I wan't to produce a high to low output pulse when the input is Low to High

Thread Starter

akeepan

Joined Feb 24, 2020
9
This High to Low output is fed to 8051's interrupt pin, can anyone help me with a simple way of producing a square wave of this type either using TTLs, 555 timers, oscillators or any other methods. I don't want to use another MCU to produce this pulse?
Thank You
 

AlbertHall

Joined Jun 4, 2014
9,826
There are many circuits for '555 on www.
There are also ready built '555 modules available.
What pulse width do you want?
Do you want it to run continuously or produce just a single pulse perhaps when a button is pressed?
What voltage level do you need?
 

Thread Starter

akeepan

Joined Feb 24, 2020
9
There are many circuits for '555 on www.
There are also ready built '555 modules available.
What pulse width do you want?
Do you want it to run continuously or produce just a single pulse perhaps when a button is pressed?
What voltage level do you need?

Thank You for the reply Albert
Untitled.png
This is a water level detector
The SEN_1 to SEN_5 will be kept in water and I will be connecting each black lines on the picture to separate base of transistors, transistors will be connected in serious and one end to VCC and the other end of it to the interrupt pin. Because I am using the interrupt pin as edge triggered there wont be an issue when the water level is getting low(because the the pulse will be from high to low), but when the water level is raising the transition will be from low to high so i want to figure out a way to convert the signal in to a high to low.
I only want a single pulse
pulse width must be at least 2us vs 2us
The chip's voltage chracteristics are
Untitled1.png
 

danadak

Joined Mar 10, 2018
4,057
Your inputs should have hysteresis to eliminate noise triggering of ISR. This can
be accomplished with external comparators or using a processor with A/D to sample
inputs and implement the necessary hysteresis. Or one with a scanning sampled
comparator.

An example, single chip, no external transistors needed. Most of chip resources not
used, could be used for other stuff. See right hand window.

Compiler and IDE (PSOC Creator) free. https://www.cypress.com/products/psoc-creator-integrated-design-environment-ide

Dev board, low end $ 10 would work - https://www.cypress.com/documentation/development-kitsboards/cy8ckit-059-psoc-5lp-prototyping-kit-onboard-programmer-and



1585133784738.png


Regards, Dana.
 
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