Fix "Low memory available, stability problems may occur."

Hi, I am testing with example code of Sparkfun MAX3010x to see SPO2
So, I get this error and want to know how to solve it.

Code:

#include <Wire.h>
#include "MAX30105.h"
#include "spo2_algorithm.h"

MAX30105 particleSensor;

#define MAX_BRIGHTNESS 255

#if defined(AVR_ATmega328P) || defined(AVR_ATmega168)
//Arduino Uno doesn't have enough SRAM to store 100 samples of IR led data and red led data in 32-bit format
//To solve this problem, 16-bit MSB of the sampled data will be truncated. Samples become 16-bit data.
uint16_t irBuffer[100]; //infrared LED sensor data
uint16_t redBuffer[100]; //red LED sensor data
#else
uint32_t irBuffer[100]; //infrared LED sensor data
uint32_t redBuffer[100]; //red LED sensor data
#endif

int32_t bufferLength; //data length
int32_t spo2; //SPO2 value
int8_t validSPO2; //indicator to show if the SPO2 calculation is valid
int32_t heartRate; //heart rate value
int8_t validHeartRate; //indicator to show if the heart rate calculation is valid

byte pulseLED = 11; //Must be on PWM pin
byte readLED = 13; //Blinks with each data read

void setup()
{
Serial.begin(115200); // initialize serial communication at 115200 bits per second:

pinMode(pulseLED, OUTPUT);
pinMode(readLED, OUTPUT);

// Initialize sensor
if (!particleSensor.begin(Wire, I2C_SPEED_FAST)) //Use default I2C port, 400kHz speed
{
Serial.println(F("MAX30105 was not found. Please check wiring/power."));
while (1);
}

Serial.println(F("Attach sensor to finger with rubber band. Press any key to start conversion"));
while (Serial.available() == 0) ; //wait until user presses a key
Serial.read();

byte ledBrightness = 60; //Options: 0=Off to 255=50mA
byte sampleAverage = 4; //Options: 1, 2, 4, 8, 16, 32
byte ledMode = 2; //Options: 1 = Red only, 2 = Red + IR, 3 = Red + IR + Green
byte sampleRate = 100; //Options: 50, 100, 200, 400, 800, 1000, 1600, 3200
int pulseWidth = 411; //Options: 69, 118, 215, 411
int adcRange = 4096; //Options: 2048, 4096, 8192, 16384

particleSensor.setup(ledBrightness, sampleAverage, ledMode, sampleRate, pulseWidth, adcRange); //Configure sensor with these settings
}

void loop()
{
bufferLength = 100; //buffer length of 100 stores 4 seconds of samples running at 25sps

//read the first 100 samples, and determine the signal range
for (byte i = 0 ; i < bufferLength ; i++)
{
while (particleSensor.available() == false) //do we have new data?
particleSensor.check(); //Check the sensor for new data

redBuffer[i] = particleSensor.getRed();
irBuffer[i] = particleSensor.getIR();
particleSensor.nextSample(); //We're finished with this sample so move to next sample

Serial.print(F("red="));
Serial.print(redBuffer[i], DEC);
Serial.print(F(", ir="));
Serial.println(irBuffer[i], DEC);

}

//calculate heart rate and SpO2 after first 100 samples (first 4 seconds of samples)
maxim_heart_rate_and_oxygen_saturation(irBuffer, bufferLength, redBuffer, &spo2, &validSPO2, &heartRate, &validHeartRate);

//Continuously taking samples from MAX30102. Heart rate and SpO2 are calculated every 1 second
while (1)
{
//dumping the first 25 sets of samples in the memory and shift the last 75 sets of samples to the top
for (byte i = 25; i < 100; i++)
{
redBuffer[i - 25] = redBuffer[i];
irBuffer[i - 25] = irBuffer[i];
}

//take 25 sets of samples before calculating the heart rate.
for (byte i = 75; i < 100; i++)
{
  while (particleSensor.available() == false) //do we have new data?
    particleSensor.check(); //Check the sensor for new data

  digitalWrite(readLED, !digitalRead(readLED)); //Blink onboard LED with every data read

  redBuffer[i] = particleSensor.getRed();
  irBuffer[i] = particleSensor.getIR();
  particleSensor.nextSample(); //We're finished with this sample so move to next sample

  //send samples and calculation result to terminal program through UART
  Serial.print(F("red="));
  Serial.print(redBuffer[i], DEC);
  Serial.print(F(", ir="));
  Serial.print(irBuffer[i], DEC);

  Serial.print(F(", HR="));
  Serial.print(heartRate, DEC);

  Serial.print(F(", HRvalid="));
  Serial.print(validHeartRate, DEC);

  Serial.print(F(", SPO2="));
  Serial.print(spo2, DEC);

  Serial.print(F(", SPO2Valid="));
  Serial.println(validSPO2, DEC);
}

//After gathering 25 new samples recalculate HR and SP02
maxim_heart_rate_and_oxygen_saturation(irBuffer, bufferLength, redBuffer, &spo2, &validSPO2, &heartRate, &validHeartRate);

}
}

Please format and post your code according to this:

Read this before posting a programming question ...

After that we can help.

Which processor are you using?
Something with 32 K PROGMEM / 2K RAM, but not a 328P?

(The code has too many magic numbers)

It baffles me how people can manage to post large, unformatted programs with selected chunks in the middle being properly posted with Code Tags.

If you have to have 100 samples then you could use an Arduino Mega.

The stability statement is a warning but it may run fine. If it does the only downside is you don't have much memory for modifications or enhancements to the code.

1 Like

I suspect that something in forum code tries to recognize code and automatically insert code tags (like it recognizes links).


I thought it was solved like above. But after researching, I think I have to use Arduino Mega to have more memory.

Or seriously trim and optimise your use of SRAM.

(Why do people call it SRAM ? It’s just RAM.)

Static RAM doesn't have to be constantly refreshed as opposed to dynamic RAM.

'Cos it's not DRAM or FRAM

So what’s the S for ?

In the old days, it was ‘static’ RAM, or alternately dynamic RAM…..

I just noticed the SRAM moniker creeping in over the past few years :hugs: