Monitor Heart Rate on SnapEmu with a Wireless Tracker

We can use the free cloud platform SnapEmu to monitor our daily health status. The platform's app provides data visualization and can track data for up to a month, offering an effective solution for everyday health monitoring. In addition, SnapEmu supports user local, server, or gateway deployment. For more detailed features, please refer to this document.

1.Hardware configuration

Hardware pin connection

This is the detailed pin diagram of the wireless tracker.

Note:When connecting input and output pins, try to connect pins that do not have built-in other functions as much as possible.

2.Software Configuration

2.1 Configure HT-7603 Gateway on SnapEmu

2.2Configure Tracker Node on SnapEmu

2.3Sensor reading

#include <Wire.h>
#include "MAX30102_PulseOximeter.h"
#define REPORTING_PERIOD_MS 1000
PulseOximeter pox;
uint32_t tsLastReport = 0;
void onBeatDetected() {
Serial.println("Beat detected!");
}
void setup() {
Serial.begin(115200);
Wire.begin(45,46);
Serial.print("Initializing MAX30102..");
delay(3000);
if (!pox.begin()) {
Serial.println("FAILED");
for(;;);
} else {
Serial.println("SUCCESS");
}
pox.setIRLedCurrent(MAX30102_LED_CURR_7_6MA);
pox.setOnBeatDetectedCallback(onBeatDetected);
}
void loop() {
pox.update();
if (millis() - tsLastReport > REPORTING_PERIOD_MS) {
float heartRate = pox.getHeartRate();
float spo2 = pox.getSpO2();
if (heartRate > 0) {
Serial.print("Heart rate: ");
Serial.print(heartRate);
Serial.print(" bpm / ");
} else {
Serial.print("Heart rate: N/A / ");
}
if (spo2 > 0) {
Serial.print("SpO2: ");
Serial.print(spo2);
Serial.print(" %");
} else {
Serial.print("SpO2: N/A");
}
Serial.println();
tsLastReport = millis();
}
}

After serial port reading

2.4 Upload data to Heltec Snapemu platform

Upload data to SnapEmu via gateway using LoRaWAN protocol.

Note: sensor data needs to be encapsulated into a specified data format before it can be uploaded to the cloud platform.

#include <Wire.h>
#include "MAX30102_PulseOximeter.h"
#include "LoRaWan_APP.h"
#define REPORTING_PERIOD_MS 1000
/* OTAA para*/
uint8_t devEui[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xA8 };
uint8_t appEui[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
uint8_t appKey[] = { 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88 };
/* ABP para*/
uint8_t nwkSKey[] = { 0x15, 0xb1, 0xd0, 0xef, 0xa4, 0x63, 0xdf, 0xbe, 0x3d, 0x11, 0x18, 0x1e, 0x1e, 0xc7, 0xda, 0x85 };
uint8_t appSKey[] = { 0xd7, 0x2c, 0x78, 0x75, 0x8c, 0xdc, 0xca, 0xbf, 0x55, 0xee, 0x4a, 0x77, 0x8d, 0x16, 0xef, 0x67 };
uint32_t devAddr =  ( uint32_t )0x007e6ae1;
/*LoraWan channelsmask, default channels 0-7*/
uint16_t userChannelsMask[6]={ 0x00FF,0x0000,0x0000,0x0000,0x0000,0x0000 };
/*LoraWan region, select in arduino IDE tools*/
LoRaMacRegion_t loraWanRegion = ACTIVE_REGION;
/*LoraWan Class, Class A and Class C are supported*/
DeviceClass_t  loraWanClass = CLASS_A;
/*the application data transmission duty cycle.  value in [ms].*/
uint32_t appTxDutyCycle = 15000;
/*OTAA or ABP*/
bool overTheAirActivation = true;
/*ADR enable*/
bool loraWanAdr = true;
/* Indicates if the node is sending confirmed or unconfirmed messages */
bool isTxConfirmed = true;
/* Application port */
uint8_t appPort = 2;
uint8_t confirmedNbTrials = 4;
/* Pulse Oximeter object */
PulseOximeter pox;
uint32_t tsLastReport = 0;
/* Prepare LoRa payload with heart rate and SpO2 data */
static void prepareTxFrame(uint8_t port) {
pox.update();
float heartRate = pox.getHeartRate();
float spo2 = pox.getSpO2();
unsigned char *puc;
appDataSize = 0;
appData[appDataSize++] = 0x04;
appData[appDataSize++] = 0x00;
appData[appDataSize++] = 0x0A;
appData[appDataSize++] = 0x02;
puc = (unsigned char *)(&heartRate);
appData[appDataSize++] = puc[0];
appData[appDataSize++] = puc[1];
appData[appDataSize++] = puc[2];
appData[appDataSize++] = puc[3];
appData[appDataSize++] = 0x12;  // another identifier for SpO2
puc = (unsigned char *)(&spo2);
appData[appDataSize++] = puc[0];
appData[appDataSize++] = puc[1];
appData[appDataSize++] = puc[2];
appData[appDataSize++] = puc[3];
Serial.print("Sending data: ");
for (int i = 0; i < appDataSize; i++) {
Serial.print(appData[i], HEX);
Serial.print(" ");
}
Serial.println();
// Ensure that the total size does not exceed the maximum limit
if (appDataSize > LORAWAN_APP_DATA_MAX_SIZE) {
appDataSize = LORAWAN_APP_DATA_MAX_SIZE;
}
}
void setup() {
Serial.begin(115200);
Wire.begin(45, 46);
// Initialize LoRaWAN
Mcu.begin(HELTEC_BOARD, SLOW_CLK_TPYE);
// MAX30102 Setup
Serial.print("Initializing MAX30102..");
delay(3000);
if (!pox.begin()) {
Serial.println("FAILED");
for(;;);
} else {
Serial.println("SUCCESS");
}
pox.setIRLedCurrent(MAX30102_LED_CURR_27_1MA);
pox.setOnBeatDetectedCallback(onBeatDetected);
// LoRaWAN initialization
LoRaWAN.init(loraWanClass, loraWanRegion);
LoRaWAN.setDefaultDR(3);  // Set datarate for LoRaWAN (can be adjusted)
}
void onBeatDetected() {
Serial.println("Beat detected!");
// Add additional debugging information
Serial.println("Heart rate sensor has detected a beat!");
}
void loop() {
pox.update(); // Update sensor data
if (millis() - tsLastReport > REPORTING_PERIOD_MS) {
float heartRate = pox.getHeartRate();
float spo2 = pox.getSpO2();
if (heartRate > 0) {
Serial.print("Heart rate: ");
Serial.print(heartRate);
Serial.print(" bpm / ");
} else {
Serial.print("Heart rate: N/A / ");
}
if (spo2 > 0) {
Serial.print("SpO2: ");
Serial.print(spo2);
Serial.print(" %");
} else {
Serial.print("SpO2: N/A");
}
Serial.println();
tsLastReport = millis();
}
// LoRaWAN State Machine
switch (deviceState) {
case DEVICE_STATE_INIT:
{
// Handle joining of LoRaWAN network
LoRaWAN.join();
break;
}
case DEVICE_STATE_JOIN:
{
LoRaWAN.join();
break;
}
case DEVICE_STATE_SEND:
{
// Prepare and send data over LoRaWAN
prepareTxFrame(appPort);
LoRaWAN.send();
deviceState = DEVICE_STATE_CYCLE;
break;
}
case DEVICE_STATE_CYCLE:
{
// Schedule next packet transmission
txDutyCycleTime = appTxDutyCycle + randr(-APP_TX_DUTYCYCLE_RND, APP_TX_DUTYCYCLE_RND);
LoRaWAN.cycle(txDutyCycleTime);
deviceState = DEVICE_STATE_SLEEP;
break;
}
case DEVICE_STATE_SLEEP:
{
LoRaWAN.sleep(loraWanClass);
break;
}
default:
{
deviceState = DEVICE_STATE_INIT;
break;
}
}
}

Due to the MAX30102 sensor not being within the automatic decoding range of the platform, the platform is unable to automatically decode the ultrasonic sensor data. Therefore, we need to write decoding functions to display real-time data on the platform application interface. This document provides detailed operations.

After successfully accessing the network, there will be an updatalink.

3.Application interface display

After successful decoding, the SnapEmu platformapplication interface will display as shown in the figure.

3.1Web Version

3.2APP Version