provides access to the I2S interface. Both **ESP32-WROVER Module** and **Audio Codec Chip** are connected to this interface. See :ref:`get-started-esp32-lyrat-v4.2-i2s-header` for pinout details.
Left Microphone
    Onboard microphone connected to IN1 of the **Audio Codec Chip**.
AUX Input
    Auxiliary input socket connected to IN2 (left and right channel) of the **Audio Codec Chip**. Use a 3.5 mm stereo jack to connect to this socket.
Headphone Output
    Output socket to connect headphones with a 3.5 mm stereo jack.

.. _get-started-esp32-lyrat-v4.2-board:

.. figure:: ../../_static/esp32-lyrat-v4.2-layout.jpg
    :alt: ESP32 LyraT V4.2 board layout
    :figclass: align-center

    ESP32-LyraT V4.2 Board Layout


Right Microphone
    Onboard microphone connected to IN1 of the **Audio Codec Chip**.
Left Speaker Output
    Output socket to connect 4 ohm speaker. The pins have a standard 2.54 mm / 0.1" pitch.
Right Speaker Output
    Output socket to connect 4 ohm speaker. The pins have a standard 2.54 mm / 0.1" pitch.
PA Chip
    A power amplifier used to amplify stereo audio signal from the **Audio Codec Chip** for driving two 4-ohm speakers.
Boot/Reset Press Keys
    Boot button: holding down the **Boot** button and momentarily pressing the **Reset** button to initiate the firmware download mode. Then you can download firmware through the serial port. Reset button: pressing this button alone resets the system.
Touch Pad Buttons
    Four touch pads labeled *Play*, *Sel*,  *Vol+* and *Vol-*. They are routed to **ESP32-WROVER Module** and intended for development and testing of a UI for audio applications using dedicated API.
Audio Codec Chip
    The Audio Codec Chip, `ES8388 <http://www.everest-semi.com/pdf/ES8388%20DS.pdf>`_, is a low power stereo audio codec with a headphone amplifier. It consists of 2-channel ADC, 2-channel DAC, microphone amplifier, headphone amplifier, digital sound effects, analog mixing and gain functions. It is interfaced with **ESP32-WROVER Module** over I2S and I2S buses to provide audio processing in hardware independently from the audio application.
EN Header
    Install a jumper on this header to enable automatic loading of application to the ESP32. Install or remove jumpers together on both IO0 and EN headers.
IO0 Header
    Install a jumper on this header to enable automatic loading of application to the ESP32. Install or remove jumpers together on both IO0 and EN headers.
Function Press Keys
    Two key labeled *Rec* and *Mode*. They are routed to **ESP32-WROVER Module** and intended for developing and testing a UI for audio applications using dedicated API.
USB-UART Bridge Chip
    A single chip USB-UART bridge provides up to 1 Mbps transfers rate.
USB-UART Port
    Functions as the communication interface between a PC and the ESP32 module.
USB Power Port
    Provides the power supply for the board.
Standby / Charging LEDs
    The **Standby** green LED indicates that power has been applied to the **Micro USB Port**. The **Charging** red LED indicates that a battery connected to the **Battery Socket** is being charged.
Battery Charger Chip
    Constant current & constant voltage linear charger for single cell lithium-ion batteries AP5056. Used for charging of a battery connected to the **Battery Socket** over the **Micro USB Port**.
Power On Switch
    Power on/off knob: toggling it to the left powers the board on; toggling it to the right powers the board off.
Battery Socket
    Two pins socket to connect a single cell Li-ion battery.
Power On LED
    Red LED indicating that **Power On Switch** is turned on.

    .. note::

        The **Power On Switch** does not affect / disconnect the Li-ion battery charging.


.. _get-started-esp32-lyrat-v4.2-setup-options:

Hardware Setup Options
^^^^^^^^^^^^^^^^^^^^^^

There are a couple of options to change the hardware configuration of the ESP32-LyraT board. The options are selectable with the **Function DIP Switch**.

Enable MicroSD Card in 1-wire Mode
""""""""""""""""""""""""""""""""""

+---------+-----------------+
|  DIP SW | Position        |
+=========+=================+
|    1    |    OFF          |
+---------+-----------------+
|    2    |    OFF          |
+---------+-----------------+
|    3    |    OFF          |
+---------+-----------------+
|    4    |    OFF          |
+---------+-----------------+
|    5    |    OFF          |
+---------+-----------------+
|    6    |    OFF          |
+---------+-----------------+
|    7    |    OFF :sup:`1` |
+---------+-----------------+
|    8    |    n/a          |
+---------+-----------------+

1. **AUX Input** detection may be enabled by toggling the DIP SW 7 *ON*

In this mode:

* **JTAG** functionality is not available
* *Vol-* touch button is available for use with the API


Enable MicroSD Card in 4-wire Mode
""""""""""""""""""""""""""""""""""

+---------+-----------+
|  DIP SW | Position  |
+=========+===========+
|    1    |    ON     |
+---------+-----------+
|    2    |    ON     |
+---------+-----------+
|    3    |    OFF    |
+---------+-----------+
|    4    |    OFF    |
+---------+-----------+
|    5    |    OFF    |
+---------+-----------+
|    6    |    OFF    |
+---------+-----------+
|    7    |    OFF    |
+---------+-----------+
|    8    |    n/a    |
+---------+-----------+

In this mode:

* **JTAG** functionality is not available
* *Vol-* touch button is not available for use with the API
* **AUX Input** detection from the API is not available


Enable JTAG
"""""""""""

+---------+-----------+
|  DIP SW | Position  |
+=========+===========+
|    1    |    OFF    |
+---------+-----------+
|    2    |    OFF    |
+---------+-----------+
|    3    |    ON     |
+---------+-----------+
|    4    |    ON     |
+---------+-----------+
|    5    |    ON     |
+---------+-----------+
|    6    |    ON     |
+---------+-----------+
|    7    |    ON     |
+---------+-----------+
|    8    |    n/a    |
+---------+-----------+

In this mode:

* **MicroSD Card** functionality is not available, remove the card from the slot
* *Vol-* touch button is not available for use with the API
* **AUX Input** detection from the API is not available


Allocation of ESP32 Pins
^^^^^^^^^^^^^^^^^^^^^^^^

Several pins / terminals of ESP32 modules are allocated to the on board hardware. Some of them, like GPIO0 or GPIO2, have multiple functions. Please refer to the tables below or `ESP32 LyraT V4.2 schematic`_ for specific details.


.. _get-started-esp32-lyrat-v4.2-red-green-led:

Red / Green LEDs
""""""""""""""""

+---+-----------+-----------+
|   | ESP32 Pin | LED Color |
+===+===========+===========+
| 1 | GPIO19    | Red LED   |
+---+-----------+-----------+
| 2 | GPIO22    | Green LED |
+---+-----------+-----------+

.. _get-started-esp32-lyrat-v4.2-touch-pads:

Touch Pads
""""""""""

+---+-----------+--------------------+
|   | ESP32 Pin | Touch Pad Function |
+===+===========+====================+
| 1 | GPIO33    | Play               |
+---+-----------+--------------------+
| 2 | GPIO32    | Set                |
+---+-----------+--------------------+
| 3 | GPIO13    | Vol- :sup:`1`      |
+---+-----------+--------------------+
| 4 | GPIO27    | Vol+               |
+---+-----------+--------------------+

1. *Vol-* function is not available if **JTAG** is used. It is also not available for the **MicroSD Card** configured to operate in 4-wire mode.

.. _get-started-esp32-lyrat-v4.2-microsd-card-slot:

MicroSD Card / J5
"""""""""""""""""

+---+---------------+----------------+
|   | ESP32 Pin     | MicroSD Signal |
+===+===============+================+
| 1 | MTDI / GPIO12 | DATA2          |
+---+---------------+----------------+
| 2 | MTCK / GPIO13 | CD / DATA3     |
+---+---------------+----------------+
| 3 | MTDO / GPIO15 | CMD            |
+---+---------------+----------------+
| 4 | MTMS / GPIO14 | CLK            |
+---+---------------+----------------+
| 5 | GPIO2         | DATA0          |
+---+---------------+----------------+
| 6 | GPIO4         | DATA1          |
+---+---------------+----------------+
| 7 | GPIO21        | CD             |
+---+---------------+----------------+

.. note:

    **MicroSD Card** cannot be used if **JTAG** is enabled.


UART Header / JP2
"""""""""""""""""

+---+-------------+
|   | Header Pin  |
+===+=============+
| 1 | 3.3V        |
+---+-------------+
| 2 | TX          |
+---+-------------+
| 3 | RX          |
+---+-------------+
| 4 | GND         |
+---+-------------+


EN and IO0 Headers / JP23 and J24
"""""""""""""""""""""""""""""""""
+---+-------------+-------------+
|   | ESP32 Pin   | Header Pin  |
+===+=============+=============+
| 1 | n/a         | EN_Auto     |
+---+-------------+-------------+
| 2 | EN          | EN          |
+---+-------------+-------------+

+---+-------------+-------------+
|   | ESP32 Pin   | Header Pin  |
+===+=============+=============+
| 1 | n/a         | IO0_Auto    |
+---+-------------+-------------+
| 2 | GPIO0       | IO0         |
+---+-------------+-------------+


.. _get-started-esp32-lyrat-v4.2-i2s-header:

I2S Header / JP4
""""""""""""""""

+---+----------------+-------------+
|   | I2C Header Pin | ESP32 Pin   |
+===+================+=============+
| 1 | MCLK           | GPI0        |
+---+----------------+-------------+
| 2 | SCLK           | GPIO5       |
+---+----------------+-------------+
| 1 | LRCK           | GPIO25      |
+---+----------------+-------------+
| 2 | DSDIN          | GPIO26      |
+---+----------------+-------------+
| 3 | ASDOUT         | GPIO35      |
+---+----------------+-------------+
| 3 | GND            | GND         |
+---+----------------+-------------+

.. _get-started-esp32-lyrat-v4.2-i2c-header:

I2C Header / JP5
""""""""""""""""

+---+----------------+-------------+
|   | I2C Header Pin | ESP32 Pin   |
+===+================+=============+
| 1 | SCL            | GPIO23      |
+---+----------------+-------------+
| 2 | SDA            | GPIO18      |
+---+----------------+-------------+
| 3 | GND            | GND         |
+---+----------------+-------------+


.. _get-started-esp32-lyrat-v4.2-jtag-header:

JTAG Header / JP7
"""""""""""""""""

+---+---------------+-------------+
|   | ESP32 Pin     | JTAG Signal |
+===+===============+=============+
| 1 | MTDO / GPIO15 | TDO         |
+---+---------------+-------------+
| 2 | MTCK / GPIO13 | TCK         |
+---+---------------+-------------+
| 3 | MTDI / GPIO12 | TDI         |
+---+---------------+-------------+
| 4 | MTMS / GPIO14 | TMS         |
+---+---------------+-------------+

.. note:

    **JTAG** cannot be used if **MicroSD Card** is enabled.


Function DIP Switch / JP8
"""""""""""""""""""""""""

+---+----------------------+-------------------------+
|   | Switch OFF           | Switch ON               |
+===+======================+=========================+
| 1 | GPIO12 not allocated | MicroSD Card 4-wire     |
+---+----------------------+-------------------------+
| 2 | Touch *Vol-* enabled | MicroSD Card 4-wire     |
+---+----------------------+-------------------------+
| 3 | MicroSD Card         | JTAG                    |
+---+----------------------+-------------------------+
| 4 | MicroSD Card         | JTAG                    |
+---+----------------------+-------------------------+
| 5 | MicroSD Card         | JTAG                    |
+---+----------------------+-------------------------+
| 6 | MicroSD Card         | JTAG                    |
+---+----------------------+-------------------------+
| 7 | MicroSD Card 4-wire  | AUX IN detect :sup:`1`  |
+---+----------------------+-------------------------+
| 8 | not used             | not used                |
+---+----------------------+-------------------------+

1.  The **AUX Input** signal pin should not be be plugged in when the system powers up. Otherwise the ESP32 may not be able to boot correctly.


.. _get-started-esp32-lyrat-v4.2-start-development:

Start Application Development
-----------------------------

Before powering up the ESP32-LyraT, please make sure that the board has been received in good condition with no obvious signs of damage.


Initial Setup
^^^^^^^^^^^^^

Prepare the board for loading of the first sample application:

1. Install jumpers on **IO0** and **EN** headers to enable automatic application upload. If there are no jumpers then upload may be triggered using **Boot** / **RST** buttons.
2. Connect 4-ohm speakers to the **Right** and **Left Speaker Output**.Connecting headphones to the **Headphone Output** is an option.
3. Plug in the Micro-USB cables to the PC and to **both USB ports** of the ESP32 LyraT.
4. The **Standby LED** (green) should turn on.  Assuming that a battery is not connected, the **Charging LED** will blink every couple of seconds.
5. Toggle left the **Power On Switch**.
6. The red **Power On LED** should turn on.

If this is what you see on the LEDs, the board should be ready for application upload. Now prepare the PC by loading and configuring development tools what is discussed in the next section.


Develop Applications
^^^^^^^^^^^^^^^^^^^^

If the ESP32 LyraT is initially set up and checked, you can proceed with preparation of the development tools. Go to section :doc:`index`, which will walk you through the following steps:

* :ref:`get-started-setup-esp-idf` in your PC that provides a common framework to develop applications for the ESP32 in C language;
* :ref:`get-started-get-esp-adf` to have the API specific for the audio applications;
* :ref:`get-started-setup-path` to make the framework aware of the audio specific API;
* :ref:`get-started-start-project` that will provide a sample audio application for the ESP32-LyraT board;
* :ref:`get-started-connect-configure` to prepare the application for loading;
* :ref:`get-started-build-flash-monitor` this will finally run the application and play some music.


Related Documents
-----------------

* `ESP32 LyraT V4.2 schematic`_ (PDF)
* `ESP32 Datasheet <https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf>`_ (PDF)
* `ESP32-WROVER Datasheet <https://espressif.com/sites/default/files/documentation/esp32-wrover_datasheet_en.pdf>`_ (PDF)
* `JTAG Debugging <https://esp-idf.readthedocs.io/en/latest/api-guides/jtag-debugging/index.html>`_
* :doc:`get-started-esp32-lyrat-v4`

.. _ESP32 LyraT V4.2 schematic: https://dl.espressif.com/dl/schematics/esp32-lyrat-v4.2-schematic.pdf
