| ??? 06/09/06 15:10 Read: times |
#118101 - Being careful... Responding to: ???'s previous message |
Richard said:
When I need a delayed pulse, I prefer to build my own, which, by the way, I very seldom do, using a schmidt-triggered nand gate, with the same input to both inputs, albeit one delayed via series resistor followed by a cap to GND. This is essentially what a one-shot is, with the exception that one can calculate the time between the beginning and end of the delay. Ganeshan, if you read between these lines, some very important point can be seen: Richard obviously knows, when the triggering edges arrive! This is a basic requirement for working successfully with a monoflop (even it its retriggerable) or its simpler variant Richard mentioned above: When using a monoflop you should always know, when it is triggered, in relation to the whole pulse and especially to the back edge. This is also violated by your application: You do not know when the pulses arrive as you suffer from switch bounce. And what the micro fabricates with an erratic and unpredictable pulse train at its reset pin, we can guess... Again, use the MAX1232 with its /PBRST input for this purpose. This chip was designed to provide stable reset pulses. Kai |
