https://www.youtube.com/watch?v=eeJpgbeWJrI
replace _GT_ with greater than symbol
replace _LT_ with less than symbol
youtube dont like angle brackets

ble no scan get nrf connect in google store to find your ble id

#filename:uart_test.py
#uses hm19 ble module - amazon item #8541588324
#pico pin4       - hm-19 rxd
#pico pin5       - hm-19 txd
#pico pin40      - hm-19 vcc
from machine import UART,ADC
import time
t=ADC(4)
uart=UART(1,9600)
while 1:
    time.sleep_ms(500)
    uart.write(str(t.read_u16()))
    
////////////////filename: main.dart
//change in build.gradle - minSdkVersion 21
//give this app location permission and turn on bluetooth on your phone/tablet
//add plugins - flutter_reactive_ble and get
import 'package:flutter/material.dart';
import 'package:get/get.dart';
import './blecontroller.dart';

void main() {
  runApp(MyApp());}

class MyApp extends StatelessWidget {
@override Widget build(BuildContext context) {
return GetMaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,),
home: MyHomePage());}}

class MyHomePage extends StatelessWidget {
TextStyle myStyle = TextStyle(fontSize: 30);  
final BleController c = Get.put(BleController());
MyHomePage();
@override Widget build(BuildContext context){   
return Scaffold(
appBar: AppBar(title: Text('ble test')),
body: Column(children: _LT_Widget_GT_[

  SizedBox(height:50),
            
  Obx(() =_GT_ Text('${c.status}',
    style:myStyle)),
    
  SizedBox(height:50),
            
  Obx(() =_GT_ Text('pico adc(4) value: ${c.temperature}',
    style:myStyle)),
    
  SizedBox(height:50),
    
  Obx(() =_GT_ Container(
    child: c.status != 'connected!'
      ? ElevatedButton(onPressed: c.connect,
          child: Text('connect',
            style:myStyle))
      : null))]));}}
      
//////////////////// filename: blecontroller.dart
// ble no scan get nrf connect in google play store to get ble id
import 'package:flutter/material.dart';
import 'package:flutter_reactive_ble/flutter_reactive_ble.dart';
import 'dart:async';
import 'package:get/get.dart';

class BleController {
final frb = FlutterReactiveBle();
late StreamSubscription_LT_ConnectionStateUpdate_GT_ connection;
late QualifiedCharacteristic rx;
RxString status = 'not connected'.obs;
RxString temperature = ' '.obs;

void connect() async {
status.value = 'connecting...';
connection = frb.connectToDevice(id: 'A4:DA:32:55:06:1E').listen((state){
if (state.connectionState == DeviceConnectionState.connected){         
  status.value = 'connected!';
  
  // get rx
  rx = QualifiedCharacteristic(
    serviceId: Uuid.parse("0000ffe0-0000-1000-8000-00805f9b34fb"),            
    characteristicId: Uuid.parse("0000ffe1-0000-1000-8000-00805f9b34fb"), 
    deviceId:'A4:DA:32:55:06:1E' );
              
  // subscribe to rx
  frb.subscribeToCharacteristic(rx).listen((data){
    temperature.value = String.fromCharCodes(data);
});}});}}