HM-10 returns Euro symbol

Question

I am working with HM-10 copy CC4A-1 module. I connected it with Arduino Uno R3 after struggling a lot it got connected. I performed some AT Commands using Arduino Serial Monitor suddenly it stops working after executing AT+RENEW command. I also tried to perform AT+BAUD command but it returned error before executing AT+RENEW.

This is the output of Arduino Serial Monitor while sending data from HMBLE Terminal Android Application

#include <SoftwareSerial.h>

SoftwareSerial BTSerial(2, 3); //RX|TX


void setup(){
  Serial.begin(9600);
  BTSerial.begin(9600); // default baud rate
  while(!Serial); //if it is an Arduino Micro
  Serial.println("AT commands: ");
}

void loop(){
  //read from the HM-10 and print in the Serial
  if(BTSerial.available())
    Serial.write(BTSerial.read());

  //read from the Serial and print to the HM-10
  if(Serial.available())
    BTSerial.write(Serial.read());
}

This is what is sent from Android Application

C. Thomas Brittain C. Thomas Brittain · Accepted Answer · 2016-07-15T17:06:55

Taking a look at the serial output, I would guess the baud rate didn't change whenever you sent the "AT+RENEW" command. The reason I suspect this is by looking at the binary equivalent of "€", which is "10000000". UART data is sent active low, so it looks to be detecting the beginning of a byte, however, the timing of the rest of the high-low signals is wrong. I would try connecting the module at whatever baud rate you had it set at before the AT+RENEW command.

The official HM-10 behavior is the module should return to a baud rate of 9600. However, I've noticed occasionally it needs to be reset by powering it off, then on. Or, sending "AT+RESET".

That being said, if it is an HM-10 clone, who knows what's really going on in the firmware.

HM-10 returns Euro symbol

2 Answers