Problem with two "generic pulse counter"

[Ruprecht]

I'm trying to automate the heating control of our pool. When connecting two flow sensors there is currently a problem because the measured value of one of the flow sensors is inconsistent or incorrect.

The first sensor connected to GPIO14/D5 works. The second sensor which is connected to GPIO13/D7 supplies incorrect measured values ​​at the same flow which are always too low by a factor of 2 - 4. If I swap the connections of both sensors then the sensor which is connected to GPIO14/D5 will always work properly. I have already tried to connect the second sensor to GPIO12/D6, but also the same error there. Both sensors work perfectly and the signal at GPIO has perfect rectangular shape 0/3.3V.

Is there any problem if a generic pulse counter is connected to GPIO13/D7 or GPIO12/D6, or why does this not work?


The flow sensor is: https://de.aliexpress.com/item/DN25-pip ... 17688.html

The adjustment to the 3,3 Volt level i have done with this circuit for each flow sensor:


The software is "ESPEasy_mega-20180818 Normal":

[TD-er]

Have you also tested to run only one sensor on the pins that now give the wrong value?

[Ruprecht]

In each case only that flow sensor shows correct values which is connected to GPIO14/D5. At the expected water flowrate up to 50 liters/min there should be a pulse rate of 288 Hz - Pulse (Hz) = [4,8 * Flowrate Q (liter/min)].

On GPIO14/D5 this works fine, but GPIO13/D7 or GPIO12/D6 only counts a fraction and wrong. Unfortunately, no such restriction is mentioned here in the wiki.

Because in my circuit GPIO2/D4 is occupied with 3 temperature sensors and GPIO4/D2 and GPIO5/D1 is occupied by the I2C-interface, there is probably no further possibility to connect my two flow sensors.

[Ruprecht]

OK, I measure the flowrate alternately. With a small relay, I turn each 1 flow sensor on the input GPIO14/D5 - problem solved