[Q] Create a timer to control a customized module

[jafarniknam]

Hi . I used this BTT firmware to control a laboratory robot (not a 3D printer) and added a new option to the display menu to control a UVC sanitizer. In this menu, it is necessary for user to specify the value of timer and then the display sends the G-code to the motherboard for the UV lamp relay to turn on (M42 P(relay pin) S( LOW or HIGH) : pin status G-code) .
At this point, it is necessary for a timer to start counting and to turn off the UV lamp after the timeout (display sends G-code to the motherboard for turning the relay off)
In your opinion, what is the best way to create a timer in this section?
My idea is to send start printjob timer G-code and get feedback from the motherboard (using commands M75 & M77 & M31)

motherboard : MKS GEN V1.4
Firmware : marlin 2.0 bugfix
display : MKS TFT32 V4.0
display Firmware : modified BIGTREETECH-TouchScreenFirmware

This is the first code I've written to test this part and it worked properly:

`
void menuUVsanitizer(void)
{
KEY_VALUES key_num = KEY_IDLE;
bool timeChanged = true;
menuDrawPage(&loadUnloadItems);
timeReDraw(inputUvTime);
while (infoMenu.menu[infoMenu.cur] == menuUVsanitizer)
{
key_num = menuKeyGetValue();
switch (key_num)
{
case KEY_ICON_0: // Decrease time
if(inputUvTime > 0)
{
inputUvTime--;
timeChanged = true ;
}
break;

    case KEY_ICON_3:  // Increase time 
      if(inputUvTime < 20)
      {
        inputUvTime++;
        timeChanged = true;
      }
      break;

    case KEY_ICON_4:  // start UV procedure 
      mustStoreCmd("M42 P50 S255\n");
      break;

    case KEY_ICON_5:  // stop UV procedure 
      mustStoreCmd("M42 P50 S0\n");
      break;

    case KEY_ICON_7:  // back
      infoMenu.cur--;
      break;

    default:
      break;
  }
  if(timeChanged == true)
  {
    timeReDraw(inputUvTime);
    timeChanged = false;
  }

loopProcess();

}
}
`

[jafarniknam]

@bigtreetech can you help me , please ?
@kisslorand
@darkspr1te