| ??? 02/25/08 13:17 Modified: 02/25/08 13:18 Read: times |
#151393 - nit really ... but Responding to: ???'s previous message |
Is there any rule of thumb for the 8051/8052 as far as resistor sizing is concerned that is a safe place to start?
for the pullups, there are the "grab bag values" these values apply only to signals that do not leave the board. if the load is purely CMOS 'grab' 10-22k if the load ia TTL or such 'grab' 2k2- 4k7 otherwise calculate. Now, if you are using a very fast derivative, you will find that such allow you to configure ports as push-pull which, of course makes a pullup wrong. If you with resistive pullups go much beyons the 'regular' derivatives, (speedwise) you will, at times, for fast signals have to take the load capacitance in consideration. In other words use "grab bag values" for the 'normal, slow' things and calculate otherwise. noe, since this is "grab bag" some will, I am sure, come in with different values, it is a matter of preference. Erik |
| Topic | Author | Date |
| check my interfacing scheme please? | 01/01/70 00:00 | |
| Schematic is not clear to me atleast | 01/01/70 00:00 | |
| too big input resistors | 01/01/70 00:00 | |
| of course, you will | 01/01/70 00:00 | |
| Judging from the picture on the home page ... | 01/01/70 00:00 | |
| the FAQ has it all | 01/01/70 00:00 | |
| my apologies | 01/01/70 00:00 | |
| No need to apologize, Brian... | 01/01/70 00:00 | |
| thank you | 01/01/70 00:00 | |
| nit really ... but | 01/01/70 00:00 | |
thank you | 01/01/70 00:00 | |
| dont know other way | 01/01/70 00:00 |