Anemometer/ Frequency Counter
Posted: 20 Apr 2019, 18:54
An electronic anemometer for windspeed quite often applies a 4cup-rotator with a contact-closure/revolution between it's interface-wire_A and interface-wire_B.
Cleaning junk, as 'left-over' found such a device (without any documentation), and that invites for experimentation .....
Digital interface
Connected the device with wire_A to port D4 of the WEMOS_ESP8266 (with internal pullup resistor+LED), and wire_B to GND.
At port D4 now a pulse-train appears with interval/frequency as function of windspeed hopping between VCC=3V and GND:
The LED pulses, and (under setting 'Pulse Counter / Delta') the 3 counters increment => interface function is OK!
Analogue interface
At wire_A connected parallel a very basic signal-integrating circuit to feed the ADC at port A0:
- using D4 as 'source' for the anemometer, the voltage from the anemometer will be never higher than the input-range for port A0
- a small condensator C1 for galvanic separation from port D4 and to provide pulse-signals at the edges of the pulse-train
- C1 through a diode feeding positive pulses to a bigger electrolite condensator C2 which has other side at GND
- the + of C2 is connected to A0 [perhaps a parallel resistor to GND may be useful for quicker discharge of C2]
The output of the circuit and the reading by the ADC show variation as function of windspeed => basic interface function is present!
Alignment/Calibration
Have 2 'real' meteo-anemometers, and therefore reference-info should not be a problem.
Real calibration may be a challenge, but some alignment of this setup would be nice.
Using 'formula' and/or 'rules' that must be achievable in the ESP8266 itself [I am using ESPEasy R147 at this (also left-over) WEMOS-board].
The A0-interface is the least complicated:
- just comparison of the analogue readout at A0 vs. the references, and deduct a calibration-factor as multiplier for %value% from A0.
The D4-interface is a questionmark:
- first need to get from the counter-data, either Pulsewidth-data PW, or Frequency-data F.
Starts with the question: what is represented by "Count/Time/Time"? No description in the Wiki!
- once found, then also just a matter by comparison of finding the suitable calibration-factor
But what is simplest method with 'formula' and/or 'rules' to get PW or F?
Examples not found by search at this Forum.
Somebody having a proven example?
Cleaning junk, as 'left-over' found such a device (without any documentation), and that invites for experimentation .....
Digital interface
Connected the device with wire_A to port D4 of the WEMOS_ESP8266 (with internal pullup resistor+LED), and wire_B to GND.
At port D4 now a pulse-train appears with interval/frequency as function of windspeed hopping between VCC=3V and GND:
The LED pulses, and (under setting 'Pulse Counter / Delta') the 3 counters increment => interface function is OK!
Analogue interface
At wire_A connected parallel a very basic signal-integrating circuit to feed the ADC at port A0:
- using D4 as 'source' for the anemometer, the voltage from the anemometer will be never higher than the input-range for port A0
- a small condensator C1 for galvanic separation from port D4 and to provide pulse-signals at the edges of the pulse-train
- C1 through a diode feeding positive pulses to a bigger electrolite condensator C2 which has other side at GND
- the + of C2 is connected to A0 [perhaps a parallel resistor to GND may be useful for quicker discharge of C2]
The output of the circuit and the reading by the ADC show variation as function of windspeed => basic interface function is present!
Alignment/Calibration
Have 2 'real' meteo-anemometers, and therefore reference-info should not be a problem.
Real calibration may be a challenge, but some alignment of this setup would be nice.
Using 'formula' and/or 'rules' that must be achievable in the ESP8266 itself [I am using ESPEasy R147 at this (also left-over) WEMOS-board].
The A0-interface is the least complicated:
- just comparison of the analogue readout at A0 vs. the references, and deduct a calibration-factor as multiplier for %value% from A0.
The D4-interface is a questionmark:
- first need to get from the counter-data, either Pulsewidth-data PW, or Frequency-data F.
Starts with the question: what is represented by "Count/Time/Time"? No description in the Wiki!
- once found, then also just a matter by comparison of finding the suitable calibration-factor
But what is simplest method with 'formula' and/or 'rules' to get PW or F?
Examples not found by search at this Forum.
Somebody having a proven example?