Y Forum

[alex]

Hello,
I have some questions regarding the btm-180 bluetooth module.Im new to the field and im trying to understand how it works.First i have searched the internet and i`ve found different opinions regarding the connection of the module to a microcontroller.Im using a ATMega16 and through bluetooth i want to send messages from the computer to the board let say display it on a LCD and from the board to the pc .I have a temperature sensor(lm35) and on a certain command i want to receive from the board the temperature (this for the transmission part). On some sites i saw that they connected the UART_TX, UART_RX, UART_CTS , UART_RTS VDD and GND but this for another type of bluetooth module.I want to make my module to work both as a receiver and a transmitter so do i really need the handshaking assured by CTS and RTS?Or i will connect the UART_TX and UART_RX of the module directly to the microcontroller TxD and RxD?
Another question is how to make my module discoverable since i dont find a complete datasheet with the AT commands.Could you help me please with some guidelines or a schematics in eagle?Thank you very much

[Florin]

Hi Alex,
I'm currently using the BTM-180 module with just the RX and TX lines connected to a PIC micro. At first it worked with just 3.3V and because of the datasheet which btw is a mess I thought that is the correct voltage. But several days ago mysteriously my module stopped working. I tried to up the voltage up to aprox 3.7 V and surprise it started working again. Now I'm powering the module with 5V and it works ok.

Regarding your question about the "discoverable mode" it's that way by default so you should be able to discover it out of the box. I'm attaching the list of AT commands supported by this module, but note the way you send the commands is somewhat different that with other modules. You have to send one char at a time like this :

Code: Select all

//command mode
putsUART2("+");
DelayMs(25);
putsUART2("+");
DelayMs(25);
putsUART2("+");
DelayMs(25);
putcUART2(0x0D);
DelayMs(30);

//change name
putsUART2("A");
DelayMs(25);
putsUART2("T");
DelayMs(25);
putsUART2("N");
DelayMs(25);
putsUART2("=");
DelayMs(25);
putsUART2("p");
DelayMs(25);
putsUART2("l");
DelayMs(25);
putsUART2("a");
DelayMs(25);
putsUART2("t");
DelayMs(25);
putsUART2("f");
DelayMs(25);
putsUART2("o");
DelayMs(25);
putsUART2("r");
DelayMs(25);
putsUART2("m");
DelayMs(25);
putsUART2("a");
DelayMs(25);
putcUART2(0x0D);
DelayMs(30);


As you can see you have to wait 25ms after each letter and 30 ms after 0x0D (carriage return) which must be added to the end of every command. Try this and let me know how it goes .


Florin