| ??? 12/02/04 16:08 Read: times |
#82405 - RS485 'U' & ISP Responding to: ???'s previous message |
Hi Erik,
Thanks a lot for your reply, You can not ISP with 485. You need 422 or 232. On my 485 boards I have a connector for an external "miniboard" with a MAX232 (equivalent) for ISP purposes. I have e-mailed umpteen Philips persons about a "direction pin" during ISP to no avail. According P89V51RD2 datasheet, Upon power up P89V51RD2 tries to autobaud ISP, During this period if an Upper case letter 'U' is revieved it is used for autobaud setting and ISP firmware echo this 'U' and enters ISP mode. Due to an unfortunate chance if an 'U' was being transmitted on the Bus. When a machine is just turned on and trying to auto baud ISP wont' this 'U' cause the micro to enter ISP. Although there will be no programming due to half duplex stuff and since there are no hex records on the bus. But won't the micro get permanently stuck waiting for hex records. Regards, Prahlad Purohit |
| Topic | Author | Date |
| RS485 Contention. | 01/01/70 00:00 | |
| 485 ISP | 01/01/70 00:00 | |
| RS485 'U' & ISP | 01/01/70 00:00 | |
| the crux | 01/01/70 00:00 | |
| Flashmagic !!!! | 01/01/70 00:00 | |
| RS485 contention | 01/01/70 00:00 | |
| Cygnal F12x | 01/01/70 00:00 | |
| Reply to Erik | 01/01/70 00:00 | |
| FM< half duplex | 01/01/70 00:00 | |
| Reply to Erik | 01/01/70 00:00 | |
| bus direction | 01/01/70 00:00 | |
| A few comments | 01/01/70 00:00 | |
| comnments on comments | 01/01/70 00:00 | |
| comments^3 | 01/01/70 00:00 | |
| boot NIT | 01/01/70 00:00 | |
An example worth 3E8h words :-) | 01/01/70 00:00 | |
| A fundamental query - Erik | 01/01/70 00:00 | |
| testing | 01/01/70 00:00 | |
| RS 485 Contention | 01/01/70 00:00 | |
| RS485 Contention | 01/01/70 00:00 | |
| Switch ? | 01/01/70 00:00 | |
| RS485 contention | 01/01/70 00:00 | |
| Possible solutions. | 01/01/70 00:00 | |
| Thanks Erik. | 01/01/70 00:00 | |
| SOLUTION | 01/01/70 00:00 | |
| Thanks but thats not the solution | 01/01/70 00:00 |