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Quickstart

Five-minute hello-world: install, wire, read your first measurement, integrate Wh. If you've already read Hardware Setup for your host MCU, skip the wiring section.

Prerequisites

  • One rbAmp module (any tier — BASIC UI1 / STANDARD / PRO all work the same)
  • Any I2C-capable Arduino-supported board (Uno, ESP32, ESP8266, STM32duino, RP2040)
  • 4 wires: 3V3, GND, SDA, SCL between module and host
  • Arduino IDE 2.x (or Arduino CLI / PlatformIO)
  • A live AC circuit you can clamp the CT around (lamp, kettle, electric heater)

Step 1 — Install the library

Arduino IDE

Sketch → Include Library → Manage Libraries… → search RbAmp → Install.

Arduino CLI

sh
arduino-cli lib install RbAmp

PlatformIO

ini
[env:esp32dev]
platform   = espressif32
framework  = arduino
lib_deps   = rbamp/RbAmp@^1.0.0

Step 2 — Wire it up

rbAmp Host MCU
3V3 3.3 V supply
GND GND
SDA I2C SDA (Uno: A4 · ESP32: GPIO21 · ESP8266 D2 · STM32 Blue Pill PB7)
SCL I2C SCL (Uno: A5 · ESP32: GPIO22 · ESP8266 D1 · STM32 Blue Pill PB6)

If you're on ESP32, set the bus to 50 kHz in your sketch — SPEC §B.5 mandate against the PY32 v1.0 NACK pattern. Other hosts can run 100 kHz or 400 kHz freely.

Clamp the CT around one AC live conductor (not the entire flex with both live + neutral — that nets out to zero). The arrow on the clamp body should point into the load.

⚠ Do not wire the module's NRST pin to your host GPIO unless you read Hardware Setup first and accept the brick risk. Use dev.reset() instead.

Step 3 — First sketch

Create a new sketch (File → New) and paste:

cpp
#include <Wire.h>
#include <RbAmp.h>
RbAmp dev(Wire, 0x50);    // Wire bus, default slave address 0x50
void setup() {
    Serial.begin(115200);
    while (!Serial && millis() < 3000) { /* wait for USB-CDC on native ports */ }
    Wire.begin();
    // ESP32 only — uncomment for SPEC §B.5 compliance:
    // Wire.setClock(50000);
    dev.setLogStream(&Serial);   // prints library diagnostic messages
    Serial.println(F("Probing rbAmp..."));
    while (!dev.begin()) {
        Serial.print(F("begin() failed: "));
        Serial.println(RbAmp::errorString(dev.lastError()));
        delay(1000);
    }
    Serial.print(F("OK — firmware 0x"));
    Serial.print(dev.firmwareVersion(), HEX);
    Serial.print(F(", channels="));
    Serial.println(dev.channels());
}
void loop() {
    Serial.print(F("U=")); Serial.print(dev.readVoltage(), 1);
    Serial.print(F("V  P=")); Serial.print(dev.readPower(0), 1);
    Serial.print(F("W  PF=")); Serial.println(dev.readPowerFactor(0), 3);
    delay(1000);
}

Upload it. Open the Serial Monitor at 115200 baud. You should see:

plaintext
Probing rbAmp...
OK — firmware 0x1, channels=3
U=230.4V  P=+48.2W  PF=+0.972
U=230.1V  P=+48.1W  PF=+0.972
...

The channels=3 reading is the constructor's default ThreePhase hint — override it if you know your SKU is UI1 / UI2:

cpp
RbAmp dev(Wire, 0x50, RbAmpTopology::Single);     // for UI1 / I1 SKUs
RbAmp dev(Wire, 0x50, RbAmpTopology::SplitPhase); // for UI2 / I2 SKUs

Over-detection (3 hint on a UI1 module) is harmless — unused channels read 0.0 A and contribute 0 Wh.

Step 4 — Add energy metering

Modify loop() to use period metering + the built-in Wh accumulator:

cpp
void loop() {
    delay(60000);   // one minute period
    RbAmpPeriodSnapshot snap;
    if (!dev.readPeriodSnapshot(snap)) {
        Serial.print(F("snapshot: "));
        Serial.println(RbAmp::errorString(dev.lastError()));
        return;
    }
    Serial.print(F("avg_P=")); Serial.print(snap.avg_p[0], 2);
    Serial.print(F("W  Wh=")); Serial.print(dev.energy().wh(0), 4);
    Serial.print(F("  dt=")); Serial.print(snap.master_dt_ms); Serial.println(F("ms"));
}

The readPeriodSnapshot() call:

  1. Writes CMD_LATCH_PERIOD (closes the current measurement window).
  2. Waits 50 ms (SPEC §7 mandate for the firmware to finalize the snapshot).
  3. Checks REG_V03_PERIOD_VALID — returns false with lastError() == RB_ERR_STALE if the snapshot was stale.
  4. Reads avg_p[0..channels-1] + max_p + latch_ms.
  5. Computes master_dt_ms from millis() since the previous successful snapshot.
  6. Calls energy().tick() internally — dev.energy().wh(0) now reflects the running total.

Expected output (one line per minute, ~50 W load):

plaintext
avg_P=50.18W  Wh=0.8364  dt=60012ms
avg_P=50.21W  Wh=1.6735  dt=60005ms
avg_P=50.19W  Wh=2.5103  dt=60008ms
...

The master_dt_ms is the master's wall-clock interval between successful latches — authoritative for energy integration. The chip's latch_ms is diagnostic only (it can drift up to 20 % on PY32's uncalibrated LSI clock).

Step 5 — Configure the CT model

If your CT clamp is not the default SCT-013-30A, set the right model and persist to flash:

cpp
void setup() {
    // ...as above...
    while (!dev.begin()) { delay(1000); }
    // Set CT model — 1=5A, 2=10A, 3=30A (default), 4=50A, 5=100A.
    if (!dev.setCTModel(1)) {   // example: SCT-013-005
        Serial.print(F("setCTModel: "));
        Serial.println(RbAmp::errorString(dev.lastError()));
    }
    // Blocks ~700 ms for the flash erase + write. Done.
}

On v1.1 firmware this also triggers preset NF + GAIN auto-load. On v1.0 firmware, you'll additionally need to tune NF + GAIN per Sensor Selection.

What you've learned

  • The library wraps every SPEC-mandated protocol detail (50 ms settle, PERIOD_VALID check, retry, sanity filter, Wh integration) so your sketch doesn't deal with them.
  • dev.readPeriodSnapshot(snap) is the recommended entry point for any energy-metering use case.
  • dev.energy().wh(ch) returns the running per-channel Wh total — updated automatically on every successful snapshot.
  • dev.setCTModel(code) configures the CT clamp once at install time.

Next steps

Related — main rbAmp documentation

Source & issues: rb-amp/rbamp-arduino · this page in the repo: docs/05_quickstart.md

Prerequisites Step 1 Install the library Step 2 Wire it up Step 3 First sketch Step 4 Add energy metering Step 5 Configure the CT model What you've learned Next steps Related main rbAmp documentation