MAX30100 Pulseoxymeter showing random characters

Using Arduino Programming Questions
1

Hi, I'm trying to display the heart rate on this sensor, but the only thing that's showing is that the oxmeter is running fine, but after that, it doesn't show me the heart beats, but it's showing me something like " ???[??[?????[??????????????M??????????". I'm new to this and I don't know what to do.

2

Please post your code

The easier you make it to read and copy your code the more likely it is that you will get help

Please follow the advice given in the link below when posting code , use code tags and post the code here

If you get errors when compiling please copy them from the IDE using the "Copy error messages" button and paste the clipboard here in code tags

3

Does the serial speed of the serial monitor match the serial speed of your secret sketch?

4 
#include <Wire.h>
#include "MAX30100_PulseOximeter.h"
 
#define REPORTING_PERIOD_MS     1000
 
PulseOximeter pox;
uint32_t tsLastReport = 0;
 
void onBeatDetected()
{
    Serial.println("Beat!");
}
 
void setup()
{
    Serial.begin(115200);
    Serial.print("Initializing pulse oximeter..");
 
    // Initialize the PulseOximeter instance
    // Failures are generally due to an improper I2C wiring, missing power supply
    // or wrong target chip
    if (!pox.begin()) {
        Serial.println("FAILED");
        for(;;);
    } else {
        Serial.println("SUCCESS");
    }
     //pox.setIRLedCurrent(MAX30100_LED_CURR_7_6MA);
 
    // Register a callback for the beat detection
    pox.setOnBeatDetectedCallback(onBeatDetected);
}
 
void loop()
{
    // Make sure to call update as fast as possible
    pox.update();
    if (millis() - tsLastReport > REPORTING_PERIOD_MS) {
        Serial.print("Heart rate:");
        Serial.print(pox.getHeartRate());
        Serial.print("bpm");
 
        tsLastReport = millis();
    }
}
5

My secret sketch isn't even secret, is taken from this forum Interfacing MAX30100 Pulse Oximeter Sensor with Arduino . Also I own the purple oximeter.

6

It was until you posted it and you did that wrong too

The easier you make it to read and copy your code the more likely it is that you will get help

Please follow the advice given in the link below when posting code , use code tags and post the code here

If you get errors when compiling please copy them from the IDE using the "Copy error messages" button and paste the clipboard here in code tags

7

I've edited my code. The problem is not in compiling, it is in the serial monitor. The only thing that's showing right, it's the Serial print with Initializing pulse oximeter .. SUCCESS, shortly after, the only thing that's showing are just a bunch of random question marks and some random letters, instead of Beat! or Heart rate: ... bpm.

8

How is the oximeter wired to the Arduino?

9

The setup is :

VIN -   5V 
GND -  GND
SCL - A5
SDA - A4
10

Maybe try the debugging example from the library.

11

I found the sollution, the only thing that I had to do, I had to lower the Serial.begin from 112500 to 9500.

12

...both of which are pretty unusual values.

13

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