Data transmission over Wifi

[FrancoisCosta]

Hi Paul!

As I briefly mentioned in the Python version's issues, my project involves monitoring heart rate (& HRV) during sleep with real-time analysis.
To avoid disrupting sleep (and reducing the risk of my laptop getting thrown off the bed in the middle of the night...) I aim to log data throughout the night without a serial connection between the arduino board (Feather 32u4) and laptop.

However, on the documentation I see either a USB or SD version (which would not allow real time analysis). Is there a wireless option (Wi-Fi/BT)?

The data (RR-intervals) should be transferred over Wi-Fi or BT to firstly my computer, and then, as the project progresses, directly to a raspberry Pi.

Thanks! :)

[paulvangentcom]

I'll have a look into wireless protocols and see if I can expand the module.

[FrancoisCosta]

Perfect! Thanks Paul.

[FrancoisCosta]

Hi Paul,
Any update on the wireless implementation? As I'm attempting real-time analysis using a wearable, data transfer over wifi is critical..

Thanks! :)
Francois

[paulvangentcom]

Hi Francois,

Not yet I'm afraid. I need to find the time to fit heartpy work in between my phd work so it doesn't always work out...

I hope this weekend I can have a look.

-Paul

[FrancoisCosta]

Of course, I understand. This weekend would be perfect! thanks :)

[FrancoisCosta]

Hi Paul, any luck with this?

Sorry to keep asking - this functionality is somewhat critical to advancing my project.

Thanks! :)

[paulvangentcom]

If you're in a hurry I suggest you look at Xbee, they have some wireless data transfer capabilities that are Arduino compatible. You may need to set up a buffer and send the data in batches.

The wifi capability is on my radar but has no ETA right now. Other things take precedent in my planning at the moment.

-Paul

[FrancoisCosta]

Ok! Thanks, I'll give that a go in the next couple of days and let you know how it goes.

Francois

[FrancoisCosta]

Hi Paul,

I'm currently working on a WiFi script for the Feather Huzzah ESP32 board.
However the timerInterrupt function used for the ATmega16U4/32U4/328p boards in the script provided does not work on the ESP32.

I have separate scripts working for both the WiFi transfer and a 1ms interrupt on the ESP32. However, I don't understand the SimpleLogger_Scaling_AVR_USB.ino sketch well enough to be able to implement the new interrupt while still logging the pulse sensor values, let alone send these values over Wi-Fi.

The line by line breakdown of the timer interrupt script I am using can be found here:
https://techtutorialsx.com/2017/10/07/esp32-arduino-timer-interrupts/

Would you be able to implement this interrupt within the original sketch? Once I'm able to receive the sensor values I'll keep working on the Wi-Fi data transfer.

interrupt sketch code below

volatile int interruptCounter;
int totalInterruptCounter;

hw_timer_t * timer = NULL;
portMUX_TYPE timerMux = portMUX_INITIALIZER_UNLOCKED;

void IRAM_ATTR onTimer() {
portENTER_CRITICAL_ISR(&timerMux);
interruptCounter++;
portEXIT_CRITICAL_ISR(&timerMux);

}

void setup() {

Serial.begin(115200);

timer = timerBegin(0, 80, true);
timerAttachInterrupt(timer, &onTimer, true);
timerAlarmWrite(timer, 1000000, true);
timerAlarmEnable(timer);

}

void loop() {

if (interruptCounter > 0) {

portENTER_CRITICAL(&timerMux);
interruptCounter--;
portEXIT_CRITICAL(&timerMux);

totalInterruptCounter++;

Serial.print("An interrupt as occurred. Total number: ");
Serial.println(totalInterruptCounter);

}
}

[paulvangentcom]

As the tutorial states, you need to replace

totalInterruptCounter++;

Serial.print("An interrupt as occurred. Total number: ");
Serial.println(totalInterruptCounter);

with what you want to call in the interrupt function. This is the function readSensors(dataBuf); in the original sketch.

Also see here for an alternative way of setting a hardware timer in that environment: http://www.iotsharing.com/2017/06/how-to-use-interrupt-timer-in-arduino-esp32.html

Make sure you set the timer to the correct interval so you get the sampling rate you want.

[FrancoisCosta]

cool! Will give this a go, thanks :)