USB laptop hand warmer

This device collects warm air from a laptop and directs it to the vicinity of the hands for warmth. The controller is based on the Arduino 32u4 development board.
It can be powered directly via USB, and an additional USB female connector is provided for independent power supply. Fan speed is controlled via an HTML webpage, accessible using a WebSerial-enabled browser (e.g., Chrome or Edge). The speed can be adjusted by scrolling through the page.
 
 
 
Using an Arduino Pro Micro (32u4) as the main controller, the code is as follows:
 
#define PWMCONTROLPIN 6 void setup() { pinMode(PWMCONTROLPIN, OUTPUT); digitalWrite(PWMCONTROLPIN, 20); Serial.begin(115200); Serial1.begin(115200);}
// WebSerial sends data in string form // For example: "123"+0x0A
String sVal=""; void loop() { while (Serial.available()) { char c=Serial.read(); if (c!=0x0a) { sVal=sVal+c; } else { analogWrite(PWMCONTROLPIN, sVal.toInt()); Serial.println(sVal.toInt()); Serial1.println(sVal.toInt()); sVal=""; } Serial.println(sVal); The control terminal
 
uses Web Serial, so it appears as a webpage; the attached file is USBFanCtrl.zip.