I have a HMC5883L and its pins are labeled SDA, SCL, DRDY, VIN, and GND. SO I am following this tutorial and it has a VCC pin but mine doesn't have it so I was wondering if VIN is the same as VCC because VIN looks the closest to VCC.

  • \$\begingroup\$ Have you tried looking up the datasheet on the internet (I found one in a few seconds Googling), and comparing that with the device you have? The ones I see have 16 pins, one of which is VDD, but no VIN. \$\endgroup\$
    – Simon B
    Sep 10, 2016 at 21:08
  • \$\begingroup\$ Find the VDD pin on the chip, and (with the power off) do a continuity test between there and the VIN pin on the module. Not every module designer will include a voltage regulator, but if they did, this sort of VDD vs VIN naming difference is exactly what would be used to differentiate the chip power pin from the module pin that supplies the regulator that powers the chip. \$\endgroup\$
    – Ben Voigt
    Sep 11, 2016 at 0:18
  • \$\begingroup\$ @BenVoigt - Your probing plan is a good one. Too bad the LPCC chip is very difficult to probe. I would suggest just applying a DC voltage between +2.2 to +3.6 to "Vin". If the is a regulator on-board, no harm will result. If it is a direct run with no regulator, the magnetometer will come to life. \$\endgroup\$
    – glen_geek
    Sep 11, 2016 at 2:11

1 Answer 1


Nomenclature is always a problem, so sometimes one has to make a good guess. That HMC5883L requires a DC supply voltage. Does your module seem to have an on-board battery?...no?...then the DC supply likely comes from an external source. The pin labeled "GND" is required by the serial link (SDA,SCL) for data communication, but it can also be the ground return of this external source.
Another clue comes from the similarity of pin nomenclature to your tutorial photo. The only one that differs is "VIN" vs. "Vcc". You are thinking intelligently in relating these two.
Since power is likely supplied from an external source to this module, it is reasonable to say that this is an input pin. It inputs voltage to the module. Silk-screen labels must be short, so these cryptic labels are ubiquitous.
Some more info on "Vcc":What is the difference between \$V_{CC}\$, \$V_{DD}\$, \$V_{EE}\$, \$V_{SS}\$


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