Supplier of switch
- Thread starter dbarry722
- Start date
Oops, think I've found the one I need. Just a basic spring loaded switch that connects say pin 3 to logic low but when pressed bring the pin to logic high then back to logic low when switch let go
http://www.rapidonline.com/pdf/75-0130.pdf
Declan
http://www.rapidonline.com/pdf/75-0130.pdf
Declan
"...a switch that when connected keeps a pin at logic low but when momentarily pressed brings it to a logic high."
This can be done with any normal push-to-make. It's basically how all my button inputs work. Dunno why you would need a push-to-break. See Manual 3 page 26. The first example shows how to do exactly what you asked.
This can be done with any normal push-to-make. It's basically how all my button inputs work. Dunno why you would need a push-to-break. See Manual 3 page 26. The first example shows how to do exactly what you asked.
Hi folks.
I discovered that if my input was floating, strange things happened. Maybe I was just the strange one
So, what I was after was a switch that would initially keep it at logic low but when pressed momentarily, took it to logic high then bak to logic low when released.
Off to do a bit of reading as to what states pins can be left in.
Declan
I discovered that if my input was floating, strange things happened. Maybe I was just the strange one
So, what I was after was a switch that would initially keep it at logic low but when pressed momentarily, took it to logic high then bak to logic low when released.
Off to do a bit of reading as to what states pins can be left in.
Declan
Hi Declan,
Yes, as Boriz (and the manual) says, you can have either "Active High" or "Active Low" depending on whether you connect one of the switch contacts to the supply rail or to earth (and the pull-down/up resistor to the other rail). The resistor is essential.
However, the quality/performance of some of the cheap "push to make" (and even worse "push to break") button switches can be very poor. If your project is in any way safety-related, I would ensure that the switch employs a sliding (self-cleaning) contact (not easy to determine from the outside). Or even better use a "microswitch" style (as shown in the left-hand image on the same page 26 of the manual) which will also give you reliable make and break contacts. Thus you could avoid using any resistors (those switches are always "break before make" so the NO and NC pins could be connected directly to supply and earth), but I'd still recommend that you do use resistors.
Cheers, Alan.
Yes, as Boriz (and the manual) says, you can have either "Active High" or "Active Low" depending on whether you connect one of the switch contacts to the supply rail or to earth (and the pull-down/up resistor to the other rail). The resistor is essential.
However, the quality/performance of some of the cheap "push to make" (and even worse "push to break") button switches can be very poor. If your project is in any way safety-related, I would ensure that the switch employs a sliding (self-cleaning) contact (not easy to determine from the outside). Or even better use a "microswitch" style (as shown in the left-hand image on the same page 26 of the manual) which will also give you reliable make and break contacts. Thus you could avoid using any resistors (those switches are always "break before make" so the NO and NC pins could be connected directly to supply and earth), but I'd still recommend that you do use resistors.
Cheers, Alan.