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LED Pod Strobe Flasher


Jeremy from Pololu suggested I join up and post this up so here it goes!

First off, I am relatively new to coding. I am an avionics guy by trade and understand board level components, but had not touched a micro-controller up until a few months ago when I was assigned as part of a design team to develop a smart battery charger/tester for emergency light batteries on an aircraft. Our design was using an Arduino Mega. That set me off into the “self education” mode. So that being said, I have been trying to apply some of what I am learning to something a little more fun.

I am working on a flasher that will control multiple strobe pods. My second job includes sales and installation of off road vehicle accessories so I want to do something useful for safety lights for off road trucks. What I have running so far is pretty simple. It’s strobing two 18W LED PODS. I’m using the Arduino to fire two TIP32’s to control the strobes. I admit that I had to grab the initial code from James at CMIYC because I am having some difficulty grasping the milis() function.

Future plans that I want to develop include adding two to four more outputs, having selectable modes from continuous on, to a chasing pattern that would fire the strobes sequentially, and a separate project that would control just a single light bar. (Higher amp draw so looking at doing that with a STP40NF10L MOSFET. I’ll also be moving this to the 32U4 so I can make the final package much smaller.

Feel free to offer up any suggestions, criticism, etc.

Here is a quick video of what I have thus far:

And the code that I used to get started:

10. // English for which LED to Strobe 11. #define RED 0x0 12. #define BLUE 0x1 13. 14. // Variable to track which LED is on 15. byte whichLED = RED; 16. 17. // Where are the LEDs connected? 18. const int LED_Red = 7; 19. const int LED_Blue = 11; 20. 21. // State variables for the LEDs 22. byte Red_State = LOW; 23. byte Blue_State = LOW; 24. 25. // Some delay values to change flashing behavior 26. unsigned long switchDelay = 250; 27. unsigned long strobeDelay = 50; 28. 29. // Seed the initial wait for the strobe effect 30. unsigned long strobeWait = strobeDelay; 31. 32. // Variable to see when we should swtich LEDs 33. unsigned long waitUntilSwitch = switchDelay; // seed initial wait 34. 35. 36. void setup() { 37. pinMode(LED_Red, OUTPUT); 38. pinMode(LED_Blue, OUTPUT); 39. } 40. 41. void loop() { 42. digitalWrite(LED_Red, Red_State); // each iteration of loop() will set the IO pins, 43. digitalWrite(LED_Blue, Blue_State); // even if they don't change, that's okay 44. 45. // Toggle back and forth between the two LEDs 46. if ((long)(millis() - waitUntilSwitch)>=0) { 47. // time is up! 48. Red_State = LOW; 49. Blue_State = LOW; 50. whichLED = !whichLED; // toggle LED to strobe 51. waitUntilSwitch += switchDelay; 52. } 53. 54. // Create the stobing effect 55. if ((long)(millis() - strobeWait)>=0) { 56. if (whichLED == RED) 57. Red_State = !Red_State; 58. if (whichLED == BLUE) 59. Blue_State = !Blue_State; 60. strobeWait += strobeDelay; 61. } 62. }


Hey, Nick!

Welcome to our forum. Thanks for sharing your project. Can’t wait to see it in action on the vehicle.

Using millis() allows you to implement time dependent functions, such as turning on a light for a specific duration of time, without blocking the controller from performing other tasks. In your case, it looks like you are not performing other tasks when the lights are strobing so you could have used the delay() function. For more about their differences, you might find the Blink Without Delay Arduino Example helpful.

- Jeremy


Thanks man. Work on it right now is limited due to my day job workload but will read up on the tutorial you posted as I can. I’ll keep you posted.