I would like to ask if I understood datasheet (Atmega328P http://www.atmel.com/images/atmel-8271-8-bit-avr-microcontroller-atmega48a-48pa-88a-88pa-168a-168pa-328-328p_datasheet.pdf) correctly.
I need stable clock for U(S)ART.
As ka7ehk said in :
Internal oscillator is often not accurate enough for baud rate setting.
The true operating baud rate of the two UARTs need to be within (about) 4% of each other. Internal oscillator CAN be further off than that.
So I need crystal oscillator lets say 8Mhz and connect it to PB6 and PB7 pins.
I also need to achieve long sleep times (1-2 min.)
Timer2 can wake up uC and is 8-bit. To achieve long sleep Timer2 should be fed with 32KHz Low-frequency
Crystal Oscillator on the same pins(PB6 and PB7).
If this above is OK then I can't do it like this, right?