| ??? 03/31/09 16:22 Modified: 03/31/09 16:25 Read: times |
#164071 - I know that some use antiques, but ... Responding to: ???'s previous message |
Take care that you never write a "0" to P2.0 as long as your 74HCT165 is connected to the micro! The reset level of P2.0 is "1" helping you to keep the 74HCT165 intact after power-up. But remember that there can be a brief period of time between supply voltage rise-up and reseting the port pins, where the port pins' status can be undefined. This happens usually with micros not being able to provide an asynchronous reset. I'm not familiar with your micro, but this behaviour can result in momentary shorts and damage.
... unless your derivative (which you, as so many others, do not think matters - IT DOES) is bought in an antique shop you can disregard the above. I know of no modern '51 derivative without asynchronous reset. Ah, coming to think of it ... there is another reason no to disregard, and that is if you are totally ignorant of the reset mechanisms and use a RC reset. Erik |
| Topic | Author | Date |
| Pulling to 0 | 01/01/70 00:00 | |
| chips | 01/01/70 00:00 | |
| 89C450 | 01/01/70 00:00 | |
| Set a pin as input | 01/01/70 00:00 | |
| Port pin as an input | 01/01/70 00:00 | |
| Put load on HCT output | 01/01/70 00:00 | |
| Checking | 01/01/70 00:00 | |
| I see what you want to do there ... but ... | 01/01/70 00:00 | |
| so check 74hc165 with resistive load only | 01/01/70 00:00 | |
| It's not uncommon... | 01/01/70 00:00 | |
| I know that some use antiques, but ... | 01/01/70 00:00 | |
| Do we mean the same? | 01/01/70 00:00 | |
| I asid 'modern', not Arghmel | 01/01/70 00:00 | |
| Come on, Erik.... | 01/01/70 00:00 | |
| now let me get this straight ... | 01/01/70 00:00 | |
| one thing I always do ... | 01/01/70 00:00 | |
| Shame on me! | 01/01/70 00:00 | |
| Oops! | 01/01/70 00:00 | |
| Been there, done that | 01/01/70 00:00 | |
IO expansion | 01/01/70 00:00 |