Update samp_spd

samp_spd

 // Reference: https://forums.raspberrypi.com/viewtopic.php?t=368639
+//https://www.hackster.io/AlexWulff/adc-sampling-and-fft-on-raspberry-pi-pico-f883dd
 
-#include <Arduino.h>
+#include <Arduino.h> //https://github.com/arduino/Arduino/blob/master/hardware/arduino/avr/cores/arduino/main.cpp
 
 int led =25;
 UART pc1(4, 5, NC, NC);