UGE GP8212S 4–20 mA Current Loop Generator Module

Compact I²C-controlled analog output board based on the Linearin GP8212S-TC50-EW (15-bit DAC → industrial 0 / 4–20 mA current loop).

Open interactive BOM ↗ — browser BOM for soldering / identifying parts (do not use the GitHub .html file viewer).

Chip	GP8212S-TC50-EW (ESOP-8), 15-bit I²C
Output	0–25 mA full scale (typical with Rs = 100 Ω); use 4–20 mA for industrial loops
Interface	I²C address 0x58, logic 2.7–5.5 V (Arduino & ESP32 friendly)
Module power	5 V input → onboard MT3608 boost → ~12 V for the DAC
MCU examples	Arduino / ESP32 library in this repo; STM32 bit-bang reference included
Interactive BOM	Open in browser

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Buy

Item	Link
GP8212S chip only	uge-one.com — GP8212S-TC50-EW
Empty bare PCB	uge-one.com — PCB for I2C 4–20 mA generator
Interactive BOM	Open live BOM

Assembled modules: contact UGE Electronics.

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Repository layout

software/GP8212S/     Arduino & ESP32 library + examples
docs/                 GitHub Pages site + interactive BOM + images
hardware/             Link to the live BOM (GitHub code view cannot render HTML)
stm32_reference/      Original STM32F10x bit-bang I²C (MyI2C)

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Quick start (Arduino / ESP32)

1. Install the library

Option A — manual

1. Download this repository (Code → Download ZIP) or clone it.
2. Copy the folder software/GP8212S into your Arduino libraries directory:
   • Windows: Documents\Arduino\libraries\GP8212S
   • macOS: ~/Documents/Arduino/libraries/GP8212S
   • Linux: ~/Arduino/libraries/GP8212S
3. Restart the Arduino IDE.

Option B — ZIP

Sketch → Include Library → Add .ZIP Library… and select a ZIP that contains the GP8212S folder (with library.properties at its root).

2. Wire the module

Module	Arduino Uno / Nano	ESP32 (typical)
SDA	A4	GPIO 21
SCL	A5	GPIO 22
GND	GND	GND
5 V	5 V (powers MT3608 → ~12 V for the DAC)	5 V capable supply to module VIN

• Share GND between MCU and module.
• Do not feed the GP8212S chip VCC pin from USB 5 V directly — use the module’s 5 V input so the MT3608 can boost to ~12 V.
• I²C works at 3.3 V (ESP32) or 5 V (classic Arduino).

3. Minimal sketch

#include <Wire.h>
#include <GP8212S.h>

GP8212S dac;  // I2C 0x58, 25 mA full scale (Rs = 100 Ω)

void setup() {
  Serial.begin(115200);

#if defined(ESP32)
  if (dac.begin(21, 22) != 0) {   // SDA, SCL
#else
  if (dac.begin() != 0) {
#endif
    Serial.println("GP8212S not found");
    while (true) {}
  }

  dac.setCurrent_mA(12.0);     // milliamps
  // dac.setPercent4_20(50);   // 0–100% of 4–20 mA span
  // dac.setDAC(0x3D70);       // raw 15-bit code
}

void loop() {}

4. Examples

After install: File → Examples → GP8212S

Example	What it does
CurrentSweep	Sweeps 4 → 20 → 4 mA
SetAndStore	Set mA from Serial; optional NVM store()
Calibrate4_20	Interactive two-point calibration with a meter

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API overview

Method	Description
begin(sda, scl, freq)	Init I²C and probe (returns 0 on ACK)
setCurrent_mA(mA)	Output current in mA (0 … full scale)
setPercent4_20(pct)	0% → 4 mA, 100% → 20 mA
setDAC(code)	Raw 15-bit code 0 … 0x7FFF
calibrate4_20(dac4, dac20)	Use measured codes for accurate 4–20 mA
store(sda, scl)	Save last DAC value in chip NVM (survives power-off)

Ideal codes with Rs = 100 Ω (0–25 mA full scale):

Current	Approx. DAC
4 mA	5243 (0x147A)
12 mA	15728 (0x3D70)
20 mA	26214 (0x6666)
25 mA	32767 (0x7FFF)

Datasheet: IOUT = (2.5 V / Rs) × (DATA / 0x7FFF).

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Calibration (recommended)

At ~12 V loop supply (MT3608), use a 220–330 Ω load (compliance is lower than at 24 V).

1. Power the module from 5 V, connect I²C, load on IOUT, DMM in series (mA) or measure V / R across the load.
2. Run Calibrate4_20, open Serial Monitor @ 115200.
3. Trim to 4.000 mA → send s4.
4. Trim to 20.000 mA → send s20.
5. Send apply and paste the printed line into your sketch:

dac.calibrate4_20(/* your 4 mA code */, /* your 20 mA code */);

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Hardware & soldering

Interactive BOM (opens in the browser)

GitHub’s file viewer only shows HTML source. Use one of these instead:

Live page (recommended)	Open interactive BOM
Docs home	ugeelectronics.github.io/…/
Offline	Download docs/GP8212SBOM.html and double-click it

First-time Pages setup (repo admins) — required once:

1. Open Settings → Pages
2. Under Build and deployment → Source, choose Deploy from a branch
3. Branch: main, folder: /docs → Save
4. Wait about a minute, then open the live BOM link above.

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STM32 reference

stm32_reference/MyI2C.c is the original STM32F10x open-drain bit-bang I²C layer (no high-level DAC API). The Arduino library replaces that with Wire and implements the GP8212S register write / store sequence.

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Notes & limits

• Default I²C address: 0x58.
• Chip VCC range per datasheet: 9–36 V; this module uses ~12 V from MT3608 after 5 V input.
• Max load resistance shrinks at 12 V vs 24 V — keep calibration / field loads in the ~220–330 Ω range unless you raise the boost voltage within safe design limits.
• There is no official Arduino library named GP8212S from the chip vendor; DFRobot’s GP8XXX covers related parts (e.g. GP8211S / GP8302) but not this module. Use UGE GP8212S here.

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License

MIT — see LICENSE.
© 2026 UGE Electronics — uge-one.com