| ??? 10/06/05 10:34 Read: times |
#102023 - 10472 baud Responding to: ???'s previous message |
At 8MHz the reload value of FC (-4) gives 10416.67 baud. Divider of 11 at the PC gives 10472.73 baud. The difference is about 0.5%. This should work.
But speaking of autobauding, I don't know the method how the Dallas bootloader does it, but I investigated the Philips' P89V51RD2 bootloader's autobaud. As they "measure" a bit's time using jb and jnb, there is an inherent uncertainty of determining the proper baudrate (4 cycles) especially if there is an assymetry in the duration of "1" and "0" bit (which is almost always the case). The consequence is, that with higher baudrates there is a nonzero probability that you will get "garbled" output after (incorrect) autobauding even if you use the "proper" crystal and baudrate. I have prepared a xls sheet ( http://www.efton.sk/t0t1/autobaud_error.htm ) where this can be tried out easily (again, this is for P89V51RD2 (AFAIK valid also for P89C51RD2)). Jan Waclawek |
| Topic | Author | Date |
| Other crystals? | 01/01/70 00:00 | |
| my experience | 01/01/70 00:00 | |
| dallas | 01/01/70 00:00 | |
| RTFM | 01/01/70 00:00 | |
| the speedy '450 | 01/01/70 00:00 | |
| why 8MHz? | 01/01/70 00:00 | |
| crystals | 01/01/70 00:00 | |
| '420 | 01/01/70 00:00 | |
| errata? | 01/01/70 00:00 | |
| 22.1184MHz | 01/01/70 00:00 | |
| since when? | 01/01/70 00:00 | |
| the tiny asterisk... | 01/01/70 00:00 | |
| Baud rates | 01/01/70 00:00 | |
| crystals, but problem fixed.... sorta :) | 01/01/70 00:00 | |
| 10472 baud | 01/01/70 00:00 | |
| but Atmel | 01/01/70 00:00 | |
| 8 bits autobaud | 01/01/70 00:00 | |
| explanation | 01/01/70 00:00 | |
| dallas | 01/01/70 00:00 | |
| 7.3728MHz | 01/01/70 00:00 | |
| Lower clock frquency | 01/01/70 00:00 | |
| backslashes | 01/01/70 00:00 | |
| New Server Problems? | 01/01/70 00:00 | |
| lol | 01/01/70 00:00 | |
| Go on laughing... | 01/01/70 00:00 | |
| rise/fall time? | 01/01/70 00:00 | |
| that is absolutely correct, but what mak | 01/01/70 00:00 | |
| jetplanes | 01/01/70 00:00 | |
| It's a combination of both | 01/01/70 00:00 | |
| thread | 01/01/70 00:00 | |
This is for the XA which has a UART that | 01/01/70 00:00 |