Not Displaying Any Value on Blynk App with nodemcu ESP32 + dfrobot heart rate sensor

Need Help With My Project
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1

Hi, everyone. I have been working on a project that connect nodemcu esp32 with dfrobot heart rate sensor link and I just can’t get any value being display on the app. There’s only 3 wires that connect between the nodemcu esp 32 and dfrobot heart rate sensor. I also been following the tutorial from this youtube videotutorial esp8266 but it wont work on my app, just no value display. ps: I have tested it on esp8266 too but it won’t work as the video shown). I have been struggling, any help with be appreciated.

Here as follows
nodemcu esp 32 ------------------ Dfrobot heart rate sensor
GND ----------------- GND
3.3v ----------------- VCC
GPIO 32 ----------------- Signal

• Smartphone OS - Redmi K20 Pro[MIUI 11.0.8 ] / Xiao Mi A2 Lite (Tested on both devices)
• Blynk Library version : v.0.6.1
• Code:


#define heartratePin 32
#include "DFRobot_Heartrate.h"
#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>


DFRobot_Heartrate heartrate(DIGITAL_MODE); ///< ANALOG_MODE or DIGITAL_MODE


BlynkTimer timer;
char auth[] = "zSgIpS-vRCeOEohVzuHWlaVpBNl5eaxG";                              
char ssid[] = "Gummya";    
char pass[] = "testtest1";  

void setup() {
  Serial.begin(115200);
  Blynk.begin(auth, ssid, pass);
  timer.setInterval(2000L, sendUptime);
}

void sendUptime() {
  uint8_t rateValue;
  heartrate.getValue(heartratePin); ///< A1 foot sampled values
  rateValue = heartrate.getRate(); ///< Get heart rate value 
  if(rateValue)  {
    Blynk.virtualWrite(V98,rateValue);
    Serial.println(rateValue);
  }

  //delay(20);
}

void loop() {
  
  Blynk.run();
  timer.run();
 
}

Anyone are welcome to comment if you happen to have any idea to tackle this issue. Thanks in advance.

Regards
yys100

2

I think the issue is that the code that looks for pulses is meant to run in the void loop - which probably won’t work well with Blynk.
You’re calling the timed function once every 2 seconds. If the sensor detects a pulse at exactly the moment when the timed function is called then you’ll get a result, but the odds on that happening are pretty slim.

I think you’d probably be better-off using an interrupt, but I doubt whether you’ll get the sort of results you’re hoping for when using Superchart.

Pete.

3

Hi, thanks for getting back to me. As for the suggestion using interrupt, could you please provide me an example so that I could work on it as my programming skill is not very good. Besides, are they any alternatives that display the value I want on the app for my case? I would like to try it out. If would be good if you could point out what I should add/change in my code and I’ll be grateful to you. And I am just using the widget gauge to display value (using digital mode), that’s what I want.

Thanks

Regards
yys100

4

I’d suggest that you do a bit of searching for interrupt examples.

Blynk is an IoT app, and isn’t really aimed at the sort of things you’re trying to do. Give it a go by all means, but I wouldn’t put too much time and effort into it.

Pete.