I am looking at designing a low-power project that will have an ATMega328 running at a low speed for lower power consumption.
The current plan is to have the UART hooked up to a RF Link Receiver for communication at 1200baud.
What I'm wondering, though, is what the minimum speed is that I can run an ATMega328 at and still have a 1200baud UART running. Is 1MHz fast enough?
Best Answer
The UART clock runs at 16 times the baud rate. So you would could get possibly get away with 19.2 kHz. 1 MHz will be fine.
Most often you would run at a clock rate that gives a convenient divider to generate the UART baud rate clock and is still faster enough for any other processing you need to get done. Each time a byte or packet is transmitted via the UART, put the CPU into a low power mode and wake up again on an interrupt when more data is ready.