iOS Configure Beacons with CoreBluetooth Write major value
Example
- You need discover the services and characteristic
- You don't need read value from the characteristic before writing over it.
- will continue for, for this example, after read value. Modify func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?)
- Add a variable new_major and reset_characteristic
var reset_characteristic : CBCharacteristic!
func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
for characteristic in service.characteristics! {
print("Characteristic: \(characteristic)\n error: \(error)")
if(characteristic.uuid.uuidString == "FFF2"){
peripheral.readValue(for: characteristic)
}
if(characteristic.uuid.uuidString == "FFFF"){
reset_characteristic = characteristic
}
}
}
let new_major : UInt16 = 100
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
print("Characteristic read: \(characteristic)\n error: \(error)")
let major = UInt16.init(bigEndian: UInt16(data: characteristic.value!)!)
print("major: \(major)")
peripheral.writeValue(new_major.data, for: characteristic, type: CBCharacteristicWriteType.withResponse)
}
- iPhone by deafult will send and receive bytes in Little Endian format, but my device MINEW witch chipset NRF51822 have ARM archteture and need bytes in Big Endian format, so I have to swap it.
- BLE Device documentation will say what type of input and output each characteristic will have and if you can read it like above (CBCharacteristicWriteType.withResponse).
func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
print("Characteristic write: \(characteristic)\n error: \(error)")
if(characteristic.uuid.uuidString == "FFF2"){
print("Resetting")
peripheral.writeValue("minew123".data(using: String.Encoding.utf8)!, for: reset_characteristic, type: CBCharacteristicWriteType.withResponse)
}
if(characteristic.uuid.uuidString == "FFFF"){
print("Reboot finish")
cb_manager.cancelPeripheralConnection(peripheral)
}
}
- To update a gatt server information you have to reboot it programmatically or save data to it and turn off and turn on manually.
- FFFF is characteristic that do it in this device.
- 'minew123' is the default password for reboot o save information in this case.
- run your app and watch you console for any error, I hope none, but you will not see the new value yet.
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
print("Characteristic read: \(characteristic)\n error: \(error)")
let major = UInt16.init(bigEndian: UInt16(data: characteristic.value!)!)
print("major: \(major)")
//peripheral.writeValue(new_major.data, for: characteristic, type: CBCharacteristicWriteType.withResponse)
}
- Last step is to comment last line in method didUpdateValueFor and rerun the app, now you will the new value.
