# Calibration of the sensor HSTS016L range 100A **URL:** \ **Category:** IoTaWatt\ **Created:** [26 January 2025 11:25 UTC](https://community.openenergymonitor.org/t/calibration-of-the-sensor-hsts016l-range-100a/27827 "2025-01-26T11:25:03Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Imenn](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/i/43a26b/32.png) [@Imenn](https://community.openenergymonitor.org/u/Imenn)\ **Post date:** [26 January 2025 11:25 UTC](https://community.openenergymonitor.org/t/calibration-of-the-sensor-hsts016l-range-100a/27827/1 "2025-01-26T11:25:03Z")
Hey community, I am using the HSTS016, range 100A, I am trying to calibrate it using an ESP32 in order to measure DC current, the problem is whatever I do to make it work it gives me values like literally non sense. Another thing, I cannot exactly understand the role of the Vref pin, like trying to find something useful in the datasheet but I find nothing. Please, if anyone worked with it before, tell me. Thank you, ---
**Author:** ![Robert.Wall](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/robert.wall/32/38246_2.png) [@Robert.Wall](https://community.openenergymonitor.org/u/Robert.Wall)\ **Post date:** [26 January 2025 15:56 UTC](https://community.openenergymonitor.org/t/calibration-of-the-sensor-hsts016l-range-100a/27827/2 "2025-01-26T15:56:11Z")
Welcome, @Imenn , to the OEM forum. I see you have tagged your question Iotawatt. Do you mean you want to use the current transformer with an Iotawart? Unfortunately, very few people here know anything about this device. I suggest you try asking at [https://community.iotawatt.com](https://community.iotawatt.com) _[Edit]_ I’d found a data sheet that described the Hall effect device as a current transformer - hence @Imenn’s note to that effect. ---
**Author:** ![Imenn](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/i/43a26b/32.png) [@Imenn](https://community.openenergymonitor.org/u/Imenn)\ **Post date:** [26 January 2025 16:19 UTC](https://community.openenergymonitor.org/t/calibration-of-the-sensor-hsts016l-range-100a/27827/3 "2025-01-26T16:19:03Z")
Thank you so much for your help. ---
**Author:** ![Imenn](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/i/43a26b/32.png) [@Imenn](https://community.openenergymonitor.org/u/Imenn)\ **Post date:** [26 January 2025 16:19 UTC](https://community.openenergymonitor.org/t/calibration-of-the-sensor-hsts016l-range-100a/27827/4 "2025-01-26T16:19:42Z")
Actually, the HSTS016L is a hall effect sensor not a current transformer sensor, so it measures both AC and DC ---
**Author:** ![Robert.Wall](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/robert.wall/32/38246_2.png) [@Robert.Wall](https://community.openenergymonitor.org/u/Robert.Wall)\ **Post date:** [26 January 2025 16:49 UTC](https://community.openenergymonitor.org/t/calibration-of-the-sensor-hsts016l-range-100a/27827/5 "2025-01-26T16:49:34Z")
> [@Imenn](#): > > HSTS016L I see what went wrong. Google returned the wrong data sheet and called it a current **transformer**. It is not. Now I see also what you mean by Vref - it is not the ESP32’s pin, You connect a stable and accurate 5 V power supply between 5V and GND, and the output will be at 2.5 V ± 0.625 V 15 mV with no current flowing. You will need to measure, but I _think_ Vref will be at the same d.c. voltage, that is, you can use Vref and the output to feed into a differential amplifier, to remove the effect of the ± 0.625 V 15 mV error. If this does not appear to be the case, leave it not connected. [This data sheet](https://cdn.shopifycdn.net/s/files/1/2723/6858/files/HSTS016L_2.5V_0.625V_5V__1_c1bbdd67-912c-4dbd-91c0-aa8bca399eda_2048x2048.jpg?v=1669012946:) seems to indicate the same thing: ![image](https://community.openenergymonitor.org/uploads/default/original/3X/4/7/470c0d373d336adf1228f896324448edf07db5bb.png) This also gives the calibration equation. ![image](https://community.openenergymonitor.org/uploads/default/original/3X/c/9/c983f2a39c730727b25b180b8fc0a843fb12bb51.png) ---
**Author:** ![awjlogan](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/a/9e8a1a/32.png) [@awjlogan](https://community.openenergymonitor.org/u/awjlogan)\ **Post date:** [27 January 2025 12:24 UTC](https://community.openenergymonitor.org/t/calibration-of-the-sensor-hsts016l-range-100a/27827/6 "2025-01-27T12:24:07Z")
> [@Robert.Wall](#): > > to remove the effect of the ± 0.625 V error Just a nit, but the ±625 mV is the output, not the error. The V\_REF pin can be used to subtract out the ~2.5 V bias correctly, which you have [alluded to in the past](https://community.openenergymonitor.org/t/calibration-value-in-case-of-hall-effect-sensor-with-voltage-output/19406/2). As is typical, the datasheet is terrible but the reference pin is described across a few implementations. ---
**Author:** ![Robert.Wall](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/robert.wall/32/38246_2.png) [@Robert.Wall](https://community.openenergymonitor.org/u/Robert.Wall)\ **Post date:** [27 January 2025 12:35 UTC](https://community.openenergymonitor.org/t/calibration-of-the-sensor-hsts016l-range-100a/27827/7 "2025-01-27T12:35:05Z")
> [@awjlogan](#): > > As is typical, the datasheet is terrible Agreed - the error is 15 mV. But the first data sheet I looked at was even worse - that’s where the 625 mV read as if it was the offset bias error.