I am writing a code in swift to get data from a BLE device (Omron BP7000). I am able to pair with it and get the other service and read the data. But I am unable to get the data of the blood pressure, in didUpdateValueFor characteristic:. Other delegate of CoreBluetooth have been used and are working as expected. Just when it comes to read/write data to Current time and read data from the Blood pressure characteristic I get the issue. If anyone can post some suggest of how should I proceed will be helpful.
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
switch characteristic.uuid {
case batteryLevelCBUUID:
print("Battery level: \(characteristic.value![0])")
let valueBattery = characteristic.value?[0]
batteryLabel.text = "Battery Level =" + " " + String(describing: characteristic.value! [0]) + "%"
centerView.isHidden = false
case currentTimeCBUUID:
peripheral.readValue(for: characteristic)
let currentDate = Date()
// Write the date and time to the characteristic
writeCurrentTime(to: characteristic, in: peripheral)
// print("\(characteristic.value as Any) gives Current Time String ")
if let dateTime = extractDateTime(from: characteristic) {
print("Date and Time:", dateTime)
} else {
print("Unable to extract date and time from the characteristic.")
}
case bloodPressureMeasurementCBUUID:
decodeBloodPressureMeasurementData(from: characteristic)
print("\(characteristic.value as Any) gives 2A35 ")
default:
print("")
}
}
func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
if let error = error {
// Handle write error
print("Error writing value: \(error.localizedDescription)")
} else {
// Handle successful write
print("Value written successfully")
// Check if the characteristic supports notifications
if characteristic.properties.contains(.notify) {
peripheral.setNotifyValue(true, for: characteristic)
}
}
}
func writeCurrentTime(to characteristic: CBCharacteristic, in peripheral: CBPeripheral) {
// Get the current date and time
let currentDate = Date()
let calendar = Calendar.current
var components = calendar.dateComponents([.year, .month, .day, .hour, .minute, .second, .weekday, .nanosecond], from: currentDate)
// Create the value to be written
var value = Data()
value.append(Data(bytes: &components.year!, count: 2)) // Year (2 bytes)
value.append(Data(bytes: "", count: 0))
value.append(UInt8(components.month!)) // Month (1 byte)
value.append(UInt8(components.day!)) // Day (1 byte)
value.append(UInt8(components.hour!)) // Hours (1 byte)
value.append(UInt8(components.minute!)) // Minutes (1 byte)
value.append(UInt8(components.second!)) // Seconds (1 byte)
value.append(UInt8(components.weekday!)) // Day of Week (1 byte)
value.append(contentsOf: components.nanosecond!.bytes(2)) // Fractions of a second (2 bytes)
// Write the value to the Current Time characteristic
peripheral.writeValue(value, for: characteristic, type: .withResponse)
}
func decodeBloodPressureMeasurementData(from characteristic: CBCharacteristic) {
guard let data = characteristic.value else {
print("No data available for decoding.")
return
}
let flags = data[0] // Flags byte
let unitFlags = (flags & 0b00000001) // Bit 0 indicates the unit of blood pressure values
let timestampFlags = (flags & 0b00000010) // Bit 1 indicates the presence of timestamp
// Decode systolic, diastolic, and mean arterial pressure values
let systolicPressure = (data[1] + (data[2] << 8))
let diastolicPressure = (data[3] + (data[4] << 8))
let meanArterialPressure = (data[5] + (data[6] << 8))
// Decode pulse rate value
let pulseRate = (data[7] + (data[8] << 8))
// Decode unit of blood pressure values
let unit: String = (unitFlags != 0) ? "kPa" : "mmHg"
// Process and use the decoded values as needed
print("Systolic Pressure: \(systolicPressure) \(unit)")
print("Diastolic Pressure: \(diastolicPressure) \(unit)")
print("Mean Arterial Pressure: \(meanArterialPressure) \(unit)")
print("Pulse Rate: \(pulseRate) bpm")
}
[1]: https://i.sstatic.net/fYaxj.png
I have found the answer for this issue. I was using Data() and instead of that when I used NSMutableData() it started working and connected to the BLE device (Omron BP 7000). Following is the code for the answer I have used.
// Define the CurrentTime structure
struct DateAndTime {
var year: UInt16
var month: UInt8
var day: UInt8
var hours: UInt8
var minutes: UInt8
var seconds: UInt8
}
struct CurrentTime {
var dateData : DateAndTime
var dayOfWeek: UInt8
var fractions256: UInt8
var adjustReason: UInt8
}
func writeCurrentTime(to characteristic: CBCharacteristic, in peripheral: CBPeripheral){
// Get the current date and time
let currentDate = Date()
let calendar = Calendar.current
let components = calendar.dateComponents([.year, .month, .day, .hour, .minute, .second, .weekday, .nanosecond], from: currentDate)
// Send the bytes to the BLE device
let data = NSMutableData()
let time = DateAndTime(year: UInt16(components.year!), month: (UInt8(components.month!) + 1), day: (UInt8(components.day!)), hours: (UInt8(components.hour!)), minutes: (UInt8(components.minute!)), seconds: (UInt8(components.second!)))
// Create an instance of CurrentTime with current date and time
let currentTime = CurrentTime(dateData: time, dayOfWeek: (components.btDayOfWeek), fractions256: UInt8(components.nanosecond! * 256 / Int(NSEC_PER_SEC)), adjustReason: 0) // Replace with the actual year
// Convert the CurrentTime structure to Data
let currentTimeData = withUnsafeBytes(of: currentTime) { Data($0) }
data.append(currentTimeData)
// Write the value to the Current Time characteristic
peripheral.writeValue(data as Data, for: characteristic, type: .withResponse)
}