Measuring the flow rate of a pump

[medwatt]

Hello,
I have a micro-pump and whenever the voltage applied is increased, water pumps out faster. I want to write a software that could tell me what voltage I'm using so that I can calculate the frequency.
I have a prior understanding of how to use the LTP port (parallel) of the computer using the 8 data lines but since any voltage > 0 can create a logic 1 on the data line, then there seem to be no way to detect changes.
If somebody has any idea on how to calculate the flow rate using the computer I'll be grateful.

 

[BradtheRad]

It sounds like you want a voltage monitor with analog-to-digital conversion ( ADC ).

Eight bits will give you a range of 256 different volt levels, from 0 to max (whatever you want to call max).

There are IC's to do this. It outputs a binary number through 8 pins. You would need an IC that sends 5V from the output pins. You would send it through a parallel port into your computer (since you say you're experienced with that method).

If you need speed then you would use 8 lines in parallel. However if you can take your time, then consider simple serial communication (via parallel port or USB). There may be an ADC IC which will fit the purpose.

Thinking about it further...

1.
Does your computer have a joystick input? It goes to an internal A-to-D converter. It updates many times per second. You can read the value using a line or two of code. At least it was that easy on the VIC-20 and COmmodore 64. :^)

2.
A DC motor often produces noise at its supply wires. You may need to filter the supply to obtain a stable voltage to feed to the ADC.

3.
The relationship between voltage and motor speed is close to linear, but not exactly linear. So you may decide you want to monitor motor frequency directly. Once you figure out the best way to count motor revolutions ( or commutations, etc.). Then you count them per time interval of your choosing. Send the value into your computer.