On 5/17/07, Gerhard Fiedler wrote: > Vasile Surducan wrote: > > > On 5/16/07, Jim wrote: > >> I am using RB4-RB6 inputs to detect changes to a couple of Normally closed > >> switches and raise an interrupt. This technique I have used successfully in > >> the past, But I also have a number of Normally Open switches on RC0 - RC5 > >> that I want to trigger a RB interrupt too. What I am proposing is to add a > >> 1N4148 diode pointing to the RB input from each of the RC switches in DDL > >> style - Is this likely to work? What should I watch for? > >> > >> > >> > >> > >> +5v > >> --+-- > >> | > >> | > >> \ > >> / Pullup R > >> \ > >> / > >> | > >> | NO Switch > >> To Pic ----+-----------O O--------+ > >> RC Input | | > >> | | > >> ---- | > >> \/ | > >> ---- --- > >> | GND > >> | > >> To Pic --+ > >> RB Input > > > Maybe in the configuration below, a pull down resistor on RB > > (10K-100K) will help having a controlled current flow through diode. > > When NO will be closed, the falling edge may be sensed on RB. > > A pull-down resistor would create a voltage divider with the pull-up, > wouldn't it? 3k3 pull up and 100K pull down? -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist