Now that we have a working circuit, we should start to write down our sketch to collect data from the light sensor. Then we should analyze these results and think about an algorithm to transform readings into a heartbeat counter. We should start a new sketch and add the following steps:
Add the following declarations on the top of the sketch:
#define SENSOR A0 #define HEARTBEAT_POLL_PERIOD50 #define SECONDS 10 constint TIMESLOTS = SECONDS * 1000 / HEARTBEAT_POLL_PERIOD; int sensorReading = 0;
We define the object-like macro
A0value that is the pin we will use for the analog read. We set
HEARTBEAT_POLL_PERIODto specify how many milliseconds the microcontroller should wait between consecutive sensor readings. With the
SECONDSparameter, we define the seconds that should elapse before we use collected data to process and estimate the heart rate. Indeed, we multiply
1000to convert this value into milliseconds and then we divide it by the...