SparkFun will be closed Nov 26th and 27th for the Thanksgiving holiday. Orders placed after 2:00pm MT on the 25th will ship out Monday the 30th.



Member Since: September 23, 2010

Country: United States


Ham Radio Operator, Electronics Tech, Network Engineer, Programmer. http://arduinotronics.blogspot.com

  • What is the proper syntax for saving the scale output in a variable?

    float value;

    Serial.print(scale.getGram(), 1); <—– WORKS

    value = (scale.getGram(), 1) ;

    Serial.println(value); <—– NO GOOD! DISPLAYS: “1.00”

    value = (scale.getGram(), 2) ;

    Serial.println(value); <—– NO GOOD! DISPLAYS: “2.00”

  • The data sheet claims one trigger for every revolution of the anemometer. I have verified on 2 units it’s two triggers per revolution. working anemometer code posted at http://arduinotronics.blogspot.com/2015/08/measuring-wind-speed-with-arduino.html

  • “ A wind speed of 1.492 MPH produces a switch closure once per second.” Can’t be right. That would equal a 8.363" diameter anemometer. Correct me if I’m wrong, the diameter is 5.5", so 60 rpm (1 RPS) = a wind speed of 0.98125 MPH.

  • Momentarily connects A5 to ground.

  • OK, so even though the sketch says a 1k Ohm resistor should be added (and mixes up rx and tx), the data sheet says this unit is 5v friendly. I have both the enroll and the ID sample sketches operating fine, with no resistor. Pin 1 on the fingerprint scanner (black wire) is TX and connects to RX on the Arduino (Pin 4 in sample sketch), and Pin 2 (RX) on the fingerprint scanner connects to pin 5 (TX) on the Arduino. Pin 3 on the Finger print scanner connects to Arduino Gnd, and Pin 4 to 3.3v or 5v. I’m using 5v on the UNO.


  • OK, cable arrived, but reading the sample sketches, it appears a 1k Ohm resistor is needed because this fingerprint unit is 3v logic. I feel that this should be prominently mentioned in the part description!

  • The S&H costs more than the cable. Will have to wait for next order.

  • Wouldn’t 3.3 - 6 mean any voltage from 3.3v through 6v ……

  • I suggest just include the cable, and up the price of the scanner $1.50 It’s not like it can be used without it.

  • My fingerprint scanner did not come with a cable. It’s unusable without one. For a >$30 sensor, I expect better. I suggest you ship a cable with these in the future. What cable do I need to order?