| ??? 10/06/05 07:53 Read: times |
#102017 - the speedy '450 Responding to: ???'s previous message |
Jan Waclawek said:
Jeff Corr said:
I'm using the Dallas 420 derivative. I built a board last night which I'm having problems with in that it will not get into the boot loader. I've got an 8Mhz crystal in it. Reason I was asking is because in that table there (from the link you gave me), you can clearly see 8Mhz is supported at several baud rates for the bootloader, but in the Dallas datasheets there is no such table. You should READ the manual. Yes, it is long, and a bit messy (Dallas...) but it IS worth reading it if you mean it seriously with the DS89C420. It looks like you type faster than me. :) On the following page there is exactly the table which you need... Yes, the 8MHz is not in the table, but you can use the value given for 16MHz and divide it by two :-)... Or consider using a different, more "standard" crystal value. The DS89C4x0 can go up to 33MHz, isn't it a pity to waste it's horsepower using low clock? Not necessarily. There is plenty of performance to be gained just dropping the '450 into a standard 8051-based circuit by virtue of it being a single clock device. At 33 MHz, you'll be hard pressed to meet the timing constraints of a lot of the peripherals you might want to use with it (at least without stretch cycles). Furthermore, the EMI issues you'll see at this speed, especially if you have external bus accesses, can be nontrivial. --Sasha Jevtic |
| 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 |