Propeller Board using a flowmeter

Jkane

Hello,

I have a question, I have a flowmeter, that counts pulses (highs and lows), the faster the pulses come the more liquid is moving thru the flowmeter, from there I just ouput a number.

but my question is that the flow meter runs from 4.5Volts to 24volts, so I was going to use basic stamp version that runs at 5 volts but I really want to use the properller which lives in the 3.3 volt world, and all my projects use propeller.

so it there a way to use the propeller to read pulses in a 4.5volt world.

I'm thinking that a resister in series from the 4.5 signal should protect the 3.3 pin being used on the propeller.

regards

Jeff

JonnyMac

If the output is driven high then you can use a 3.3K (for 5V output) series resistor. Check your sensor, many are configured as open-collector which allows their connection to devices of different voltages. If the output is in fact open collector, connect a 10K pull-up to the a pin on the Propeller, and connect the open-collector output to that as well. You must connect ground from the sensor to ground on your Propeller.

If you have an open-collector sensor the leading edges of the pulses will go low. You can easily measure the falling-edge to falling edge timing to determine flow rate.

Jkane

JonnyMac wrote: »

If the output is driven high then you can use a 3.3K (for 5V output) series resistor. Check your sensor, many are configured as open-collector which allows their connection to devices of different voltages. If the output is in fact open collector, connect a 10K pull-up to the a pin on the Propeller, and connect the open-collector output to that as well. You must connect ground from the sensor to ground on your Propeller.

If you have an open-collector sensor the leading edges of the pulses will go low. You can easily measure the falling-edge to falling edge timing to determine flow rate.

Thanks, looks like the 3.3K should work and yes, common ground for both propeller and meter.

the data on the sensor signal out is:

Output:Signal: 4.5 VDC to 24 VDC Pulse (sourcing) Pulse Rate Dependent on flow rate, port size and range

Output Signal for the RFO Types is an on/off pulse of the DC voltage supplied to the unit, it is compatiable with all digital logic families. Input voltage range is 4.5 to 24 VDC. Frequency of the output pulse is porportional to the flow rate and ranges from approximately 15 Hz at low flow to 225 Hz at high flow.

The meter has three wires, Red +VDC, Black = Ground and White = Signal Output.

regards

Jeff