Hi, I’m looking for a way to generate 2 different one-shot pulse using 1 input.
For example, a circuit would have one input and 2 outputs.
if input becomes high, then output1 would pulse high for 200ms, but only one time. It would not pulse again.
if input becomes low, then output2 would pulse high for 200ms, output1 would NOT pulse.
I’m trying to wrap my head around a 555 to do this but I can’t really determine how to. I’m thinking there might be a chip that does something like this already.
Anyone can direct me to a product that would help me? or some key search words I could google for? because I don’t even know if such a concept has a name.
I don’t have a diagram of how to set it up, but two 555’s or a single 556 timer IC should work. You might need some transistors or digital logic on your input to change modes when you switch from high to low though.
Forrest M. Mimms III had an excellent series of mini notebooks and books that have tons of 555 circuits in them and one of those might be helpful in pointing you in the right direction. We carry one of his books and the other I found in an online PDF. Links to both are below.
- [[Forrest Mims - 555 Timer IC Circuits](https://archive.org/details/Forrest_Mims-engineers_mini-notebook_555_timer_circuits_radio_shack_electronics/mode/2up)
Thanks for the info. You’re basically confirming that there are no IC that would provide a full solution then.
So to reduce the footprint, keep costs down and simpler design, I guess that using a attiny and implementing the logic in softtware would be a better option then
While there isn’t a chip designed to do specifically what you’re looking to do, there are ways to use a single chip to replicate your desired results but they take some work to get functioning.
A small micro controller will do this, but you would need to write a little bit of software and upload that to the chip that can take your inputs and give you the outputs you’re looking for. A good place to start with that would be an [Arduino Uno since it’s USB enabled and you can upload your code through USB using the [Arduino IDE. There are [smaller versions of the Uno that you could move to later to save space, or you could with the right programming tool put everything into a [single micro controller chip when you’re ready.
An advantage of using a micro controller is that you can easily alter your code and re-upload it to the Arduino Uno (or bare chip) to make changes to how it operates while with a few 555’s, you need to change the wiring or components to alter their behavior.
after experimenting a while, I think that this would do exactly what I need:
http://tinyurl.com/t7ggc59. But the problem with this is that the pulse length would be variable depending on how much time has elapsed to discharge the capacitor (if I toggle the input pin rapidly or if let it on/off for 30sec.) But using this, the footprint would be quite large if I need 10 of those. So I might have to consider using a CPLD I guess.
But then I found the sx15109 board (https://www.sparkfun.com/products/13601 … 1551221942). It would change my workflow a bit because I wouldn’t drive a GPIO but rather send commands through the i2c bus. I see there is a “one-shot mode” where I can send a command and a pin on the sx board would pulse.