I need to send a write command to Bluetooth low energy device. The read command works fine but i'm stuck in sending write command.

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C#

{
....
//Finding the write characteristic
//uint8_t val = 1;
//NSData* valData = [NSData dataWithBytes:(void*)&val length:sizeof(val)];
NSData* valData = @"1301040238faba000bca3c";
[peripheral writeValue:valData forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse];
.....
}

- (void) peripheral:(CBPeripheral *)peripheral didWriteValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
{
    NSLog(@"Did write characteristic value : %@ with ID %@", characteristic.value, characteristic.UUID);
    NSLog(@"With error: %@", [error localizedDescription]);
    
}

My problem is i have value in hexadecimal like "130104 0238faba 000bca3c"
i need to send this value to valData

Posted 8-Mar-15 0:58am

SViki

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2 solutions

Solution 1

You have created the data as a string, not a Hex value, so it is not valid. You should create it as a byte array, something like:

C++

// I am not familiar with Objective-C but it should be
// similar to the following:

uint8_t valData[] = { 0x13, 0x01, 0x04, 0x02, 0x38, 0xfa, 0xba, 0x00, 0x0b, 0xca, 0x3c;

Posted 8-Mar-15 2:25am

Richard MacCutchan

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

SViki · Accepted Answer · 2015-03-25T00:05:00

I have solved my problem. This is the sample solution.

NSMutableData *concatenate = [NSMutableData data];
uint16_t first=0x1cbd;
uint8_t second = 0x01;
uint8_t third = 0xfa;
uint8_t fourth=0xea
                
NSData* one = [NSData dataWithBytes:(void*)&first length:sizeof(first)];
NSData* two = [NSData dataWithBytes:(void*)&second length:sizeof(second)];
NSData* three = [NSData dataWithBytes:(void*)&third length:sizeof(third)];
NSData* four = [NSData dataWithBytes:(void*)&fourth length:sizeof(fourth)];
                
[concatenate appendData:one];
[concatenate appendData:two];
[concatenate appendData:three];
[concatenate appendData:four];
              
[peripheral writeValue:concatenate forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse];

I need to send a write command to Bluetooth low energy device. The read command works fine but i'm stuck in sending write command.

2 solutions

Solution 1

Solution 2

Add your solution here

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I need to send a write command to Bluetooth low energy device. The read command works fine but i'm stuck in sending write command.

2 solutions

Solution 1

Solution 2

Add your solution here

Preview 0

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