read of Characteristic causes disconnect
read of Characteristic causes disconnect
- Subject: read of Characteristic causes disconnect
- From: RAM KUMAR <email@hidden>
- Date: Fri, 11 Apr 2014 00:38:08 -0500
- Importance: Normal
I am implementing a central using on ios7 on an iPhone5s.
I am able to scan for devices and can connect to the desired peripheral device. As part of the overall connection procedure, I also undertake the discovery procedure of service and characteristics.
I have properties(obj-C) for the CBService - aService and CBCharacteristic aChar . As part of the didDiscoverServices , I store the service and as part of didDiscoverCharacteristicsForService and store the cache the characteristic which is has a property of 0x0A(Read/Write)
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error
{
CBUUID *svcUUID = [ CBUUID UUIDWithString:@"<SOME UUID>"];
for (CBService *service in peripheral.services)
{
NSLog(@"Service discovered - %@", service);
if([service.UUID.data isEqualToData:svcUUID.data] )
{
_aService = service;
NSLog((@"Service found"));
}
}
if(_aService)
{
dispatch_async(dispatch_get_main_queue(), ^{
[_targetDevice discoverCharacteristics:nil forService:t_aService];
});
}
}
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error
{
CBUUID *charUUID = [ CBUUID UUIDWithString:@"<some UUID>"];
for( CBCharacteristic *cs in service.characteristics)
{
NSLog(@"Characteristics discovered - %@", cs);
if([cs.UUID.data isEqualToData:charUUID.data] )
{
_aChar = cs;
NSLog(@"Characteristic %@ Found",cs);
// This works btw
[peripheral readValueForCharacteristic:_aChar];
break;
}
}
}
Now I have a button that i use to read the char . In the button handler, I use the following call to read the characteristic for the service .
-(IBAction) buttonDown:(id)sender
{
// immediate disconnection after this !
[_aService readValueForCharacteristic:_aChar];
}
I immediately see a disconnect. Any clues as to why this might me occurring?
On the other hand, I observe that if I invoke this same request in the didDiscoverCharacteristicsForService then the calls succeeds and the data is available.
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