On Thu, Jun 12, 2008 at 12:33 PM, Vasile Surducan wrote: > On 6/11/08, Matthew Miller wrote: >> On Wed, Jun 11, 2008 at 10:42:24PM -0400, M. Adam Davis wrote: >> > Better designed internal oscillator, less sensitive to temperature and >> > voltage change (perhaps temperature compensated?). >> > >> > Don't count on it for RS-232 and other timing applications if you plan >> > to run it to its extremes in temperature or voltage - it can vary as >> > much as +/-3.2% or so ( see figures 18-39 to 18-42 for graphs) which >> > is greater than the 2.5% I usually restrict myself to when talking >> > about RS-232 acceptable clock error. >> > >> > Still, if you drive it with a reasonable voltage, and stay within a >> > restricted temperature range, then it should work reasonably well (ie, >> > +/- ~1%). >> >> Right now at 5V and room temp. 9600 buad and 1 minute measurements work well >> with the 16F689. I'll soon see how that 1 minute timer works in full sun >> shine and using 3AA batteries. Data transmission over serial can occur >> in-doors, but hopefully the 1 minute interval won't change too much. > > My experience with 16F676 and internal oscillator at 115200 is not very good. > How many boards have you tested and on how many computers ? > Sice then I'm not using only zero error crystals for communications > and believe me it worth. The error doesn't change with baudrate. I've used the internal 8MHz with 16f688 at 115200 baud, 120 copies and had no problems. The message format had a checksum, however. And they were fed linear-regulated +5V and kept at indoor-office temperatures. Regards, Mark markrages@gmail -- Mark Rages, Engineer Midwest Telecine LLC markrages@midwesttelecine.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist