The former correction factors were determined by measuring the resulting clocks without a device connected to the bus.
However, when testing the changes for low CPU clock frequencies, it was figured out that the clocks not only depend on configured register values
_i2c_hw[dev].regs->scl_low_period.period
_i2c_hw[dev].regs->scl_high_period.period
but also on the bus capacity. Obviously, the register values are not absolute times in APB clock cycles, but rather times that start as soon as the corresponding level is reached. In this case, the higher the bus capacity, the longer the period would be.
This means that the clock speed cannot be precisely controlled via the correction factors anyway. For this reason, and because the I2C implementation in ESP-IDF also does not use correction factors, they were removed.
When entering a sleep mode, all wake-up sources should first be disabled before the wake-up sources required for the sleep mode are then stepwise enabled again. Otherwise, an wake-up configuration of one sleep mode may affect the wake-up within another sleep mode.
The WiFi interface should be stopped before reboot or sleep. But stopping the WiFi interface disconnects an existing connection. Usually, esp_wifi_netdev tries to reconnect on an disconnect event. However, trying reconnect with a stopped WiFi interface may lead to a crash. Therefore, the stop event has to be handled.
Now, where the vendor files for light/deep sleep mode are added, function `pm_off` does not need to implement this mode by itself. Instead the existing deep sleep with disabled wakeup sources is used for pm_off.
`rtc_init` is used after light sleep to update the system time from RTC timer. The fix corrects a small difference of about 230 ms which would sum up with each wakeup from light sleep.
By using a custom EPOCH for the RTC implementation, we can extend the
range of the 32 bit counter based RTC by 118 years.
It also reduces the code size compared to the stdlib based POSIX functions.
