# Error when trying to send data to Thunkable app through Bluetooth
**URL:** https://community.thunkable.com/t/error-when-trying-to-send-data-to-thunkable-app-through-bluetooth/3113308
**Category:** BLE / BlueTooth
**Created:** [July 25, 2024, 3:19pm UTC](https://community.thunkable.com/t/error-when-trying-to-send-data-to-thunkable-app-through-bluetooth/3113308 "2024-07-25T15:19:07Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@chrismdisalvoohxko](https://community.thunkable.com/u/chrismdisalvoohxko)
#### Post date: [July 25, 2024, 3:19pm UTC](https://community.thunkable.com/t/error-when-trying-to-send-data-to-thunkable-app-through-bluetooth/3113308/1 "2024-07-25T15:19:07Z")
Hello,
I am trying to send multiple data values to my Thunkable app through Bluetooth. I am using an Arduino MKR WIFI 1010 to send data. I have successfully connected to my app via Bluetooth but whenever I try to send data, I get an error. I will attach below my Thunkable blocks, Arduino code, and picture of my error message. Any help and suggestions are greatly appreciated.
```auto
#include
BLEService batteryService("180F"); // Custom service UUID
BLECharacteristic batteryPercentageChar("2A19", BLERead | BLENotify, 20);
BLECharacteristic batteryVoltageChar("2A1C", BLERead | BLENotify, 20);
void setup() {
Serial.begin(9600);
while (!Serial);
if (!BLE.begin()) {
Serial.println("Starting BLE failed!");
while (1);
}
// Set advertised local name and service UUID
BLE.setLocalName("BatteryMonitor");
BLE.setAdvertisedService(batteryService);
// Add characteristics to the service
batteryService.addCharacteristic(batteryPercentageChar);
batteryService.addCharacteristic(batteryVoltageChar);
// Add the service
BLE.addService(batteryService);
// Start advertising
BLE.advertise();
Serial.println("Bluetooth device active, waiting for connections...");
}
void loop() {
BLEDevice central = BLE.central();
if (central) {
Serial.print("Connected to central: ");
Serial.println(central.address());
while (central.connected()) {
// Simulate battery percentage and voltage
int batteryPercentage = 75; // Example percentage
float batteryVoltage = 3.7; // Example voltage
// Convert to strings
String percentageStr = String(batteryPercentage);
String voltageStr = String(batteryVoltage, 2); // Two decimal places
// Write data to characteristics
batteryPercentageChar.setValue(percentageStr.c_str());
batteryVoltageChar.setValue(voltageStr.c_str());
delay(1000);
}
Serial.print("Disconnected from central: ");
Serial.println(central.address());
}
}
```
---
### Author:  [@ioannis](https://community.thunkable.com/u/ioannis)
#### Post date: [July 25, 2024, 8:01pm UTC](https://community.thunkable.com/t/error-when-trying-to-send-data-to-thunkable-app-through-bluetooth/3113308/2 "2024-07-25T20:01:47Z")
Hi @chrismdisalvoohxko , welcome to Thunkable! 🎉
Is your hardware using the NOTIFY method?
Another creator had the same issue and was able to resolve it using this method: [iOS Bluetooth App doesn’t receives any data - Questions about Thunkable / BLE / BlueTooth - Community](https://community.thunkable.com/t/ios-bluetooth-app-doesnt-receives-any-data/2419863)
---
### Author:  [@chrismdisalvoohxko](https://community.thunkable.com/u/chrismdisalvoohxko)
#### Post date: [July 26, 2024, 5:57pm UTC](https://community.thunkable.com/t/error-when-trying-to-send-data-to-thunkable-app-through-bluetooth/3113308/3 "2024-07-26T17:57:36Z")
Hi,
I figured it out! In order to send the data, I needed to use a 32-bit characteristic UUID instead of a 4-bit characteristic UUID. I was then able to read data via BLE on an Android tablet. I still have not tested this on IOS but will be soon. Here is an updated code for anyone in the future.
```auto
#include
BLEService batteryService("180F"); // Custom service UUID
// Create characteristics using 32-bit UUIDs
BLECharacteristic batteryPercentageChar("00002A19-0000-1000-8000-00805F9B34FB", BLERead | BLENotify, 20);
BLECharacteristic batteryVoltageChar("00002A1C-0000-1000-8000-00805F9B34FB", BLERead | BLENotify, 20);
void setup() {
Serial.begin(9600);
while (!Serial);
if (!BLE.begin()) {
Serial.println("Starting BLE failed!");
while (1);
}
// Set advertised local name and service UUID
BLE.setLocalName("BatteryMonitor");
BLE.setAdvertisedService(batteryService);
// Add characteristics to the service
batteryService.addCharacteristic(batteryPercentageChar);
batteryService.addCharacteristic(batteryVoltageChar);
// Add the service
BLE.addService(batteryService);
// Start advertising
BLE.advertise();
Serial.println("Bluetooth device active, waiting for connections...");
}
void loop() {
BLEDevice central = BLE.central();
if (central) {
Serial.print("Connected to central: ");
Serial.println(central.address());
while (central.connected()) {
// Simulate battery percentage and voltage
int batteryPercentage = 75; // Example percentage
float batteryVoltage = 3.7; // Example voltage
// Convert to strings
String percentageStr = String(batteryPercentage);
String voltageStr = String(batteryVoltage, 2); // Two decimal places
// Write data to characteristics
batteryPercentageChar.writeValue(percentageStr.c_str());
batteryVoltageChar.writeValue(voltageStr.c_str());
delay(1000);
}
Serial.print("Disconnected from central: ");
Serial.println(central.address());
}
}
```
---
### Author:  [@ioannis](https://community.thunkable.com/u/ioannis)
#### Post date: [July 26, 2024, 6:03pm UTC](https://community.thunkable.com/t/error-when-trying-to-send-data-to-thunkable-app-through-bluetooth/3113308/4 "2024-07-26T18:03:28Z")
Hi @chrismdisalvoohxko
Thank you for sharing an update and the code
Glad that is working now.