* Add support to HAL for APB frequencies different than 80MHz

* Add support for CPU frequencies in the IDE board menu

* Switch to fast set_config

* Add method to uart so debug can be reassigned after apb frequency switch

* Return real APB frequency

Experimental!

* ESP-IDF da2116f + esp32-camera f8f26ab +BLE b232e7f

* Fix fail compilation due to missing cpp guard

Add MD5 computation to Esp and add request header with MD5 hash of the running sketch to HTTPUpdate (#2176)

* Fix error in PR #2048: if ::available() is called before ::connect() _rxBuffer is not initialised

* Fixed flash size check and added SPIFFS size check

* Rewriting ESP.getFreeSketchSpace(), moving code from HTTPUpdate.cpp

* Clean warnings when all warning enabled

Not used variables / functions due to debug log

Dual define with different values :
cores\esp32/binary.h
#define B110 6
#define B1000000 64

tools/sdk/include/newlib/sys/termios.h
#define B110        3
#define B1000000   23

Local variable returned in WiFiclient Secure

* change due to deprecated function

* Update with proper variable and label

* Update esp32-hal-i2c.c

* Apply changes requested

* Fix warnings due to #define conflict thanks @atanisoft

wait for FSM to return idle

* Added ESP:: functions for sketch size

* Fixed free space name to match ESP8266

* Added baudrate detection to esp32-hal-uart and HardwareSerial

* Solved compiler warning for uartResizeRxBuffer()

* Add unit to header variable name (timeout_ms)

* Reverting accidentally changed files to master

* Add small delay after baudrate detection

#1869 exposed a resource exhaustion issue. The current HAL layer for I2C support is designed to use a shared interrupt, But, during debugging to solve the interrupt overloading condition identified in #1588, and the generation of pr #1717, the interrupt allocation parameters were changed.  This change was unnecessary, the code will work successfully with shared interrupts.  So, there is no need to assign a private interrupt for each I2C peripheral.

* TX Flow Control and Code cleanup

* Use semaphore instead of delay

TX functionality is done.

* Use single buffer and empty queue on exit

* Fix compile issues because of LwIP code relocation

* Add temporary header to fix Azure not compiling

* Fix AsyncUDP early init

* AsyncUDP Multicast fixes

* Add source mac address and rework multicast

* Allow redefinition of default pins for Serials 1 and 2

* Update IDF to 3276a13

* Update esptool.py to 2.5.0

* Fix sketches

* Fix log level in BluetoothSetial

* rmt driver initial version

* supporting conti mode plus interrupts

* using conitnous mode for sending more data

* working continous mode

* rmt driver cleanup after conti mode

* initial version of rmt driver

* adding a simple example

* adding channel and block locks

* modified of rmt interface for simpler/easier usage

* adding header sentinels, split interface to common and additional settings

* Fixes per code review + support for rx callback mode

* renamed internal structures and enums, fixed formatting

* cmake support for rmt

* refactored tx-conti interrupts to function to make it more readable

* added Tx and Rx examples

* added license headers

* minor updates per review

* used struct access, renamed defines, corrected diagram

* Initial

* Implementation

* Add to CMakelist.txt

* Add example

* Add IRAM_ATTR

fixes #1734

Add functionality allowing rxBuffer of HardwareSerial to be changed in size via HardwareSerial::setRxBufferSize. (#1855)

If the esp32 is reset during a i2c read cycle the slave device may be in control of the SDA line.  

If the SDA line is held low, the esp32 cannot issue a START or STOP to recover the bus. 

The previous code did not correctly configure the SCL output pin, and it cycled SCL 9 times with SDA Low.  Since the slave device was in a READ cycle, it just continued outputting the bits of the current byte.  When the ACK/NAK bit space occurred, The low output value of SDA was interpreted as ACK so the slave device continued with the next byte.  It never terminated the READ cycle. 

This new code will correctly recover from an interrupted READ

* ReSTART fix, Sequencing fix

pr #1665 introduce a problem with ReSTART, when solving this problem I found an interaction between the TxFifo refill, RxFifo empty and CMD[] fill.  during certain sequences a dataqueue command would be skipped, this skipping resulted in a mismatch between the contents of the TxFifo and the i2c command sequence.  The problem manifested as an ACK error. 
In addition to this required bug fix I propose:
* `Wire.begin()` be changed from a `void` to a `bool` this will allow the reset functionality of `Wire.begin()` to be reported.  Currently `Wire.begin()` attempts to reset the i2c Peripheral, but cannot report success/failure.
* `Wire.busy()` be added. this `bool` function returns the hardware status of the bus. This status can be use in multi-master environments for application level interleaving of commands, also in single master environment, it can be used to detect a 'hung' bus.  With the functional change to `Wire.begin()` this allows app level recover of a hung bus.
* `Wire.lastError()` value updated for all errors, previously when interleaving `Wire.endTransmission(false)` and `Wire.readTransmission(false)`, the 128 byte `Wire.write()` buffer was exhausted without generating and error(very exotic). I discovered this error when I created a sequence of directed reads to a EEPROM. Each directed read used 2 bytes of the 128 byte `write()` buffer, so after 64 consecutive ReSTART writes with ReSTART reads, `Wire()`  had no room to record the directed address bytes.  It generated just a NAK check without setting the EEPROMs internal register address.  The succeeding ReSTART read succeeded at incorrect address.
* Changes to the HAL layer:
** added `i2cGetStatus()` which returns the i2c peripheral status word, used to detect bus_busy currently
** added `i2cDebug()` programmatic control of debug buffer output
** changed `i2cAddQueue()` to allow data_only queue element this will allow a i2c transaction to use multiple data pointers.
** removed direct access to DumpInts(), DumpI2c() from app, use i2cDebug() to set trigger points 
 
*

* Update esp32-hal-i2c.c

* Update Wire.cpp

* ReSTART, Sequencing

pr #1665 introduce a problem with ReSTART, when solving this problem I found an interaction between the TxFifo refill, RxFifo empty and CMD[] fill.  during certain sequences a dataqueue command would be skipped, this skipping resulted in a mismatch between the contents of the TxFifo and the i2c command sequence.  The problem manifested as an ACK error. 
In addition to this required bug fix I propose:
* `Wire.begin()` be changed from a `void` to a `bool` this will allow the reset functionality of `Wire.begin()` to be reported.  Currently `Wire.begin()` attempts to reset the i2c Peripheral, but cannot report success/failure.
* `Wire.busy()` be added. this `bool` function returns the hardware status of the bus. This status can be use in multi-master environments for application level interleaving of commands, also in single master environment, it can be used to detect a 'hung' bus.  With the functional change to `Wire.begin()` this allows app level recover of a hung bus.
* `Wire.lastError()` value updated for all errors, previously when interleaving `Wire.endTransmission(false)` and `Wire.readTransmission(false)`, the 128 byte `Wire.write()` buffer was exhausted without generating and error(very exotic). I discovered this error when I created a sequence of directed reads to a EEPROM. Each directed read used 2 bytes of the 128 byte `write()` buffer, so after 64 consecutive ReSTART writes with ReSTART reads, `Wire()`  had no room to record the directed address bytes.  It generated just a NAK check without setting the EEPROMs internal register address.  The succeeding ReSTART read succeeded at incorrect address.
* Changes to the HAL layer:
** added `i2cGetStatus()` which returns the i2c peripheral status word, used to detect bus_busy currently
** added `i2cDebug()` programmatic control of debug buffer output
** changed `i2cAddQueue()` to allow data_only queue element this will allow a i2c transaction to use multiple data pointers.
** removed direct access to DumpInts(), DumpI2c() from app, use i2cDebug() to set trigger points 
 
*

* Forgot DebugFlags Return

@andriyadi found this, total brain fade on my part.

This version no longer needs an interrupt for each byte transferred. It only needs interrupts for START, STOP, FIFO empty/Full or error conditions.  This dramatically reduces the interrupt overhead.  I think the prior version was causing an interrupt overload condition where the ISR was not able to process every interrupt as they happened.

the 'eject' ERROR is and indication of an interrupt triggering without an source.  I am working to eliminate these serviceable interrupt.  This update increase stability on a HelTek Wifi Lora 32 board. with a SSD1306 OLED.  This update fixes a glaring error in the interrupt allocation code, the Interrupt mask was wrong.  I also dynamically adjust the FiFo thresholds based on Bus clockrate. The change to FiFo thresholds has reduced the number for 'eject' events.  I also change 'eject' from and ERROR to DEBUG.  An 'eject' event does not compromise i2c transmissions. It happens after a transaction has completed. 

Chuck.

* Allow using argument with attachInterrupt

* formatting

replace tabs with spaces

* fix bug more then 1 interrupt

* leftover

* add example

* make attachInterruptArg public

* update example

* leftover

If Core Debug Level is at DEBUG, a confusing debug message will be emitted if the I2C transaction takes longer complete than the  calculated minimum time.  This original debug message was just to prove that this new i2c code could correctly handle SCL stretching or interrupt latency issues. This delay is not a problem, or an error.  Usually it is caused by a higher priory interrupt starving the i2c ISR.  Usually WiFi is the culprit.  As long of this delay is within the configured timeout (by default 50ms, or can be set with Wire.setTimeOut(milliseconds);) no problem will occur and the transaction will successfully complete.
Chuck.

* Add PSRAM init and malloc funtions

* Rebuild IDF libs

* fix sdmmc config

* Fix warnings in EEPROM

from @Curclamas

* remove leftover TAG in EEPROM

* Initial add of @stickbreaker i2c

* Add log_n

* fix warnings when log is off

* i2c code clean up and reorganization

* add flags to interrupt allocator

* fix sdmmc config

* Fix warnings in EEPROM

from @Curclamas

* remove leftover TAG in EEPROM

* fix errors with latest IDF

* fix debug optimization (#1365)

incorrect optimization for debugging tick markers.

* Fix some missing BT header

* Change BTSerial log calls

* Update BLE lib

* Arduino-ESP32 release management scripted (#1515)

* Calculate an absolute path for a custom partitions table (#1452)

* * Arduino-ESP32 release management scripted
(ready-to-merge)

* * secure env for espressif/arduino-esp32

* * build tests enabled
* gitter webhook enabled

* * gitter room link fixed
* better comment

* * filepaths fixed

* BT Serial adjustments

* * don't run sketch builds & tests for tagged builds

* Return false from WiFi.hostByName() if hostname is not resolved

* Free BT Memory when BT is not used

* WIFI_MODE_NULL is not supported anymore

* Select some key examples to build with PlatformIO to save some time

* Update BLE lib

* Fixed BLE lib

* Major WiFi overhaul

- auto reconnect on connection loss now works
- moved to event groups
- some code clean up and procedure optimizations
- new methods to get a more elaborate system ststus

* Add cmake tests to travis

* Add initial AsyncUDP

* Add NetBIOS lib and fix CMake includes

* Add Initial WebServer

* Fix WebServer and examples

* travis not quiting on build fail

* Try different travis build

* Update IDF to aaf1239

* Fix WPS Example

* fix script permission and add some fail tests to sketch builder

* Add missing space in WiFiClient::write(Stream &stream)