We have been facing a random problem where data sent to the ATMega128 on one of the UARTs (UART1 multiplexed on ports PD2 and PD3) gets corrupted. We have verified that the data being transmitted on the line by the sending device is correct (we can see this on a console terminal) so it is clear that the corruption is happening within the ATMega. We also read the ATMega UART registers and figured out that Frame Errors were occuring. The baud rate was 38400. We brought it down to 9600 but the problem still persists. One of the suspects is the clock stability; we are using the internal RC oscillator of the ATMega.
Have UART data corruption issues been seen when using the internal oscillator? At what baud rates? We have Atmel's application notes for calibration of the internal RC oscillator but we need some time to try that out. Has anyone tried out calibrating the internal RC oscillator ? If so, any tips ? Operating conditions: 3.3V 25C internal RC oscillator. Rgds, -Ved -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Uwe Fechner Sent: Thursday, April 06, 2006 4:55 AM To: AVR-GCC-list Subject: Re: [avr-gcc-list] Re: ATmega168 FreeRTOS code David VanHorn wrote: > Just for grins, the internal RC isn't all that stable over temperature > and VCC variations. While you can tweak the osc in at a given temp and > VCC, it will drift out again as these change. You should at least use > a resonator if you are doing serial comms. Well, this would not be good for my concept reducing power supply current. Only RC oscillator is fast enough to start, to make it possible, to have about 50..100 µs aktive cpu time every 2 ms. The improvement, that is still missing, is to recalibrate the RC oscillator at runtime using the quarz driven rtc. Regards: Uwe Fechner _______________________________________________ AVR-GCC-list mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/avr-gcc-list _______________________________________________ AVR-GCC-list mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
