HM-10 Stand-Alone Remote Light Sensor Using The Built In ADC

Here we create a remote light sensor using a stand-alone HM-10 and a Light Dependent Resistor (LDR). The LDR is connected to peripheral HM-10 pin PIOB. Using MODE1 means we can read the value of PIOB from the Central HM-10 over the wireless connection.

HM-10 Set up

The two modules have been set to auto connect using AT+IMME1 and the Peripheral module is in MODE1.

Circuit

The Master or Central HM-10 is connected to an Arduino. The Peripheral or Slave HM-10 has an LDR connected to PIOB. I have the remote HM-10 powered from a bread board power adapter but you could also use a battery. The remote HM-10 has +5v on vcc and +3.3v going to the LDR.

Sketch

The sketch is very simple, it sends “AT+ADCB?” and gets the reply. “AT+ADCB?” requests the voltage on pin PIOB of the remote HM-10.

//  Sketch: HM-10_Example_04A_RemoteLightSensor
//
//  Master HM-10
//  Pins
//  BT VCC to Arduino 5V out. 
//  BT GND to GND
//  Arduino D8 (ASS RX) - BT TX no need voltage divider 
//  Arduino D9 (ASS TX) - BT RX through a voltage divider
//
//  Remote HM-10
//  HM-10 vcc to +5V
//  HM-10 GND to GND
//  HM-10 PIOB to LDR/CDS

 
#include 
AltSoftSerial BTSerial; 
 
char c=' ';
char reply[30];
int pos = 0;
 
void setup() 
{
    Serial.begin(9600);
    Serial.print("Sketch:   ");   Serial.println(__FILE__);
    Serial.print("Uploaded: ");   Serial.println(__DATE__);
    Serial.println(" ");

    Serial.println("The HM-10s should be set for auto connect");
    Serial.println("The remote HM-10 should be set for MODE1");
    
    BTSerial.begin(9600);  
    Serial.println("BTserial started at 9600");
    Serial.println(" ");
}
 
void loop()
{
    BTSerial.print("AT+ADCB?");
    delay(500);

    pos = 0;
    while ( BTSerial.available() )
    {
        c = BTSerial.read();
        reply[pos] = c;
        pos++;
    }
    reply[pos] = '\0';
    Serial.print("Reply = "); Serial.println(reply); 

    delay (3000);

}

I am simply displaying the results in the serial monitor but you could set up something like a flashing LED on the Arduino to warn you when a light turns on (or off).