====== LamaPLC: Allegro ACS758 Hall-effect linear current sensors ======
{{ :sensor:cjmcu_758_1.png?180|Allegro ACS758 Hall-effect linear current sensor}}
The provided part numbers refer to specific models within the **Allegro ACS758 series** of Hall-effect linear current sensor integrated circuits (ICs), which primarily differ in their current-sensing range, sensitivity, and operating temperature range.

^Part Number^Current Range^Sensitivity (Typ.)^Operating Temp. Range|
^ACS758LCB-050B (CJMCU-758)|±50 Amps|40 mV/A|–40 to 150 °C|
^ACS758LCB-100B|±100 Amps|20 mV/A|–40 to 150 °C|
^ACS758KCB-150B|±150 Amps|13.3 mV/A|–40 to 125 °C|
^ACS758ECB-200B|±200 Amps|10 mV/A|–40 to 85 °C|

  * **Supply Voltage:** 3.0 to 5.5 V.
  * **Internal Conductor Resistance:** Ultra-low 100 µΩ, providing minimal power loss.
  * **Bandwidth:** Typically 120 kHz.
  * **Zero Current Output:** For these bidirectional ("B") models with a 5V VCC, the output voltage is typically VCC/2 (2.5V) when no current is flowing. 

==== CJMCU-758 Pinout ====
{{ :sensor:cjmcu_758_2.png?180|Allegro ACS758 Hall-effect linear current sensor}}
**Low power**

  * **VCC:** Power supply input (3.0V to 5.5V).
  * **GND:** Ground connection.
  * **OU1:** Direct analog signal from the sensor.
  * **OU2:** Buffered signal through an onboard op-amp (often a Texas Instruments LM358 or similar) to reduce noise and drive longer cables.

**Power path**

  * **IP+:** Current input.
  * **IP-:** Current output.

**Directionality:** For bidirectional ("B") models, current can flow in either direction. For unidirectional ("U") models, current must flow from IP+ to IP- for a positive voltage increase. 

{{page>:tarhal}}

==== Arduino code ====
This code reads a bidirectional sensor (such as the models you listed) and computes the DC current. It assumes a 5V Arduino and that the sensor is powered by 5V.

Select the //mVperAmp// value based on your specific ACS758 model: 
  * 050B: 40 mV/A
  * 100B: 20 mV/A
  * 150B: 13.3 mV/A
  * 200B: 10 mV/A

<code c>
const int sensorPin = A0;      // Pin connected to CJMCU-758 OUT
int mVperAmp = 40;             // Change to 20, 13.3, or 10 based on model
int ACSoffset = 2500;          // 2.5V (VCC/2) is the 0A midpoint for bidirectional sensors

void setup() {
  Serial.begin(9600);
}

void loop() {
  // 1. Read raw ADC value (0-1023)
  int rawValue = analogRead(sensorPin);
  
  // 2. Convert raw value to voltage in mV
  // 5000mV / 1024 ADC steps = 4.88mV per step
  double voltage = (rawValue / 1023.0) * 5000; 

  // 3. Subtract offset and divide by sensitivity to get Amps
  double current = (voltage - ACSoffset) / mVperAmp;

  Serial.print("Raw: "); Serial.print(rawValue);
  Serial.print(" | Voltage(mV): "); Serial.print(voltage);
  Serial.print(" | Current(A): "); Serial.println(current, 2);

  delay(500);
}

</code>

**Key Considerations**

  * **Calibration:** The quiescent offset (voltage at 0 Amps) is theoretically 2500 mV but often varies slightly due to power supply noise or stray magnetic fields. Measure the voltage at 0 A, and update the ACSoffset in your code for improved accuracy.
  * **3.3V Microcontrollers:** If using an ESP32 or Arduino Due, you must use a voltage divider on the output to drop it below 3.3V, or use a 3.3V reference in your calculations (the sensitivity will also be lower).
  * **Averaging:** To reduce jitter, take 10–100 samples in your loop and compute the mean.

===== CJMCU topics on lamaPLC =====
{{topic>cjmcu}}
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{{tag>CJMCU CJMCU-758 ACS758 ACS758LCB-050B ACS758LCB-100B ACS758KCB-150B ACS758ECB-200B Hall-effect current sensor analog arduino code}}

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