| ??? 10/06/05 11:55 Read: times |
#102024 - but Atmel Responding to: ???'s previous message |
hi,
Jan Waclawek said:
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).
Atmel calculates baudrate by measuring of 8 bits. They start timer2 at beginning of bit 0, wait for low bits 1/3/5/7 and for high bits 2/4/6/stop. Then they stop timer2, tune its value, multiply it by 3 and divide by 64. This results in f/6*8*3/64 = f/16 value which then is complemented to 65536 and loaded in timer 2 reload register. It seems this way more appropriate than Philips does. Regards, Oleg |
| 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 |