Writting string in à BLE caractéristiques using CurieBLE lib

Projects Programming
1

Hello everyone,

I encounter a problem on an Arduino 101 communicating with a smartphone application, over BLE with CurieBLE library. I'm using several Services and typed Characteristics sucessfully, but for one of them, I need to exchange a data string (array of char) in both direction.

I could find how to write (from Arduino side) using the "BLECharacteristic()" method without type declaration, and adding a lenght parameter. Then I write using "setValue()" specifiyng the lenght. That is Ok.

But I tried several similar methods to perform the opposite operation : Reading a string from the Characteristic.... I couldn't find any solution to be able to compile without any error. I tried severai type declarations, pointer, ... nothing is right !

My problem is on Arduino side, not with smartphone application.

Do someone already experiment this and have the solution ??

Some code extracts :
unsigned char MyString[16] ;
BLECharacteristic MyChar("xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx", BLERead | BLEWrite,16);
MyChar.setValue(MyString,16) ;

Thank you in advance for your help.

2

My problem is on Arduino side, not with smartphone application.

Your problem is that you posted no code and no links to any libraries.

3

Hi,

Finally, my problem is solved !
I was extracting main lines codes from my application to post here, and had some ideas....
In fact, since Characterostics are only "unsigned char *" type when using for a string, it's obliged to cast variables used to write from or to.

Here is my simplified example.

//-------------------------------------------- Includes for BLE
#include <BLEAttribute.h>
#include <BLECentral.h>
#include <BLECharacteristic.h>
#include <BLECommon.h>
//#include <BLEDescriptor.h>
#include <BLEPeripheral.h>
#include <BLEService.h>
#include <BLETypedCharacteristic.h>
#include <BLETypedCharacteristics.h>
#include <BLEUuid.h>
#include <CurieBLE.h>

//----------------------------------------------------------- BLE declaring
BLEPeripheral blePeripheral;
BLEService InitAdmin("41300000-EB90-09D7-0001-413031360000");
BLECharacteristic Ssid("41300001-EB90-09D7-0001-413031360000", BLERead | BLEWrite,16);

//---------------------------------------------------------------------- Global Variables
int i;
char SsidLocal[32] ;

//----------------------------------------------------------------- Initialisation

void setup()
{
Serial.begin(9600);

// Set advertised local name and service UUID:
blePeripheral.setLocalName("ASE_A016");
blePeripheral.setDeviceName("ASE_A016");
blePeripheral.setAppearance(true);

// No visible service ?
//blePeripheral.setAdvertisedServiceUuid(InitAdmin.uuid());

// Add Service & Caracteristic
blePeripheral.addAttribute(InitAdmin);
blePeripheral.addAttribute(Ssid);

// Write into the SSID characteristic
sprintf(SsidLocal,"AZERTYUIOPQSDFGH");
Ssid.setValue((unsigned char *)SsidLocal,16) ; // Needs to cast because setValue accepts only unsigned char *

// begin advertising BLE service:
blePeripheral.begin();

Serial.println("A016 peripheral running...");
Serial.println("");

}

//----------------------------------------------------------------------- Main loop
void loop()
{
// listen for BLE peripherals to connect:
BLECentral central = blePeripheral.central();

// if a central is connected to peripheral:
if (central)
{
// print the central's MAC address:
Serial.print("Connected to central: ");
Serial.println(central.address());

// while the central is still connected to peripheral:
while (central.connected())
{
if (Ssid.written()) // le SSID
{
Serial.print("Admin : SSID recu ");
sprintf(SsidLocal,(char *)Ssid.value()); // Needs to cast because Value is unsigned char *
Serial.println(SsidLocal);
}
delay(250);
}

// when the central disconnects, print it out:
Serial.print("Disconnected from central: ");
Serial.println(central.address());
Serial.println();

}
}

If this may help someone !

Regards.