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What is this?

Squeezelite-esp32 is an audio software suite made to run on espressif's ESP32 wifi (b/g/n) and bluetooth chipset. It offers the following capabilities

  • Stream your local music and connect to all major on-line music providers (Spotify, Deezer, Tidal, Qobuz) using Logitech Media Server - a.k.a LMS and enjoy multi-room audio synchronization. LMS can be extended by numerous plugins and can be controlled using a Web browser or dedicated applications (iPhone, Android). It can also send audio to UPnP, Sonos, ChromeCast and AirPlay speakers/devices.
  • Stream from a Bluetooth device (iPhone, Android)
  • Stream from an AirPlay controller (iPhone, iTunes ...) and enjoy synchronization multiroom as well (although it's AirPlay 1 only)
  • Stream from a Spotify controller

Depending on the hardware connected to the ESP32, you can send audio to a local DAC, to SPDIF or to a Bluetooth speaker. The bare minimum required hardware is a WROVER module with 4MB of Flash and 4MB of PSRAM ( With that module standalone, just apply power and you can stream to a Bluetooth speaker. You can also send audio to most I2S DAC as well as to SPDIF receivers using just a cable or an optical transducer.

Note that streaming to a Bluetooth speaker is not the main purpose and remains experimental, so your mileage will vary. We will not work on improving or fixing that feature, please don't open issues about that.

But squeezelite-esp32 is highly extensible and you can add

  • Buttons and Rotary Encoder and map/combine them to various functions (play, pause, volume, next ...)
  • GPIO expander (buttons, led and rotary)
  • IR receiver (no pullup resistor or capacitor needed, just the 38kHz receiver)
  • Monochrome, GrayScale or Color displays using SPI or I2C (supported drivers are SH1106, SSD1306, SSD1322, SSD1326/7, SSD1351, ST7735, ST7789 and ILI9341).
  • Ethernet using a Microchip LAN8720 with RMII interface or Davicom DM9051/W5500 over SPI.

Other features include

  • Resampling
  • 10-bands equalizer
  • Automatic initial setup using any WiFi device
  • Full web interface for further configuration/management
  • Firmware over-the-air update

To control the equalizer or use the display on LMS, a new player model is required and this is provided through a plugin that is part of LMS' 3rd party repositories


(opinions presented here so I = @philippe44) The main build of squeezelite-esp32 is a 16 bits internal core with all calculations in 32 bits or float precision. This is a design choice I've made to preserve CPU performances (it is already stretching a lot the esp32 chipset) and optimize memory usage as we only have 4MB of usable RAM. Some might correctly comment that the WROVER module have 8MB of RAM, but the processor is only able to address 4MB and the remaining 4MB must be paginated by smaller blocks and I don't have patience to that.

Now, when I did the porting of squeezelite to esp32, I've also made the core 16 or 32 bits compatible at compile-time. So far, it works in 32 bits but less tests have been done. You can chose to compile it in 32 bits mode. I'm not very interested above 16 bits samples because it does not bring anything (I have an engineering background in theory of information).

Capability 16 bits 32 bits comment
max sampling rate 192k 96k 192k is very challenging, especially when combined with display
max bit depth 16 24 24 bits are truncated in 16 bits mode
spdif 16 bits 20 bits
mp3, aac, opus, ogg/vorbis 48k 48k
alac, flac, ogg/flac 96k 96k
pcm, wav, aif 192k 96k
equalizer Y N 48kHz max (after resampling) - equalization skipped on >48k tracks
resampling Y N
cross-fade 10s <5s depends on buffer size and sampling rate

The esp32 must run at 240 MHz, with Quad-SPI I/O at 80 MHz and a clock of 40 Mhz. Still, it's a lot to run, especially knowing that it has a serial Flash and PSRAM, so kudos to Espressif for their chipset optimization. Now, to have all the decoding, resampling, equalizing, gain, display, spectrum/vu is a very (very) delicate equilibrium between use of internal /external RAM, tasks priorities and buffer handling. It is not perfect and the more you push the system to the limit, the higher the risk that some files would not play (see below). In general, the display will always have the lowest priority and you'll notice slowdown in scrolling and VU/Spectrum refresh rates. Now, even display thread has some critical section and impacts the capabilities. For example, a 16 bits-depth color display with low SPI speed might prevent 24/96 flac to work but still work with pcm 24/96

In 16 bits mode, although 192 kHz is reported as max rate, it's highly recommended to limit reported sampling rate to 96k (-Z 96000). Note that some high-speed 24/96k on-line streams might stutter because of TCP/IP stack performances. It is usually due to the fact that the server sends small packets of data and the esp32 cannot receive encoded audio fast enough, regardless of task priority settings (I've tried to tweak that a fair bit). The best option in that case is to let LMS proxy the stream as it will provide larger chunks and a "smoother" stream that can then be handled.

Note as well that some codecs consume more CPU than others or have not been optimized as much. I've done my best to tweak these, but that level of optimization includes writing some assembly which is painful. One very demanding codec is AAC when files are encoded with SBR. It allows reconstruction of upper part of spectrum and thus higher sampling rate, but the codec spec is such that this is optional, you can decode simply lower band and accept lower sampling rate - See the AAC_DISABLE_SBR option below.


To get started, you'll need to perform an initial flash on one of the supported devices (see below) using a usb cable or a serial adapter, depending if your device came with one or if it didn't. The easiest way is to use the esp-web-tool based installer, which is kept up to date with the latest builds we do. After you've completed this step, all subsequent updates will be done from our built-in web interface.

Supported Hardware

Any esp32-based hardware with at least 4MB of flash and 4MB of PSRAM will be capable of running squeezelite-esp32 and there are various boards that include such chip. A few are mentionned below, but any should work. You can find various help & instructions here

For the sake of clarity, WROOM modules DO NOT work as they don't include PSRAM. Some designs might add it externally, but it's (very) unlikely.

Raw WROVER module

Per above description, a WROVER module is enough to run Squeezelite-esp32, but that requires a bit of tinkering to extend it to have analogue audio or hardware buttons (e.g.)

Please note that when sending to a Bluetooth speaker (source), only 44.1 kHz can be used, so you either let LMS do the resampling, but you must make sure it only sends 44.1kHz tracks or enable internal resampling (using -R) option. If you connect a DAC, choice of sample rates will depends on its capabilities. See below for more details.

Most DAC will work out-of-the-box with simply an I2S connection, but some require specific commands to be sent using I2C. See DAC option below to understand how to send these dedicated commands. There is build-in support for TAS575x, TAS5780, TAS5713 and AC101 DAC.


This is the main hardware companion of Squeezelite-esp32 and has been developped together. Details on capabilities can be found here and here.

If you want to rebuild, use the squeezelite-esp32-SqueezeAmp-sdkconfig.defaults configuration file.

NB: You can use the pre-build binaries SqueezeAMP4MBFlash which has all the hardware I/O set properly. You can also use the generic binary I2S4MBFlash in which case the NVS parameters shall be set to get the exact same behavior

  • set_GPIO: 12=green,13=red,34=jack,2=spkfault
  • bat_config: channel=7,scale=20.24
  • dac_config: model=TAS57xx,bck=33,ws=25,do=32,sda=27,scl=26,mute=14:0
  • spdif_config: bck=33,ws=25,do=15


This portable battery-powered speaker is compatible with squeezelite-esp32 for which there is a dedicated build supplied with every update. If you want to rebuild, use the squeezelite-esp32-Muse-sdkconfig.defaults configuration file.

NB: You can use the pre-build binaries Muse4MBFlash which has all the hardware I/O set properly. You can also use the generic binary I2S4MBFlash in which case the NVS parameters shall be set to get the exact same behavior

  • target: muse
  • bat_config: channel=5,scale=7.48,atten=3,cells=1
  • spi_config: "mosi=15,miso=2,clk=14 (this one is probably optional)
  • dac_config: model=I2S,bck=5,ws=25,do=26,di=35,i2c=16,sda=18,scl=23,mck
  • dac_controlset: {"init":[ {"reg":0,"val":128}, {"reg":0,"val":0}, {"reg":25,"val":4}, {"reg":1,"val":80}, {"reg":2,"val":0}, {"reg":8,"val":0}, {"reg":4,"val":192}, {"reg":0,"val":18}, {"reg":1,"val":0}, {"reg":23,"val":24}, {"reg":24,"val":2}, {"reg":38,"val":9}, {"reg":39,"val":144}, {"reg":42,"val":144}, {"reg":43,"val":128}, {"reg":45,"val":128}, {"reg":27,"val":0}, {"reg":26,"val":0}, {"reg":2,"val":240}, {"reg":2,"val":0}, {"reg":29,"val":28}, {"reg":4,"val":48}, {"reg":25,"val":0}, {"reg":46,"val":33}, {"reg":47,"val":33} ]}
  • actrls_config: buttons
  • define a "buttons" variable with: [{"gpio":32, "pull":true, "debounce":10, "normal":{"pressed":"ACTRLS_VOLDOWN"}}, {"gpio":19, "pull":true, "debounce":40, "normal":{"pressed":"ACTRLS_VOLUP"}}, {"gpio":12, "pull":true, "debounce":40, "long_press":1000, "normal":{"pressed":"ACTRLS_TOGGLE"},"longpress":{"pressed":"ACTRLS_POWER"}}]


Works with ESP32-A1S module that includes audio codec and headset output. You still need to use a demo board like this or an external amplifier if you want direct speaker connection. Note that there is a version with AC101 codec and another one with ES8388 with probably two variants - these boards are a mess (see below)

The board shown above has the following IO set

  • amplifier: GPIO21
  • key2: GPIO13, key3: GPIO19, key4: GPIO23, key5: GPIO18, key6: GPIO5 (to be confirmed with dip switches)
  • key1: not sure, using GPIO36 in a matrix
  • jack insertion: GPIO39 (inserted low)
  • D4 -> GPIO22 used for green LED (active low)
  • D5 -> GPIO19 (muxed with key3)
  • The IO connector also brings GPIO5, GPIO18, GPIO19, GPIO21, GPIO22 and GPIO23 (don't forget it's muxed with keys!)
  • The JTAG connector uses GPIO 12, 13, 14 and 15 (see dip switch) but these are also used for SD-card (and GPIO13 is key2 as well)
  • It's always possible to re-use GPIOO (download at boot) and GPIO1/GPIO3 which are RX/TX of UART0 but you'll lose trace

(note that some GPIO need pullups)

So a possible config would be

  • set_GPIO: 21=amp,22=green:0,39=jack:0
  • a button mapping:
     [{"gpio":5,"normal":{"pressed":"ACTRLS_TOGGLE"}},{"gpio":18,"pull":true,"shifter_gpio":5,"normal":{"pressed":"ACTRLS_VOLUP"}, "shifted":{"pressed":"ACTRLS_NEXT"}}, {"gpio":23,"pull":true,"shifter_gpio":5,"normal":{"pressed":"ACTRLS_VOLDOWN"},"shifted":{"pressed":"ACTRLS_PREV"}}]

for AC101

  • dac_config: model=AC101,bck=27,ws=26,do=25,di=35,sda=33,scl=32

for ES8388 (it seems that there are variants with same version number - a total mess)

  • dac_config: model=ES8388,bck=5,ws=25,do=26,sda=18,scl=23,i2c=16 or
  • dac_config: model=ES8388,bck=27,ws=25,do=26,sda=33,scl=32,i2c=16

T-WATCH2020 by LilyGo

This is a fun smartwatch based on ESP32. It has a 240x240 ST7789 screen and onboard audio. Not very useful to listen to anything but it works. This is an example of a device that requires an I2C set of commands for its dac (see below). There is a build-option if you decide to rebuild everything by yourself, otherwise the I2S default option works with the following parameters

  • dac_config: model=I2S,bck=26,ws=25,do=33,i2c=106,sda=21,scl=22
  • dac_controlset:
     { "init": [ {"reg":41, "val":128}, {"reg":18, "val":255} ], "poweron": [ {"reg":18, "val":64, "mode":"or"} ], "poweroff": [ {"reg":18, "val":191, "mode":"and"} ] }
  • spi_config: dc=27,data=19,clk=18
  • display_config: SPI,driver=ST7789,width=240,height=240,cs=5,back=12,speed=16000000,HFlip,VFlip


Squeezelite-esp32 requires esp32 chipset and 4MB PSRAM. ESP32-WROVER meets these requirements. To get an audio output an I2S DAC can be used. Cheap PCM5102 I2S DACs work others may also work. PCM5012 DACs can be hooked up via:

VCC - 3.3V
3.3V - 3.3V
BCK - (BCK - see below)
DIN - (DO - see below)
LCK - (WS - see below) FMT - GND
XMT - 3.3V

Use the squeezelite-esp32-I2S-4MFlash-sdkconfig.defaults configuration file.

SqueezeAmpToo !

And the super cool project


To access NVS, in the webUI, go to credits and select "shows nvs editor". Go into the NVS editor tab to change NFS parameters. In syntax description below <> means a value while [] describe optional parameters.

As mentionned above, there are a few dedicated builds that are provided today: SqueezeAMP and Muse but if you build it yourself, you can also create a build for T-WATCH2020. The default build is a generic firmware named I2S which can be configured through NVS to produce exactly the same results than dedicated builds. The difference is that parameters must be entered and can accidently be erased. The GUI provides a great help to load "known config sets" as well.

By design choice, there is no code that is only embedded for a given version, all code is always there. The philosophy is to minimize as much as possible platform-specific code and use of specific #ifdef is prohibited, no matter what. So if you want to add your own platfrom, please look very hard at the main\KConfig.projbuild to see how you can, using parameters below, make your device purely a configuration-based solution. When there is really no other option, look at targets\<target> to add your own code. I will not accept PR for code that can avoid creating such dedicated code whenever possible. The NVS "target" will be used to call target-specific code then, but again this is purely runtime, not compile-time.


The NVS parameter "i2c_config" set the i2c's gpio used for generic purpose (e.g. display). Leave it blank to disable I2C usage. Note that on SqueezeAMP, port must be 1. Default speed is 400000 but some display can do up to 800000 or more. Syntax is


Please note that you can not use the same GPIO or port as the DAC.


The esp32 has 3 user-accessible SPI sub-systems but SPI0 and SPI2 are reserved for internal use and Flash/PSRAM, so only SPI1 is available. The NVS parameter "spi_config" set the spi's gpio used for user purpose (e.g. display, ethernet, GPIO expander). Leave it blank to disable SPI usage. The DC parameter is needed for displays. Syntax is


Default and only "host" is 1 as others are used already by flash and spiram. The optional "miso" (MasterInSlaveOut) parameter is only used when SPI bus is bi-directional and shared with other peripheral like ethernet, gpio expander. Note that "data" can also be named "mosi" (MasterOutSlaveIn).


The NVS parameter "dac_config" set the gpio used for i2s communication with your DAC. You can define the defaults at compile time but nvs parameter takes precedence except for SqueezeAMP and A1S where these are forced at runtime. Syntax is


if "model" is not set or is not recognized, then default "I2S" is used. The option "mck" is used for some codecs that require a master clock (although they should not). Only GPIO0 can be used as MCLK and be aware that this cannot coexit with RMII Ethernet (see ethernet section below). I2C parameters are optional and only needed if your DAC requires an I2C control (See 'dac_controlset' below). Note that "i2c" parameters are decimal, hex notation is not allowed.

So far, TAS57xx, TAS5713, AC101, WM8978 and ES8388 are recognized models where the proper init sequence/volume/power controls are sent. For other codecs that might require an I2C commands, please use the parameter "dac_controlset" that allows definition of simple commands to be sent over i2c for init, power, speakder and headset on and off using a JSON syntax:

{ <command>: [ {"reg":<register>,"val":<value>,"mode":<nothing>|"or"|"and"}, ... {{"reg":<register>,"val":<value>,"mode":<nothing>|"or"|"and"} ],
  <command>: [ {"reg":<register>,"val":<value>,"mode":<nothing>|"or"|"and"}, ... {{"reg":<register>,"val":<value>,"mode":<nothing>|"or"|"and"} ],
  ... }

Where <command> is one of init, poweron, poweroff, speakeron, speakeroff, headseton, headsetoff

This is standard JSON notation, so if you are not familiar with it, Google is your best friend. Be aware that the '...' means you can have as many entries as you want, it's not part of the syntax. Every section is optional, but it does not make sense to set i2c in the 'dac_config' parameter and not setting anything here. The parameter 'mode' allows to or the register with the value or to and it. Don't set 'mode' if you simply want to write. The 'val parameter can be an array [v1, v2,...] to write a serie of bytes in a single i2c burst (in that case 'mode' is ignored). Note that all values must be decimal. You can use a validator like this to verify your syntax

NB: For specific builds (all except I2S), all this is ignored. For know codecs, the built-in sequences can be overwritten using dac_controlset

Please note that you can not use the same GPIO or port as the I2C.


The NVS parameter "spdif_config" sets the i2s's gpio needed for SPDIF.

SPDIF is made available by re-using i2s interface in a non-standard way, so although only one pin (DO) is needed, the controller must be fully initialized, so the bit clock (bck) and word clock (ws) must be set as well. As i2s and SPDIF are mutually exclusive, you can reuse the same IO if your hardware allows so.

You can define the defaults at compile time but nvs parameter takes precedence except for SqueezeAMP where these are forced at runtime.

Leave it blank to disable SPDIF usage, you can also define them at compile time using "make menuconfig". Syntax is


NB: For well-known configuration, this is ignored

To optimize speed, a bit-manipulation trick is used and as a result, the bit depth is limited to 20 bits, even in 32 bits mode. As said before, this is more than enough for any human ear. In theory, it could be extended up to 23 bits but I don't see the need. Now, you can also get SPDIF using a specialized chip that offers a I2S interface like a DAC but spits out SPDIF (optical and coax). Refers to DAC chapter then.

If you want coax, you can also use a poor-man's trick to generate signal from a 3.3V GPIO. All that does is dividing the 3.3V to generate a 0.6V peak-to-peak and then remove DC

GPIO  ----210ohm-----------||---- coax S/PDIF signal out
Ground -------------------------- coax signal ground


The NVS parameter "display_config" sets the parameters for an optional display. It can be I2C (see here for shared bus) or SPI (see here for shared bus) Syntax is

  • back: a LED backlight used by some older devices (ST7735). It is PWM controlled for brightness
  • reset: some display have a reset pin that is should normally be pulled up if unused. Most displays require reset and will not initialize well otherwise.
  • VFlip and HFlip are optional can be used to change display orientation
  • rotate: for non-square drivers, move to portrait mode. Note that width and height must be inverted then
  • invert: pixel invertion
  • cswap: some display require a GBR color ordering instead of RGB (ST77xx only)
  • Default speed is 8000000 (8MHz) but SPI can work up to 26MHz or even 40MHz
  • SH1106 is 128x64 monochrome I2C/SPI here
  • SSD1306 is 128x32 monochrome I2C/SPI here
  • SSD1322 is 256x64 grayscale 16-levels SPI in multiple sizes here - it is very nice
  • SSD1326 is 256x32 monochrome or grayscale 16-levels SPI here
  • SSD1327 is 128x128 16-level grayscale SPI here - artwork can be up to 96x96 with vertical vu-meter/spectrum
  • SSD1351 is 128x128 65k/262k color SPI here
  • SSD1675 is an e-ink paper and is experimental as e-ink is really not suitable for LMS du to its very low refresh rate
  • ST7735 is a 128x160 65k color SPI here. This needs a backlight control. Some have X/Y offsets betwen the driver and the glass (green/black/red models) that can be added using "x" and "y" options (case sensitive!)
  • ST7789 is a 240x320 65k (262k not enabled) color SPI here. It also exist with 240x240 displays. See rotate for use in portrait mode
  • ILI9341 is another 240x320 65k (262k capable) color SPI. I've not used it much, the driver it has been provided by one external contributor to the project

You can tweak how the vu-meter and spectrum analyzer are displayed, as well as size of artwork through a dedicated menu in player's settings (don't forget to add the plugin).

The NVS parameter "metadata_config" sets how metadata is displayed for AirPlay and Bluetooth. Syntax is

  • 'speed' is the scrolling speed in ms (default is 33ms)
  • 'pause' is the pause time between scrolls in ms (default is 3600ms)
  • 'format' can contain free text and any of the 3 keywords %artist%, %album%, %title%. Using that format string, the keywords are replaced by their value to build the string to be displayed. Note that the plain text following a keyword that happens to be empty during playback of a track will be removed. For example, if you have set format=%artist% - %title% and there is no artist in the metadata then only <title> will be displayed not - <title>.
  • 'artwork' enables coverart display, if available (does not work for Bluetooth). The optional parameter indicates if the artwork should be resized (1) to fit the available space. Note that the built-in resizer can only do 2,4 and 8 downsizing, so fit is not optimal. The artwork will be placed at the right of the display for landscape displays and underneath the two information lines for others (there is no user option to tweak that).


You can use any IR receiver compatible with NEC protocol (38KHz). Vcc, GND and output are the only pins that need to be connected, no pullup, no filtering capacitor, it's a straight connection.

The IR codes are send "as is" to LMS, so only a Logitech SB remote from Boom, Classic or Touch will work. I think the file in the "server" directory of LMS can be modified to adapt to other codes, but I've not tried that.

In AirPlay and Bluetooth mode, only these native remotes are supported, I've not added the option to make your own mapping

See "set GPIO" below to set the GPIO associated to infrared receiver (option "ir").


The parameter "set_GPIO" is used to assign GPIO to various functions.

GPIO can be set to GND provide or Vcc at boot. This is convenient to power devices that consume less than 40mA from the side connector. Be careful because there is no conflict checks being made wrt which GPIO you're changing, so you might damage your board or create a conflict here.

The <amp> parameter can use used to assign a GPIO that will be set to active level (default 1) when playback starts. It will be reset when squeezelite becomes idle. The idle timeout is set on the squeezelite command line through -C <timeout>

If you have an audio jack that supports insertion (use :0 or :1 to set the level when inserted), you can specify which GPIO it's connected to. Using the parameter jack_mutes_amp allows to mute the amp when headset (e.g.) is inserted.

You can set the Green and Red status led as well with their respective active state (:0 or :1)

The <ir> parameter set the GPIO associated to an IR receiver. No need to add pullup or capacitor

Syntax is:

<gpio>=Vcc|GND|amp[:1|0]|ir|jack[:0|1]|green[:0|1]|red[:0|1]|spkfault[:0|1][,<repeated sequence for next GPIO>]

You can define the defaults for jack, spkfault leds at compile time but nvs parameter takes precedence except for well-known configurations where these are forced at runtime. Note that gpio 36 and 39 are input only and cannot use interrupt. When set to jack or speaker fault, a 100ms polling checks their value but that's expensive

GPIO expanders

It is possible to add GPIO expanders using I2C or SPI bus. They should mainly be used for buttons but they can support generic-purpose outputs as well. These additional GPIOs can be numbered starting from an arbitrary value (40 and above as esp32 has GPIO 0..39). Then these new "virtual" GPIOs from (e.g) 100 to 115 can be used in button configuration, set_GPIO or other config settings.

Each expander can support up to 32 GPIO. To use an expander for buttons, an interrupt must be provided, polling mode is not acceptable. An expander w/o interruption can still be configured, but only output will be usable. Note that the same interrupt can be shared accross expanders, as long as they are using open drain or open collectors (which they probably all do)

The parameter "gpio_exp_config" is a semicolon (;) separated list with following syntax for each expander

  • model: pca9535, pca85xx, mcp23017 and mcp23s17 (SPI version)
  • addr: chip i2c/spi address (decimal)
  • port (I2C): use either "system" port (shared with display for example) or "dac" port (system is default)
  • cs (SPI): gpio used for Chip Select
  • speed (SPI): speed of the SPI bus for that device (in Hz)
  • base: GPIO numbering offset to use everywhere else (default 40)
  • count: number of GPIO of expander (default 16 - might be obsolted if model if sufficient to decide)
  • intr: real GPIO to use as interrupt.

Note that PWM ("led_brightness" below) is not supported for expanded GPIOs and they cannot be used for high speed or precise timing signals like CS, D/C, Reset and Ready. Buttons, rotary encoder, amplifier control and power are supported. Depending on the actual chipset, pullup or pulldown might be supported so you might have to add external resistors (only MCP23x17 does pullup). The pca8575 is not a great chip, it generate a fair bit of spurious interrupts when used for GPIO out. When using a SPI expander, the bus must be configured using shared SPI bus


See set_GPIO for how to set the green and red LEDs. In addition, their brightness can be controlled using the "led_brigthness" parameter. The syntax is


NB: For well-known configuration, this is ignored

Rotary Encoder

One rotary encoder is supported, quadrature shift with press. Such encoders usually have 2 pins for encoders (A and B), and common C that must be set to ground and an optional SW pin for press. A, B and SW must be pulled up, so automatic pull-up is provided by ESP32, but you can add your own resistors. A bit of filtering on A and B (~470nF) helps for debouncing which is not made by software.

Encoder is normally hard-coded to respectively knob left, right and push on LMS and to volume down/up/play toggle on BT and AirPlay. Using the option 'volume' makes it hard-coded to volume down/up/play toggle all the time (even in LMS). The option 'longpress' allows an alternate mode when SW is long-pressed. In that mode, left is previous, right is next and press is toggle. Every long press on SW alternates between modes (the main mode actual behavior depends on 'volume').

There is also the possibility to use 'knobonly' option (exclusive with 'volume' and 'longpress'). This mode attempts to offer a single knob full navigation which is a bit contorded due to LMS UI's principles. Left, Right and Press obey to LMS's navigation rules and especially Press always goes to lower submenu item, even when navigating in the Music Library. That causes a challenge as there is no 'Play', 'Back' or 'Pause' button. Workaround are as of below:

  • longpress is 'Play'
  • double press is 'Back' (Left in LMS's terminology).
  • a quick left-right movement on the encoder is 'Pause'

The speed of double click (or left-right) can be set using the optional parameter of 'knobonly'. This is not a perfect solution, and other ideas are welcome. Be aware that the longer you set double click speed, the less responsive the interface will be. The reason is that I need to wait for that delay before deciding if it's a single or double click. It can also make menu navigation "hesitations" being easily interpreted as 'Pause'

Use parameter rotary_config with the following syntax:


HW note: all gpio used for rotary have internal pull-up so normally there is no need to provide Vcc to the encoder. Nevertheless if the encoder board you're using also has its own pull-up that are stronger than ESP32's ones (which is likely the case), then there will be crosstalk between gpio, so you must bring Vcc. Look at your board schematic and you'll understand that these board pull-up create a "winning" pull-down when any other pin is grounded.

The SW gpio is optional, you can re-affect it to a pure button if you prefer but the volume, longpress and knobonly options make little sense as the missing switch plays an important role in these modes. You could still have the "volume" mode, but you won't be able to use it for anything expect volume up and down. So be aware that the use of syntax [] is a bit misleading hereabove.

See also the "IMPORTANT NOTE" on the "Buttons" section and remember that when 'lms_ctrls_raw' (see below) is activated, none of these knobonly,volume,longpress options apply, raw button codes (not actions) are simply sent to LMS

Note that gpio 36 and 39 are input only and cannot use interrupt, so they cannot be set to A or B. When using them for SW, a 100ms polling is used which is expensive


Buttons are described using a JSON string with the following syntax

 "normal": {"pressed":"<action>","released":"<action>"},
 "longpress": { <same> },
 "shifted": { <same> },
 "longshifted": { <same> },
 { ... },
 { ... },

Where (all parameters are optionals except gpio)

  • "type": (BUTTON_LOW) logic level when the button is pressed
  • "pull": (false) activate internal pull up/down
  • "long_press": (0) duration (in ms) of keypress to detect long press, 0 to disable it
  • "debounce": (0) debouncing duration in ms (0 = internal default of 50 ms)
  • "shifter_gpio": (-1) gpio number of another button that can be pressed together to create a "shift". Set to -1 to disable shifter
  • "normal": ({"pressed":"ACTRLS_NONE","released":"ACTRLS_NONE"}) action to take when a button is pressed/released (see below)
  • "longpress": action to take when a button is long-pressed/released (see above/below)
  • "shifted": action to take when a button is pressed/released and shifted (see above/below)
  • "longshifted": action to take when a button is long-pressed/released and shifted (see above/below)

Where <action> is either the name of another configuration to load (remap) or one amongst


One you've created such a string, use it to fill a new NVS parameter with any name below 16(?) characters. You can have as many of these configs as you can. Then set the config parameter "actrls_config" with the name of your default config

For example a config named "buttons" :

 {"gpio":5,"type":"BUTTON_LOW","pull":true,"shifter_gpio":4,"normal":{"pressed":"ACTRLS_VOLUP"}, "shifted":{"pressed":"ACTRLS_TOGGLE"}}]

Defines two buttons

  • first on GPIO 4, active low. When pressed, it triggers a volume down command. When pressed more than 1000ms, it changes the button configuration for the one named "buttons_remap"
  • second on GPIO 5, active low. When pressed it triggers a volume up command. If first button is pressed together with this button, then a play/pause toggle command is generated.

While the config named "buttons_remap"


Defines two buttons

  • first on GPIO 4, active low. When pressed, it triggers a navigation down command. When pressed more than 1000ms, it changes the button configuration for the one described above
  • second on GPIO 5, active low. When pressed it triggers a navigation up command. That button, in that configuration, has no shift option

Below is a difficult but functional 2-buttons interface for your decoding pleasure:







IMPORTANT NOTE: LMS also supports the possibility to send 'raw' button codes. It's a bit complicated, so bear with me. Buttons can either be processed by SqueezeESP32 and mapped to a "function" like play/pause or they can be just sent to LMS as plain (raw) code and the full logic of press/release/longpress is handled by LMS, you don't have any control on that.

When buttons are mapped to a "function" (non "raw" mode) a command is sent to LMS using the CLI (Command Line Interface) but this only works if LMS does not have a password set. In "raw" mode, a button code is sent using the always-openn control socket between LMS and the player.

The benefit of the "raw" mode is that you can build a player which is as close as possible to a Boom (e.g.) but you can't use the remapping function nor longress or shift logics to do your own mapping when you have a limited set of buttons. In 'raw' mode, all you really need to define is the mapping between the gpio and the button. As far as LMS is concerned, any other option in these JSON payloads does not matter. Now, when you use BT or AirPlay, the full JSON construct described above fully applies, so the shift, longpress, remapping options still work.

There is no good or bad option, it's your choice. Use the NVS parameter "lms_ctrls_raw" to change that option

Note that gpio 36 and 39 are input only and cannot use interrupt. When using them for a button, a 100ms polling is started which is expensive. Long press is also likely to not work very well

Ethernet (required unpublished version 4.3)

Wired ethernet is supported by esp32 with various options but squeezelite is only supporting a Microchip LAN8720 with a RMII interface like this or SPI-ethernet bridges like Davicom DM9051 that or W5500 like this.

Note: Touch buttons that can be find on some board like the LyraT V4.3 are not supported currently.

RMII (LAN8720)

  • RMII PHY wiring is fixed and can not be changed
GPIO RMII Signal Notes
GPIO0 REF_CLK 50MHz clock
  • SMI (Serial Management Interface) wiring is not fixed and you can change it either in the configuration or using "eth_config" parameter with the following syntax:

Connecting a reset pin for the LAN8720 is optional but recommended to avoid that GPIO0 (50MHz input clock) locks the esp32 in download mode at boot time.

  • Clock

The APLL of the esp32 is required for the audio codec, so we need a LAN8720 that provides a 50MHz clock. That clock must be connected to GPIO0, there is no alternative. This means that if your DAC requires an MCLK, then you are out of luck. It is not possible to have both to work together. There might be some workaround using CLK_OUT2 and GPIO3, but I don't have time for this.

SPI (DM9051 or W5500)

Ethernet over SPI is supported as well and requires less GPIOs but is obvsiously slower. SPI is the shared bus set with spi_config. The "eth_config" parameter syntax becomes:

  • The reset pin is optional but recommended
  • The esp32 has a special I/O multiplexer for faster speed (up to 80 MHz) but that requires using specific GPIOs, which depends on SPI bus (See here for more details). Note that currently only SPI2 is available.
Pin Name SPI1 SPI2
CS 15 5
SCLK 14 18
MISO 12 19
MOSI 13 23

Battery / ADC

The NVS parameter "bat_config" sets the ADC1 channel used to measure battery/DC voltage. The "atten" value attenuates the input voltage to the ADC input (the read value maintains a 0-1V rage) where: 0=no attenuation(0..800mV), 1=2.5dB attenuation(0..1.1V), 2=6dB attenuation(0..1.35V), 3=11dB attenuation(0..2.6V). Scale is a float ratio applied to every sample of the 12 bits ADC. A measure is taken every 10s and an average is made every 5 minutes (not a sliding window). Syntax is


NB: Set parameter to empty to disable battery reading. For well-known configuration, this is ignored (except for SqueezeAMP where number of cells is required)


Setup WiFi

  • Boot the esp, look for a new wifi access point showing up and connect to it. Default build ssid and passwords are "squeezelite"/"squeezelite".
  • Once connected, navigate to
  • Wait for the list of access points visible from the device to populate in the web page.
  • Choose an access point and enter any credential as needed
  • Once connection is established, note down the address the device received; this is the address you will use to configure it going forward

Setup squeezelite command line (optional)

At this point, the device should have disabled its built-in access point and should be connected to a known WiFi network.

  • navigate to the address that was noted in step #1
  • Using the list of predefined options, choose the mode in which you want squeezelite to start
  • Generate the command
  • Add or change any additional command line option (for example player name, etc)
  • Activate squeezelite execution: this tells the device to automatiaclly run the command at start
  • Update the configuration
  • click on the "start toggle" button. This will force a reboot.
  • The toggle switch should be set to 'ON' to ensure that squeezelite is active after booting (you might have to fiddle with it a few times)
  • You can enable accessto NVS parameters under 'credits'


In addition of the esp-idf serial link monitor option, you can also enable a telnet server (see NVS parameters) where you'll have access to a ton of logs of what's happening inside the WROVER.

Update Squeezelite

  • From the firmware tab, click on "Check for Updates"
  • Look for updated binaries
  • Select a line
  • Click on "Flash!"
  • The system will reboot into recovery mode (if not already in that mode), wipe the squeezelite partition and download/flash the selected version
  • You can choose a local file or have a local webserver


  • From the firmware tab, click on the "Recovery" button. This will reboot the ESP32 into recovery, where additional configuration options are available from the NVS editor

Additional configuration notes (from the Web UI)

The squeezelite options are very similar to the regular Linux ones. Differences are :

- the output is -o ["BT -n '<sinkname>' "] | [I2S]
- if you've compiled with RESAMPLE option, normal soxr options are available using -R [-u <options>]. Note that anything above LQ or MQ will overload the CPU
- if you've used RESAMPLE16, <options> are (b|l|m)[:i], with b = basic linear interpolation, l = 13 taps, m = 21 taps, i = interpolate filter coefficients

For example, so use a BT speaker named MySpeaker, accept audio up to 192kHz and resample everything to 44100 and use 16 bits resample with medium quality, the command line is:

squeezelite -o "BT -n 'BT <sinkname>'" -b 500:2000 -R -u m -Z 192000 -r "44100-44100"

See squeezlite command line, but keys options are

- Z <rate> : tell LMS what is the max sample rate supported before LMS resamples
- R (see above)
- r "<minrate>-<maxrate>"
- C <sec> : set timeout to switch off amp gpio
- W : activate WAV and AIFF header parsing

Building everything yourself

Setting up ESP-IDF


You can use docker to build squeezelite-esp32 (optional) First you need to build the Docker container:

docker build -t esp-idf .

Then you need to run the container:

docker run -i -t -v `pwd`:/workspace/squeezelite-esp32 esp-idf

The above command will mount this repo into the docker container and start a bash terminal for you to then follow the below build steps

Manual Install of ESP-IDF

You can install IDF manually on Linux or Windows (using the Subsystem for Linux) following the instructions at: or see here for a direct install.

Use the esp-idf 4.0 and a recent add esp-dsp (after 08/2020)

Building Squeezelite-esp32

When initially cloning the repo, make sure you do it recursively. For example: git clone --recursive

Don't forget to choose one of the config files in build_scripts/ and rename it sdkconfig.defaults or sdkconfig as many important WiFi/BT options are set there. The codecs libraries will not be rebuilt by these scripts (it's a tedious process - see below)

Create and tweak your config using menuconfig then build binaries using all. It will build the recovery and the application (squeezelite). then use flash to write everything. Otherwise, if you just want to download squeezelite, do (assuming you have set ESPPORT (e.g. COM10) and ESPBAUD (e.g. 921600)

<path_to_your_python>/python.exe <path_to_your_esptool>/ -p %ESPPORT% -b %ESPBAUD% --before default_reset --after hard_reset write_flash --flash_mode dio --flash_size detect --flash_freq 80m 0x150000 build/squeezelite.bin

Use monitor to monitor the application (see esp-idf documentation)

Note: You can use build -DDEPTH=32 to build the 32 bits version and add the -DVERSION=<your_version> to add a custom version name (it will be 0.0-<your_version>). If you want to change the whole version string, see squeezelite.h. You can also disable the SBR extension of AAC codecs as it consumes a lot of CPU and might overload the esp32. Use -DAAC_DISABLE_SBR=1 for that

If you have already cloned the repository and you are getting compile errors on one of the submodules (e.g. telnet), run the following git command in the root of the repository location: git submodule update --init --recursive

Rebuild codecs (highly recommended to NOT try that)

  • for codecs libraries, add -mlongcalls if you want to rebuild them, but you should not (use the provided ones in codecs/lib). if you really want to rebuild them, open an issue
  • libmad, libflac (no esp's version), libvorbis (tremor - not esp's version), alac work
  • libfaad does not really support real time, but if you want to try (but using helixaac is a better option)
    • change ac_link in configure and case ac_files, remove ''
    • compiler but in cfft.c and cffti1, must disable optimization using #pragma GCC push_options #pragma GCC optimize ("O0") #pragma GCC pop_options
  • opus & opusfile
    • for opus, the ESP-provided library seems to work, but opusfile is still needed
    • per mad & few others, edit configure and change $ac_link to add -c (faking link)
    • change ac_files to remove ''
    • add DEPS_CFLAGS and DEPS_LIBS to avoid pkg-config to be required
    • stack consumption can be very high with some codec variants, so set NONTHREADSAFE_PSEUDOSTACK and GLOBAL_STACK_SIZE=48000 and unset VAR_ARRAYS in config.h
  • libmad has been patched to avoid using a lot of stack and is not provided here. There is an issue with sync detection in 1.15.1b from where the original stack patch was done but since a few fixes have been made wrt sync detection. This 1.15.1b-10 found on debian fixes the issue where mad thinks it has reached sync but has not and so returns a wrong sample rate. It comes at the expense of 8KB (!) of code where a simple check in squeezelite/mad.c that next_frame[0] is 0xff and next_frame[1] & 0xf0 is 0xf0 does the trick ...


(1) SPDIF is made by tricking the I2S bus but this consumes a fair bit of CPU as it multiplies by four the throughput on the i2s bus. To optimize some computation, the parity of the spdif frames must always be 0, so at least one bit has to be available to force it. As SPDIF samples are 20+4 bits length maximum, the LSB is used for that purpose, so the bit 24 is randomly toggling. It does not matter for 16 bits samples but it has been chosen to truncate the last 4 bits for 24 bits samples. I'm sure that some smart dude can further optimize spdif_convert() and use the user bit instead. You're welcome to do a PR but, as said above, I (philippe44) am not interested by 24 bits mental illness :-) and I've already made an effort to provide 20 bits which already way more what's needed :-)


ESP32 Music streaming based on Squeezelite, with support for multi-room sync, AirPlay, Bluetooth, Hardware buttons, display and more






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