Bluetooth LE: Using CC-41A (HM-10 Clone)

I bought some Bluetooth Low Energy 4.0 HM-10 modules online, turned out to be the cheaper chinese CC-41A clone modules. They are similar to HM-10 and at this point I can only say that CC-41A has limited commands supported, though suffices my requirements. I was able to set it to iBeacon mode too (later on that).

I also learned that

• CC-41A commands are case insensitive, so ‘AT’ and ‘at’ both work!

• CC-41A commands needs to be terminated with \r \n

• CC-41A commands does not entertain ‘?’

• CC-41A default boots to slave mode (Role0)

• CC-41A command – AT+HELP prints all supported commands in that mode

In master role (AT+ROLE1), there is a different set of supported commands

• AT+INQ, runs a scan and lists all devices found (It only searched for CC-41A devices for me)

• AT+CONNn (n is device number from INQ), connects to given device

• Once connected, all commands are passed to remtoe device, and I am not sure how to disconnect from a connected device.

• I don’t know yet how to make CC-41A auto connect to last connected device by default

I tried to update firmware and ended up burning one board, thus I would recommend not to go that direction unless extremely necessary. If you are adventurous, install HM-10 firmware –

• CCLoader Sketch for Arduino

• Windows binary

• HM-10 Original firmware

http://forum.arduino.cc/index.php?topic=393655

Code for Master Controller

#include <SoftwareSerial.h>
 
SoftwareSerial BTSerial(4, 5);
 
void setup() {
   Serial.begin(9600);
   BTSerial.begin(9600);
   BTSerial.write("AT+DEFAULT\r\n");
   BTSerial.write("AT+RESET\r\n");
   BTSerial.write("AT+NAME=Controller\r\n");
   BTSerial.write("AT+ROLE1\r\n");
   BTSerial.write("AT+TYPE1"); //Simple pairing
}
 
void loop()
{
   if (BTSerial.available())
       Serial.write(BTSerial.read());
   if (Serial.available())
       BTSerial.write(Serial.read());
}

Switch to Role1 – AT+ROLE1

• AT+HELP will now have different set of commands

• AT+INQ will search for devices

• AT+SHOW fetches search result from cache

• AT+CONN[n] connects to the device by index

Code for Slave Device

#include <SoftwareSerial.h>
 
SoftwareSerial BTSerial(4, 5);
char cmd[32] = {0};
 
void setup() {
   Serial.begin(9600);
   BTSerial.begin(9600);
   BTSerial.write("AT+NAME=Remote\r\n");
   BTSerial.write("AT+TYPE1"); //Simple pairing
}
 
void loop()
{
   static int iter = 0;
   if (BTSerial.available())
   {
       cmd[iter] = BTSerial.read();
 
       //if CRLF (CC41A EOM)
       if((cmd[iter] == 10) && (cmd[iter-1]==13))
       {
   
           Serial.println(cmd);             //dump to serial console
 
           BTSerial.write("Command executed:");
           BTSerial.write(cmd); BTSerial.write("\n");
     } else {
   
     }
   }
   
   if(Serial.available()){
     BTSerial.write(Serial.read());
   }
}