| ??? 05/22/06 18:10 Read: times |
#116875 - Thanks JG - It works now Responding to: ???'s previous message |
Thanks Joe for pointing me in the right direction. I was using the P1.0 line of the 89C2051 to control the 89LPC9408 reset line and relying on the weak internal pull-up on the reset line. Adding a 4.7K (or as you like to say 4K7 in Aus) pull-up resistor fixed the problem and I am now able to put the 89LPC9408 back into ISP mode at will.
The 89LPC938 data sheet says that the "min" rise time requirement for the P1.5 (reset line of the 89LPC9408) for "signal acceptance" is 125 nSec but there is no maximum stated. This seems somewhat ambiquous to me. Perhaps the data sheet means that the minimum acceptable rise time is 125 nSec MAX. The 89C2051 circuit is a lot simpler than the Keil circuit (which I did find earlier). I will now investigate the other non-hardware means of reasserting ISP mode. Regards, Bert |
| Topic | Author | Date |
| 3 pulse ISP entry for P89LPC938 | 01/01/70 00:00 | |
| 3-pulse | 01/01/70 00:00 | |
| you did not read did you? | 01/01/70 00:00 | |
| P89LPC9408 Programming | 01/01/70 00:00 | |
| how can down under be over the rainbow? | 01/01/70 00:00 | |
| Thanks JG - It works now | 01/01/70 00:00 | |
| 3pulse circuit | 01/01/70 00:00 | |
| LPC900 ISP and IAP etc | 01/01/70 00:00 | |
| it IS in ISP mode the first time | 01/01/70 00:00 | |
| LPC900 ISP and IAP etc | 01/01/70 00:00 | |
| Link to 3 pulse circuit using 89C2051 | 01/01/70 00:00 | |
| Oh, yes. | 01/01/70 00:00 | |
| I DO know that Erik - | 01/01/70 00:00 | |
| actually it does not | 01/01/70 00:00 | |
| Break feature | 01/01/70 00:00 | |
P89LPC938 | 01/01/70 00:00 |