KW40 Heart rate sensor

syed_idris — Mon, 04 Apr 2016 06:46:18 GMT

Hi,

We debugged the "heart rate sensor" example code in USB-KW40 using IAR and able to see the data on "Kinetis BLE toolbox" application,

it is giving the data in between 40 to 50 bpm. But in the code it is written as

#define mHeartRateLowerLimit_c (40) /* Heart beat lower limit, 8-bit value */

#define mHeartRateUpperLimit_c (201) /* Heart beat upper limit, 8-bit value */

lower limit is 40 and upper limit is 201 so how it is giving 40 to 50 bpm ?

And it seems that sensor data is taken from ADC of KW40, isn't it ? from which ADC input channel the sensor data is expected? because when we open board.c file the function of initialization of adc it is empty.

void BOARD_InitAdc(void)

{

}

Can we define our own ADC channel in this fuction and how?

Re: KW40 Heart rate sensor

isaacavila — Tue, 05 Apr 2016 20:22:31 GMT

Hello Syed,

For USB-KW40 board, heart rate value is taken from a Random Number (using Random Number Generator module) and implements a specific calculation (due this board does not contain a potentiometer). You can look at TimerMeasurmentCallback function at app.c (line 708) where this calculation is made.

In FRDM-KW40 board example, it uses an ADC channel where potentiometer is connected (ADC channel 0). In this example, there is an ADC initialization in board.c file (BOARD_InitAdc function) and heart rate value is taken from potentiometer's value.

I hope this can help!

Regards,

Isaac Avila

topic Re: KW40 Heart rate sensor in Kinetis Microcontrollers

KW40 Heart rate sensor

Re: KW40 Heart rate sensor