Startup information, including board configuration, is only printed when module esp_log_startup is used. This reduces the amount of information that is printed by default to the console during the startup. The user can enable module esp_log_startup to get the additional startup information.
UART FIFO must contain only 1 byte when newlib's `printf` function is used. Otherwise, outputs that are still not sent over UART are lost when `printf` is called asynchronousely.
In the `pwm_set` function, the switch-on and switch-off times for PWM channels were only determined for the following phase, but not for the current phase. This could result in a missing duty cycle when calling the function `pwm_set` if the switch-on time of the current phase was not yet reached or to an extended duty cycle if the switch-off time of the current phase had not yet been reached.
The commit
- improves the timing of the SDA and SCL signals that fixes communication problems with some slaves (#10115),
- introduces the internal function _i2c_clear which clears the bus when SDA line is locked at LOW, and
- renames internal _i2c_*_sda and _i2c_*_scl functions to function names that are more clear, e.g., _i2c_clear_sda to _i2c_sda_low.
