Learning Bluetooth LE with the BLE2 Click


Playing with the Bluetooth Low Energy Click board (BLE2 based on the RN4020) on a Curiosity board is a fun way to get acquainted with this technology. My first humble step was to get the simplest example offered in the RN4020 PICTail (one of the earliest demo boards available for evaluation of the little radio module) user guide and port it over with minor modifications to my new hardware setup.

Using the MCC, I performed the following simple initialisations:

  • GPIOs: CMD on RC5 (out), WAKE_SW on RA4(out), CONN on RC2 (in)
  • TMR2: 4ms period
  • ADC:  channel POT on RC0, left aligned, ~40k smps
  • EUSART: Asynchronous 115,200 baud, 8-bit, none, stdio redirect

And voila’ the application was created and ready for me to fill in the main() function.

I added an initialisation of the RN4020 module:

 // initialize RN4020
 WAKE_SW_SetHigh(); // enter command mode
 sendCMD( "SF,1");        // factory reset
 sendCMD( "SS,C0000000"); // enable DeviceInformation and batter 
 sendCMD( "SR,00000000"); // act as a peripheral
 sendCMD( "S-,Curiosity");// change name
 sendCMD( "R,1");         // reboot with new settings
 __delay_ms( cmdLONGDELAY); // wait for CMD prompt
 sendCMD( "A");           // start advertising
 while( !CONN_GetValue());// wait for a connection

Followed by  a very simple main loop:

   while (1) {
        uint8_t time;
        // time is measured in multiples of TMR2 period (4ms)
        if ( TMR2_HasOverflowOccured()) { 
        if ( time >= 50)   // 200ms
            uint8_t battery =  ADC1_GetConversion( POT)>>9;
            time = 0;
            // update the battery level characteristic
            printf( "SHW,0018,%02x\n", 
                    (battery>100)? 100: battery); 

Notice how this demo does not use the MLDP mode – which emulates a sort of Serial profile similar to the (RN41) Standard Bluetooth module – which would have felt like cheating here. (See my previous project using the RN41 Bluetooth Click [link])

My intention is to learn how to define GATT Services and Characteristics and make full use of the BLE proper features.

You will find the new BLE-Battery project added to the Curiosity Rocket repository on GitHub [link].

Also I can strongly recommend the following applications, for iPhone and iPad users:

For Android smart phone, users:  Android App Demo

To be continued…

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