How to use pb6 and pb7 atmega328 ports on arduino pro mini?

Question

Arduino

( https://www.arduino.cc/en/Hacking/Atmega168Hardware )
A crystal oscillator hangs on these ports. There is a need to unsolder it and solder it as to the input / output ports. What software changes need to be made to make this work?
PS Preferably using arduino ide, I don't think I'm ready for pure avr.

Answer 1

To do this, you need to reflash the so-called fuses (fuses), which determine the configuration of the MK crystal.
In particular, they specify the choice of clock generator. You need to reprogram them from an external crystal to an internal RC oscillator. There are 2 problems here:
1 - you need an additional ISP programmer. They can be arduino, as an option. I don't know any other way to flash fuses.
2. Clocking accuracy on the internal RC oscillator is significantly lower than with a quartz resonator, this should be taken into account if accurate timings are needed.
www.engbedded.com/fusecalc - here you can calculate the fuses for your MK.

Answer 2

What exactly do you need these pins for? If you don’t have enough ports, then you can use multiplexers or switch to mega, but because of two pins, it’s overkill to change the controller for internal quartz.