Hi Garst and list, I have played a little with the fet140_fll2.c example from the TI fet tools package.
Using a freqency counter the DCO seems rock solid, but my old Tek 210 dso don't like it, i suppose this has to with jitter. As my power requirements arent that low, im using a HF crystal on XT2. I hope this may help you a little. Best regards, Jens ----- Original Message ----- From: "Garst R. Reese" <[email protected]> To: "mspgcc-users" <[email protected]> Sent: Wednesday, January 26, 2005 8:27 AM Subject: [Mspgcc-users] [RFC] Precision DCO for F161x > Background: > Steve has pretty much convinced me of the power savings advantages of > DCO, but I worried about providing a reliable and sufficiently accurate > clock for a 115200 serial line. For this purpose, I was using a > 3.684MHz crystal. Although Fredic reports reports success with DCO and > the FLL algorithm (not applicable to the F161x parts), I am still > concerned about part variation. > The solution I am considering is to use one of the DACs to drive Rosc. > The initial setting of DAC would be 2.6V, midway beween 2.2 and 3V. Rosc > would be either 200k or 100k depending on frequency requirements of the > application. These values are available at 25ppm from KOA Speer as 0805 > parts (RN32ALTD1003B25, RN32ALTD2003B25). The 100k resistor would allow > me to go to 7.368MHz. > In my application, I am also using a DS1390 RTC with battery backup, > which outputs a 32768Hz signal connected to TB0. > The general idea is to use RSELx and DCOx to get into the ballpark, and > then use the DAC to fine tune the frequency. > > Is this stupid, overkill, or what? > Flames welcome. > Garst > > > ------------------------------------------------------- > This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting > Tool for open source databases. Create drag-&-drop reports. Save time > by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc. > Download a FREE copy at http://www.intelliview.com/go/osdn_nl > _______________________________________________ > Mspgcc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/mspgcc-users > > > -- > No virus found in this incoming message. > Checked by AVG Anti-Virus. > Version: 7.0.300 / Virus Database: 265.7.3 - Release Date: 24-01-2005 > -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 265.7.3 - Release Date: 24-01-2005
