HC-12 not sleeping

Other Hardware 3rd Party Boards
1

Hello all,
I am measuring the current to my HC-12 module and it is steady at 14-15 mA whether in sleep mode or not. I do get an "OK+SLEEP" response from the module so I believe it is receiving the command ok. I am sure it is something really simple but I can't quite spot it. Any help would be greatly appreciated. I can see a drop in current for a split second when I send the sleep command so I think it may be waking up immediately for some reason. Here is stripped-down version of my code:

#include <SoftwareSerial.h>

#define HC12_SET 5
#define HC12_TX 10
#define HC12_RX 11

SoftwareSerial HC12(HC12_TX, HC12_RX);

void HC12_Sleep()
{

	digitalWrite(HC12_SET, LOW);            // Enter command mode
 	delay(100);                             // Allow chip time to enter command mode
 	HC12.print("AT+SLEEP");             	// Send command
 	delay(200);                             // Wait for a response
  	digitalWrite(HC12_SET, HIGH);         // Exit command / enter transparent mode

}

void HC12_Wake()
{
	digitalWrite(HC12_SET, LOW);            // Enter command mode
 	delay(100);                             // Allow chip time to enter command mode
 	digitalWrite(HC12_SET, HIGH);         // Exit command mode
 	delay(100);                             // Delay before proceeding

}
void setup()
{

	pinMode(HC12_SET,OUTPUT);

	HC12.begin(9600);
	HC12_Sleep();
	HC12.end();

}


void loop()
{ 
	HC12.begin(9600);
	HC12_Sleep();
	HC12.end();

	
	delay(5000);
	return;
}
2

Why did you run a HC12.begin() and .end() in every loop cycle?

Also you never have to call return in the Arduino loop() function.

Try this code and measure the HC-12 current:

#include <SoftwareSerial.h>

#define HC12_SET 5
#define HC12_TX 10
#define HC12_RX 11

SoftwareSerial HC12(HC12_TX, HC12_RX);

void HC12_Sleep()
{

	digitalWrite(HC12_SET, LOW);            // Enter command mode
 	delay(100);                             // Allow chip time to enter command mode
 	HC12.print("AT+SLEEP");             	// Send command
 	delay(200);                             // Wait for a response
  	digitalWrite(HC12_SET, HIGH);         // Exit command / enter transparent mode

}
void setup()
{
	pinMode(HC12_SET,OUTPUT);

	HC12.begin(9600);
	HC12_Sleep();
	
}


void loop()
{  }
3

Try this

#include <SoftwareSerial.h>

#define HC12_SET 5
#define HC12_TX 10
#define HC12_RX 11

SoftwareSerial HC12(HC12_TX, HC12_RX);

void HC12_Sleep()
{

	digitalWrite(HC12_SET, LOW);            // Enter command mode
 	delay(100);                             // Allow chip time to enter command mode
 	HC12.print("AT+SLEEP");             	// Send command
 	delay(200);                             // Wait for a response
  	digitalWrite(HC12_SET, HIGH);         // Exit command / enter transparent mode

}

void HC12_Wake()
{
	digitalWrite(HC12_SET, LOW);            // Enter command mode
 	delay(100);                             // Allow chip time to enter command mode
 	digitalWrite(HC12_SET, HIGH);         // Exit command mode
 	delay(100);                             // Delay before proceeding

}
void setup()
{

	pinMode(HC12_SET,OUTPUT);

	HC12.begin(9600);
	//HC12_Sleep(); <-- delete this
	//HC12.end(); <-- delete this

}


void loop()
{ 
	//HC12.begin(9600); <-- delete this
	HC12_Sleep();
	//HC12.end(); <-- delete this
	
	delay(5000);
	//return; <-- delete this

    HC12_Wake();

    delay(5000);
}
4

Hey guys,
Thanks for your replies. I tried both very sketches and neither work. When I call sleep, the current drops to 0.05 mA for a split second, then goes right back to 15 mA. Very frustrating. Same result with three different modules. And when I check the return from AT+SLEEP I get the proper response so I know things are communicating.

I have a new HC-12 on order. Maybe I got a bad batch...but you know you are desperate when you are swapping hardware.

5

Please show you resulting code

6

Here it is. Can't get much simpler. I received a new HC12 today. Same result. Thanks alot for looking at this. It must be something very simple...

// HC-12_sleep.ino

#include <SoftwareSerial.h>


#define HC12_SET	5
#define HC12_TX	10
#define HC12_RX	11

SoftwareSerial HC12(HC12_TX, HC12_RX); // HC-12 TX Pin, HC-12 RX Pin


void HC12_Sleep()
{
	digitalWrite(HC12_SET, LOW);           
	delay(100);                         
 	HC12.print("AT+SLEEP");             	
 	delay(200);                            
  	digitalWrite(HC12_SET, HIGH);         

}

void HC12_Wake()
{
	digitalWrite(HC12_SET, LOW);           
 	delay(100);                        
 	digitalWrite(HC12_SET, HIGH);         
 	delay(100);                         

}
void setup()
{

	pinMode(HC12_SET,OUTPUT);


	HC12.begin(9600);
	HC12_Sleep();

}




void loop()
{ 
	HC12_Sleep();
	delay(3000);
	HC12_Wake();
	delay(3000);
	return;

}
7

You never have to call return in the Arduino loop() function.

As for code - try to add line feed after the command:

8

By "add a line feed" - I am guessing you meant to the SLEEP string as in "AT+SLEEP\n". That had no effect.
Removing the loop() return had no effect but that makes sense as the return in a void function in C is optional\implied.

I am really stumped. I will see if I can send AT commands directly from the serial monitor and see what that does.

9

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