Adding a "millis blink" code to existing servo code

I am a novice when it comes to coding Arduino, however I do love the communities and the help online for whatever project you may find. I am in the process of making a raise and lower action with a servo using Bluetooth and an android app (which I have working as well as with VarSpeedServo library for some speed control). I did get this working and in the process learned a bit of android code as well. I also successfully added a LED that does read the sent data and turns on when it is told to.
The problem I face now is to add a millis flash/strobe LED setup code (which I found online and learned from) to do the same, I really don’t like the idea of using delay() at all. I currently added a push button (which simply gets pressed by the arm in lowered position (0)) and got that code working (could probably be simplified but working is good enough for me since I am a novice lol). I have tried various ways to get the millis code snippet to act on the data sent by the bluetooth serial instead of a pushbutton… but I cannot get it to work. It seems to me that the timer for millis() is paused in the loop somehow as I lower the arm it only runs part of the code, lights one led and then if I raise the arm it goes out, next turn I lower the arm the 2nd led in the millis snippet comes on… I have tried various ways to get this to work but I am at a loss here… I am sure it is something pretty basic I am missing and I could just keep using the switch but I like things to be simple if possible :slight_smile: Any help would be appreciated.

Here is the current code I am using (sorry for the horrible state of it as I learn as I try):

#include <VarSpeedServo.h>    // Variable speed servo library
#include <SoftwareSerial.h>   // Include library for software controlled/assigned serial pins
//#define bluetooth Serial      // Define bluetooth to use Arduino TX/RX pins through hardware setup
#define RED 0x0
#define RED2 0x1
byte whichLED = RED;
VarSpeedServo myservo;                              // variable servo speed library defined to myservo
const int BtnPin = 2;                               // Arm button pin
const int MvPin =  3;                               // Mainviewer LED pin
const int RedLed1 = 4;                              // First Red Blink/Strobe LED Pin 
const int RedLed2 = 5;                              // Second Red Blink/Strobe LED Pin
const int bluetoothTx = 10;                         // Software assigned pin for TX channel
const int bluetoothRx = 11;                         // Software assigned pin for RX channel
SoftwareSerial bluetooth(bluetoothTx, bluetoothRx); // Define software controlled TX/RX pins

// Variables that can change
int buttonState = 0;                                // Variable for reading the Arm button status
int pos = 0;                                        // Servo position to turn on Mainviewer LED

// State variables for the LEDs
byte Red1_State = LOW;
byte Red2_State = LOW;
// Some delay values to change flashing/strobe behavior
unsigned long switchDelay = 1000;
unsigned long strobeDelay = 10;
// Seed the initial wait for the strobe effect
unsigned long strobeWait = strobeDelay;
// Variable to see when we should swtich LEDs
unsigned long waitUntilSwitch = switchDelay;  // seed initial wait

void setup()

  pinMode(RedLed1, OUTPUT);   // Define pinmode for Red LED 1
  pinMode(RedLed2, OUTPUT);   // Define pinmode for Red LED 2
  pinMode(BtnPin, INPUT);     // Define pinmode for Arm Button
  pinMode(MvPin, OUTPUT);     // Define pinmode for Blue/White LED for mainviewer
  myservo.attach(9);          // Arduino pin for servo control
  Serial.begin(9600);         // Setup usb serial connection to computer
  bluetooth.begin(9600);      // Setup Bluetooth serial connection to android

void loop()

  // Read from bluetooth received data to move servo
  if(bluetooth.available()> 0 ) 
      int servopos =; // get the received data
      Serial.println(servopos); // print to serial USB monitor
      myservo.write(servopos,50,true); // move the servo to the received data location
            // LED Control depending if arm is up or down
            if (servopos == pos) 
            // read servo pos and turn Blue LED on:
            digitalWrite(MvPin, HIGH); // Mainviewer LED
            // read servo pos and turn Blue LED off:
            digitalWrite(MvPin, LOW); // Mainviewer LED
                //Red Blink/Strobe LED's controlled by a HIGH state button
                // check if the pushbutton is pressed.
                buttonState = digitalRead(BtnPin);
                // if it is, the buttonState is HIGH:
                if (buttonState == HIGH) 
                        {//LED Flash or Strobe Start
                        digitalWrite(RedLed1, Red1_State);     // each iteration of loop() will set the IO pins,
                        digitalWrite(RedLed2, Red2_State);    // even if they don't change, that's okay
                        // Toggle back and forth between the two LEDs
                        if ((long)(millis() - waitUntilSwitch)>=0) {
                        // time is up!
                          Red1_State = LOW;
                          Red2_State = LOW;
                            whichLED = !whichLED;  // toggle LED to strobe
                            waitUntilSwitch += switchDelay;
                        // Create the stobing effect
                        if ((long)(millis() - strobeWait)>=0) {
                        if (whichLED == RED)
                          Red1_State = !Red1_State;
                        if (whichLED == RED2)
                          Red2_State = !Red2_State;
                            strobeWait += strobeDelay;
                        }//LED Flash or Strobe End 
                          // turn LED off:
                          digitalWrite(RedLed1, LOW);
                          digitalWrite(RedLed2, LOW);

if ((long)(millis() - strobeWait)>=0) {
Don't use (long)

Will this not always be true i.e. unsigned math :wink: