| ??? 10/22/05 12:26 Read: times |
#102761 - why? Responding to: ???'s previous message |
hi,
Shawn Nemat said:
Suppose I were to clear IE.7 for a few ms, and in that time my level-triggered external interrupt fires. When I set IE.7 again will the interrupt be handled or ignored? In "level-triggered" mode an external interrupt flag is just inversion state of detected pin`s level. Note: in this mode even you clear interrupt flag (IE0, IE1) nevertheless it does not really clear flag as long as source keeps low level at the pin. And in this case if you come out from ISR thinking that you did clear the flag, your program will be re-routed to ISR vector again. Are you sure that you need with this mode really? This mode may be useful for example, as handshake when in ISR you send to source the presence answer and peripheral removes low level from a pin then. For regular interrupts it is not so good choice. Regards, Oleg |
| Topic | Author | Date |
| interrupts recieved during downtime | 01/01/70 00:00 | |
| Bible says | 01/01/70 00:00 | |
| I saw that too | 01/01/70 00:00 | |
| sample and hold | 01/01/70 00:00 | |
| thus the cirrect answer to the original | 01/01/70 00:00 | |
| Correct ? | 01/01/70 00:00 | |
| if it is level, it need to remain | 01/01/70 00:00 | |
| yes | 01/01/70 00:00 | |
| If this is what you ment then | 01/01/70 00:00 | |
| Interrupt | 01/01/70 00:00 | |
| why? | 01/01/70 00:00 | |
| here's why | 01/01/70 00:00 | |
eh... | 01/01/70 00:00 | |
| sample and hold | 01/01/70 00:00 |