Arduino .read() function interfering with BLE connection - c++

Question

Firstly, I want to apologize as I am new to BLE connectivity and much of Arduino programming. I am busy with a project which in involved making a smart coffee scale which can output data to a smartphone via a BLE connection. I am working with an Arduino nano 33 IoT, and an hx711 load cell amplifier.
I need to create a program where I can send and receive data to and from the Arduino to the smartphone app. I have used standard ArduinoBLE peripheral libraries such as the "BatteryMonitor" sketch and the "ButtonLED" sketch. By combining both of these example sketches together I have managed to established a connection where I can send and receive data.
The problem arises when I try to use functions within the HX711 library such as scale.read(); to retrieve values being output from the hx711 amplifier. When I use a serial read function such as scale.read() the bluetooth connection fails before establishing itself properly. I imagine this is due to the scale.read() function interfering with the serial data being transmitted and received by the Arduino, but I have no clue how to get around this problem.
I basically want to change the battery monitor output to be the output of the value read from the hx711 load cell amplifier but I am struggling to get this to work.
#include "HX711.h"
#include <ArduinoBLE.h>
HX711 scale;
BLEService ledService("19B10000-E8F2-537E-4F6C-D104768A1214"); // BLE LED Service
// BLE LED Switch Characteristic - custom 128-bit UUID, read and writable by central
BLEByteCharacteristic switchCharacteristic("19B10001-E8F2-537E-4F6C-D104768A1214", BLERead | BLEWrite);
BLEUnsignedCharCharacteristic batteryLevelChar("2A19", // standard 16-bit characteristic UUID
BLERead | BLENotify); // remote clients will be able to get notifications if this characteristic changes
int oldBatteryLevel = 0; // last battery level reading from analog input
long previousMillis = 0; // last time the battery level was checked, in ms
const int ledPin = LED_BUILTIN; // pin to use for the LED
double val;
void setup() {
Serial.begin(9600);
scale.begin(A1, A0); //Initialized scale on these pins
while (!Serial);
scale.set_scale(432.f); // this value is obtained by calibrating the scale with known weights; see the README for details
scale.tare(); // reset the scale to 0
// set LED pin to output mode
pinMode(ledPin, OUTPUT);
// begin initialization
if (!BLE.begin()) {
Serial.println("starting BLE failed!");
while (1);
}
// set advertised local name and service UUID:
BLE.setLocalName("COFFEE");
BLE.setAdvertisedService(ledService);
// add the characteristic to the service
ledService.addCharacteristic(switchCharacteristic);
ledService.addCharacteristic(batteryLevelChar); // add the battery level characteristic
// add service
BLE.addService(ledService);
// set the initial value for the characeristic:
switchCharacteristic.writeValue(0);
// start advertising
BLE.advertise();
Serial.println("BLE LED Peripheral");
}
void loop()
{
// listen for BLE peripherals to connect:
BLEDevice central = BLE.central();
// if a central is connected to peripheral:
if (central) {
Serial.print("Connected to central: ");
// print the central's MAC address:
Serial.println(central.address());
// while the central is still connected to peripheral:
while (central.connected())
{
// Battery Monitor
// scale.read();
long currentMillis = millis();
// if 200ms have passed, check the battery level:
if (currentMillis - previousMillis >= 200) {
previousMillis = currentMillis;
// scale.read(); // This function alone will prevent the BLE connection from establishing properly.
updateBatteryLevel();
// outputScale();
}
// if the remote device wrote to the characteristic,
// use the value to control the LED:
if (switchCharacteristic.written()) {
if (switchCharacteristic.value()) { // any value other than 0
Serial.println("LED on");
digitalWrite(ledPin, HIGH); // will turn the LED on
} else { // a 0 value
Serial.println(F("LED off"));
digitalWrite(ledPin, LOW); // will turn the LED off
}
}
}
// when the central disconnects, print it out:
Serial.print(F("Disconnected from central: "));
Serial.println(central.address());
}
}
void updateBatteryLevel()
{
/* Read the current voltage level on the A0 analog input pin.
This is used here to simulate the charge level of a battery.
*/
int battery = analogRead(A0);
int batteryLevel = map(battery, 0, 1023, 0, 100);
if (batteryLevel != oldBatteryLevel) { // if the battery level has changed
// Serial.print("Battery Level % is now: "); // print it
Serial.println(batteryLevel);
batteryLevelChar.writeValue(batteryLevel); // and update the battery level characteristic
oldBatteryLevel = batteryLevel; // save the level for next comparison
}
}
void outputScale(){
int t, i, n, T;
double val, sum, sumsq, mean;
float stddev;
n = 20;
t = millis();
i = sum = sumsq = 0;
while (i<n) {
val = ((scale.read() - scale.get_offset()) / scale.get_scale());
sum += val;
sumsq += val * val;
i++;
}
t = millis() - t;
mean = sum / n;
stddev = sqrt(sumsq / n - mean * mean);
// Serial.print("Mean, Std Dev of "); Serial.print(i); Serial.print(" readings:\t");
Serial.print(sum / n, 3); Serial.print("\n"); // Serial.print(stddev, 3);
// Note: 2 sigma is 95% confidence, 3 sigma is 99.7%
//Serial.print("\nTime taken:\t"); Serial.print(float(t)/1000, 3); Serial.println("Secs\n");
/*
scale.power_down(); // put the ADC in sleep mode
delay(5000);
scale.power_up();
*/
}

Answer 1

You are initialising as scale.begin(A1, A0) while trying to read from the same A0 pin.