Take the 2-minute tour ×
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It's 100% free, no registration required.

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?

share|improve this question
add comment

1 Answer 1

up vote 9 down vote accepted

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.

share|improve this answer
    
Excellent, thanks for the info :) –  robzy Nov 30 '09 at 7:56
    
I think the sentence "The UART clock runs at 16 times the baud rate" is a little bit misleading. The USART baud rate generator runs on the system/oscillator clock and is just prescaled by the UBRR value. Also, it depends on the operation mode. The factor 16 applies to "Asynchronous Normal mode". –  Rev1.0 Feb 26 '13 at 19:52
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.