digispark.suilent_activity_emulator.ino

#include "DigiKeyboard.h"

/*
  You can also change vendor of device =)
  path ~/Library/Arduino15/packages/digistump/hardware/avr/1.6.7/libraries/DigisparkKeyboard/usbconfig.h

  Below there are values for Apple Keyboard
  #define USB_CFG_VENDOR_ID 0xac, 0x05
  #define USB_CFG_DEVICE_ID 0x02, 0x02
  #define USB_CFG_VENDOR_NAME     'A','p','p','l','e',' ','I','n','c','.'
  #define USB_CFG_VENDOR_NAME_LEN 10
  #define USB_CFG_DEVICE_NAME     'K','e','y','b','o','a','r','d'
  #define USB_CFG_DEVICE_NAME_LEN 8
*/

/*
   silent activity emulator (without key-bases side effects)
*/

#define LEFT_CTRL 0xe0

//use led as activity indicator
#define LED_PIN  1

void setup() {
  pinMode(LED_PIN, OUTPUT);
  randomSeed(analogRead(0));
  digitalWrite(LED_PIN, LOW);
}

void loop() {
  //turn light on
  digitalWrite(LED_PIN, HIGH);

  //use magic Ctrl's combination in order to avoid side-effects
  DigiKeyboard.sendKeyStroke(LEFT_CTRL, MOD_CONTROL_LEFT);

  DigiKeyboard.delay(100);

  //turn light off
  digitalWrite(LED_PIN, LOW);

  //random delay between 5s and 20s
  DigiKeyboard.delay(random(5110, 20201));
}