There is an error when the start byte NACKs
The nack sets the stop bit twice which keeps the stop bit high the next time
When the stop bit is high it creates a timeout when trying to use
This commit fixes so when a NACK occures on the address it doesn't stop twice
Refactors i2c_2 to match the structure of i2c_1 better.
Corrects functionality issues.
Allows the common implementation of read_regs and write_regs.
Documents constraints of hardware.
Matches error messages with API.
This commit fixes configuration problems when trying to use i2c pins that need to be remapped.
All B8 and B9 pins for STM32F1 need to be remapped, so a check is done if the remappable pins are selected.
