Pulse sensor not showing data

Hi everyone,

i have problem with pulse sensor using NodeMCU ESP8266 WIFI , the sensor is not showing the data at all, but instead it showing a space as shown in the figure.

please anyone can help ?

the output

the sensor is not showing the data at all

Where is the sensor supposed to show the data? That statement makes no sense.

The microcontroller can read data from the senor and show that data somewhere.

IF you have written the code correctly. That you get nothing implies that you haven't.