im going to attempt to use the PCF8591 for monitoring a float sensor circuit. when the float sensor is closed it will pull an analog pin on the PCF8591 LOW. I did not see any mention of built in pullups in the data sheet.
I wouldn't want a floating signal bouncing everywhere when the float sensor is open. What ohm pullups should i use? we are working at 5.1 v
im going to attach this anyways, nxp.com/docs/PCF8591 DATASHEET
Can you post a link to details of the float sensor? It sounds like you are connecting a digital sensor to an analog input. Why is that?
Yes im using it as digital input. I just happened to have some PCF8591's laying around so i decided to use them.
I think i need to pull the pin HIGH to 5v. but im afraid to pick the wrong value resistor and fry the chip. Will it hurt the PCF8591 if i short the analog output pin to 5V/ground?
Ok, but it seems a waste to use that chip. Perhaps if you share more details of your project we can suggest ways to save pins so that you will not need the PCF8591.
You can use any value resistor you like, there is no danger of frying the chip as long as you do not connect the resistor to a higher voltage than 5V. But a value which is too high (like 1M) might cause some false readings. A value which is too low (like 500R) will waste current. I would suggest 10K.
I need the analog input for 2 photoresistors. I still needed 2 inputs and an output so i think it worked out okay. Thankyou. i should not worry about shorting input to GND and ill use 10k for the pulls ups
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