| ??? 01/07/05 11:39 Read: times |
#84511 - Are you sure? Responding to: ???'s previous message |
Erik said:
For AC load only a very slight possibility since part of the quaint Antiquity of this "design" is that it uses an old 12 clocker at 11 MHz ( ~1MHz cycle) you should not have a problem, with such a processor you can, in most cases, live with total prop delays in the half microsecond range. Are you sure?? For instance, tWHQX (Data hold after !WR) is tclcl-25nsec (min.) for an AT89S52, which is about 70nsec at 11MHz clock frequency. If you have a design with an extended data bus and if you combine !WR with additional signals by the help of 74HCMOS gates, then you must take care about the timing issue very well. Proper timing analysis is always necessary, even if you use 'antiquities'... Also: Just mixed designs using analog and digital signals can highly benefit from using a slow anitquity, instead of your 50MHz clocker! These fast beasts can bring the hell onto your board!! But you are correct, of course: Using a separate EPROM while having today these fantastic FLASH-micros is a sin and even for studying purpose noone should choose such an oldfashioned solution. Kai |
| Topic | Author | Date |
| Worst case design | 01/01/70 00:00 | |
| bible time | 01/01/70 00:00 | |
| What about an example? | 01/01/70 00:00 | |
| loading analysis | 01/01/70 00:00 | |
| Laoding Analysis | 01/01/70 00:00 | |
| AC "loading" | 01/01/70 00:00 | |
| AC analysis | 01/01/70 00:00 | |
| AC loading | 01/01/70 00:00 | |
| Andy forgot | 01/01/70 00:00 | |
| Not so much | 01/01/70 00:00 | |
| How to post a schematic - Tutorial | 01/01/70 00:00 | |
| Analysis... | 01/01/70 00:00 | |
| Schematic | 01/01/70 00:00 | |
| ? | 01/01/70 00:00 | |
| new url | 01/01/70 00:00 | |
| Link | 01/01/70 00:00 | |
| Third time lucky | 01/01/70 00:00 | |
| the link | 01/01/70 00:00 | |
| Oh dear... | 01/01/70 00:00 | |
| Clock Freq. | 01/01/70 00:00 | |
| old school | 01/01/70 00:00 | |
| ADC | 01/01/70 00:00 | |
| 1997 | 01/01/70 00:00 | |
| ? | 01/01/70 00:00 | |
| Design Practices | 01/01/70 00:00 | |
| for the sake of it | 01/01/70 00:00 | |
| living in the past | 01/01/70 00:00 | |
| Old Design practice | 01/01/70 00:00 | |
| Call My Bluff? | 01/01/70 00:00 | |
| true meaning of "Worst-Case" | 01/01/70 00:00 | |
Are you sure? | 01/01/70 00:00 | |
| Business spec ? | 01/01/70 00:00 | |
| UniS? | 01/01/70 00:00 | |
| Naw | 01/01/70 00:00 | |
| Ya | 01/01/70 00:00 | |
| ? | 01/01/70 00:00 | |
| Try this | 01/01/70 00:00 | |
| can not answer | 01/01/70 00:00 |