| ??? 10/06/05 07:40 Modified: 10/06/05 07:41 Read: times |
#102014 - RTFM Responding to: ???'s previous message |
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. "Ultra-High-Speed Flash Microcontroller User's Guide (http://www.maxim-ic.com/products/microcontrollers/pdfs/DS89c420_user_guide.pdf) on page 129 said:
Crystal Frequency
ROM Loader_Baud rate = ------------------------
192 x( 256-Timer Reload )
Timer reload values attempted by the loader: FF, FE, FD, FC, FB,
FA, F8, F6, F5, F4, F3, F0, EC, EA, E8, E6, E0, DD, D8, D4, D0,
CC, C0, BA, B0, A8, A0, 98, 80, 60, 40On 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? A note: the bootloader in DS89C4x0 unfortunately uses timer1 for baudrate generation, hence those limitations. 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 |