MSP430F449: US14 failure rate

Hello Anders,

The error rate you are seeing is in line with the timing settings you are using. Please see Table 17-2. Commonly Used Baud Rates, Baud Rate Data, and Errors in the device user guide for more information.

for the USART peripheral, using 9600 baud with an 32768Hz Xtal gives an error rate or ~1.75%.US14 errata can certainly contribute to that, but what you are seeing seems mostly in line with your settings.

Hello Anders,

Ahh, yes after further review it seems I have made a mistake of interpreting this chart as well. It's not that the error is a value of 21/12 (or 1.75), but that it has a max possible error of 21% in one direction and max possible error of 12% in the other. Direction of course is referring to if the sampling is behind or ahead of valid data. sorry for the confusion there.

As you can see, The error rate you are seeing is less than the calculated error rate of the setup of the part in this configuration. US14 is not really a concern at this time. If you need to reduce the error rate then I suggest lowering the baud rate for your communication on this part. Other alternatives include adding CRCs or other error checking methods within your communication so you can resend UARt packets if an error occurs; Driving the BRCLK with a higher frequency to reduce errors. Having a BRCLK of 32768 Hz with a baud rate of 9600 is not a good ratio for UART communication.

The last alternative would be to move to an MSP430 that has an USCI or eUSCI module which has better performance on UART and typically these devices have more frequency options to drive BRCLK. This is important as the higher the BRCLK to baud rate ratio, typically less error occurs.