Thanks @chegewara

I2C Scan was failing because i2c_master_write does not accept size of 0. This change checks and skips that call if no length is provided (usually when scanning)

ET-Board
No internal LED pin
Missing internal LED pin have been added to this commit.

Fix issue #5506 "WebServer serveStatic () can cause LoadProhibited exception in _svfprintf_r" (#5508)

"Using a Core Debug Level of Verbose and the WebServer serveStatic() function with the default value of nullptr for its cache_header argument, results in a LoadProhibited exception in _svfprintf_r().
This is because serveStatic() calls log_v() with cache_header corresponding to a "%s" in its format but without checking that cache_header is not nullptr, and then logv() (indirectly) calls _svfprintf_r().
On the other hand, with a Core Debug Level other than Verbose, this does not occur."

Changed serveStatic() to the check value of cache_header and if it is nullptr, instead pass an empty string to log_v().

## Summary
https://github.com/espressif/arduino-esp32/pull/5487 introduced a default timeout for WiFiClient, however the default was specified in milliseconds instead of seconds, see https://github.com/espressif/arduino-esp32/commit/be84c8219c251210afd87cac71b8ef3527b601b3#commitcomment-54358731
This 3ms timeout breaks OTA when the processor is busy.

## Impact
Sets the default to a saner value, fixes OTA.

Fixes: https://github.com/espressif/arduino-esp32/issues/5513

Can still race if Serial.begin() is not called in setup()

Fixes: https://github.com/espressif/arduino-esp32/issues/5503

* Add initial support for USB MSC

* Add Firmware Upload/Download With MSC

Current running firmware is available as file inside the MSC Disk. To update the firmware on the ESP, just copy a regular firmware bin into the drive

* Support overwriting of the firmware file

Overwriting a file is done totally differently on MacOS, Windows and Linux. This change supports it on all of them.

* Allow CDC, FirmwareMSC and DFU to be enabled on boot

* Add example ESP32-S2 USB-ONLY board

* Various device code optimizations

Added `end()` methods to MSC classes
Made begin() methods safe to be called multiple times
Optimized CDC class

* Fix CDC Connect/Disconnect detection in Arduino IDE on Windows

* Rework cdc_write

* Update ESP32-S2 board configs

## The problem
WiFiClient's connect method variant where no timeout is passed can block esp32 MCU and may then cause watchdog to kick in and reset the device. This behavior is different from that, what is in arduino-esp8266 core.

## Summary
Some cross-esp libraries (working both on esp32 and 8266), like PubSubClient simply call connect method on WiFiClient, to get connected to remote server. However, connect behavior varies betwen esp arduino 8266 and esp arduino 32 cores. This pull request tries introduce same behavior - to make connect method non-blocking on esp32, like it is with 8266 arduino core.

## Proposed solution
Introduce default fixed timeout that can be changed by #define - by default set to 3 seconds.

### Affected components: 
WiFiClient

### Affected methods:
```c++ 
int connect(IPAddress ip, uint16_t port);
int connect(const char *host, uint16_t port);
```

### Impact
May impact projects or libraries using connect method variant without specified timeout, where:
- remote is located far away or
- connection is heavily limited, or
- remote is slow, when it comes to accept the connection

In [HTTPClient](https://github.com/espressif/arduino-esp32/tree/master/libraries/HTTPClient), if the `Transfer-Encoding` header is set to `identity`, an error (Transfer-Encoding not supported) will occur.

HTTPClient will consider the request as `identity` if the `Transfer-Encoding` header is not set. But it is also defined a response with `identity` explicitly set in the `Transfer-Encoding` header (ref:[MDN Web Docs](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Transfer-Encoding)).

This pull request will allow the request to be processed normally even when `identity` is explicitly set.

Fixes: https://github.com/espressif/arduino-esp32/issues/4842

Fixes: https://github.com/espressif/arduino-esp32/issues/5488

CLASSIC_BT_ENABLED never worked as was incorrectly named, e.g. see
https://github.com/nkolban/esp32-snippets/issues/890#issuecomment-521520934
Now corrected to the update-to-date name CONFIG_BT_CLASSIC_ENABLED.

Fixes: #5375
Fixes: #5050

esp-dsp: master f4d7d6e
esp-face: master 420fc7e
esp-rainmaker: f1b82c7
esp32-camera: master 6a9497b
esp_littlefs: master b58f00c

Adding first version of PULL_REQUEST_TEMPLATE.md.

The purpose of this template is to improve and simplify writing more accurate Release Notes.

Newly compiled esp32-camera driver from https://github.com/espressif/esp32-camera

lwip lib bundled with esp32 Arduino supports only one ntp server. Any additional servers set are just silently ignored.
This default is different from esp8266 Arduino core and very confusing. Most of the examples provided uses 3 different ntp servers for redundancy while only the first one is used actually.
Addressing issue #4964

Fixes: #5429

Closes #5398

Using the same non-blocking socket connect pattern for respecting connection timeout, copied from WiFiClient::connect.

WiFiClient::connect uses lwip_connect_r, whereas start_ssl_client uses lwip_connect. I haven't found what is the difference between them. I tested both, both work ok, so I kept lwip_connect.

- Device will not reset if previous baudrate was not 9600
- CDC Device is not recognized if WebUSB is enabled

* Fix compile archive arguments for the new toolchain

* Add menu to S2 for picking through which port to upload

Internal USB CDC requires to reset and wait for the new port (because persistence is not yet stable)

* USB CDC should also be started in main

* Fix URL and USB version for WebUSB

* Update vendor callback API

* Update CDC::write to use TX_DONE semaphore

* Update USB_Serial example

Links to the new docs updated and new docs build badge added

- add callback function to HTTPUpdate
- update example to print httpupdate progress
- fix ArduinoIDE syntax coloring
Signed-off-by: NJayantajit Gogoi <jayanta.gogoi525@gmail.com>

A typographical error is corrected in the 2nd line of the comment. 
From = " This is un example howto use Touch Intrrerupts "
To = " This is an example of how to use Touch Intrrerupts "

This PR is the initial documentation structure including the basic information about the project and Sphinx configuration.

####CONTENTS:
- Getting Started
- Installing
- Boards
- Libraries
- Library Builder
- Tutorials
- ESP-IDF as Component
- OTA Web Update
- makeEspArduino
- Troubleshooting
- Contributing

This PR also changes the README.md.

Fixes: https://github.com/espressif/arduino-esp32/issues/5376

* Update toolchain

* Update package_esp32_index.template.json

* add optional component dependencies after Kconfig options are known (#5404)

Until this commit, Kconfig options (e.g. CONFIG_TINYUSB_ENABLED) were
used in conditions preceding idf_component_register to determine which
components need to be added to `arduino` component requirements.
However the Kconfig options aren't known at the early expansion stage,
when the component CMakeLists.txt files are expanded the first time
and requirements are evaluated. So all the conditions evaluated as if
the options were not set.
This commit changes the logic to only add these components as
dependencies when the Kconfig options are known. Dependencies become
"weak", which means that if one of the components isn't included into
the build for some reason, it is not added as a dependency.
This may happen, for example, if the component is not present in the
`components` directory or is excluded by setting `COMPONENTS` variable
in the project CMakeLists.txt file.
This also ensures that if the component is not present, it will not be
added as a dependency, and this will allow the build to proceed.

Follow-up to https://github.com/espressif/arduino-esp32/pull/5391.
Closes https://github.com/espressif/arduino-esp32/issues/5319.

* IDF master d93887f9f

* PlatformIO updates for CI (#5387)

* Update PlatformIO CI build script

- Switch to the latest toolchains 8.4.0 for ESP32, ESP32S2, ESP32C3
- Use PlatformIO from master branch for better robustness

* Update package.json for PlatformIO
Co-authored-by: NIvan Grokhotkov <ivan@espressif.com>
Co-authored-by: NValerii Koval <valeros@users.noreply.github.com>

Commit d15e1b0e [1] in the 2.0.0 pull request #4996 introduced a filter
to connect only to WiFi networks with a RSSI of -75 or better. This
results in strage behaviour, as a scan still shows networks, that can't
be connected to, even though with older versions, connecting to those
networks was possible and the connection (albeit slow) was stable.

Remove the RSSI filter for now by setting the threshold to -127, i.e.
the lowest possible value. Maybe in the future the filter threshold
could be exposed to users, to allow filtering out nearly unreachable
networks.

[1] github.com/espressif/arduino-esp32/pull/4996/commits/d15e1b0e

Closes https://github.com/espressif/arduino-esp32/issues/5378

Fixes: #5041

Fixes: https://github.com/espressif/arduino-esp32/issues/5128
Fixes: https://github.com/espressif/arduino-esp32/issues/5324