XMAS tree with Arduino controlled leds.

thingiverse

An Xmas tree in OpenSCAD can be found on https://www.thingiverse.com/thing:1214464/files. The holes were modified to accommodate 14 LEDs. The OpenSCAD file is attached for further modification. The hole diameters are 50% of the actual LED diameter, which measures 5mm. When the print is scaled up by 200%, it still fits on a 20x20 cm bed, and the LEDs fit into the holes perfectly. An Arduino Nano controls the open collector outputs of two ULN2003 ICs. The following Arduino sketch serves as a good starting point for programming the LEDs. The LEDs are wired to resistors: Red with 150 Ohms, and Green, Blue, White with 56 Ohms each, for a 5-volt power supply. Here's the code: ```c int L0 = 0; int L1 = 1; int L2 = 2; int L3 = 3; int L4 = 4; int L5 = 5; int L6 = 6; int L7 = 7; int L8 = 8; int L9 = 9; int L10 = 10; int L11 = 11; int L12 = 12; int L13 = 13; int t=20; void setup() { pinMode(L1, OUTPUT); pinMode(L2, OUTPUT); pinMode(L3, OUTPUT); pinMode(L4, OUTPUT); pinMode(L5, OUTPUT); pinMode(L6, OUTPUT); pinMode(L7, OUTPUT); pinMode(L8, OUTPUT); pinMode(L9, OUTPUT); pinMode(L10, OUTPUT); pinMode(L11, OUTPUT); pinMode(L12, OUTPUT); pinMode(L13, OUTPUT); } void loop() { digitalWrite(L0, LOW); delay(t);digitalWrite(L0, HIGH); //star led digitalWrite(L1, HIGH); delay(t);digitalWrite(L1, LOW); digitalWrite(L2, HIGH); delay(t);digitalWrite(L2, LOW); digitalWrite(L3, HIGH); delay(t);digitalWrite(L3, LOW); digitalWrite(L4, HIGH); delay(t);digitalWrite(L4, LOW); digitalWrite(L5, HIGH); delay(t);digitalWrite(L5, LOW); digitalWrite(L6, HIGH); delay(t);digitalWrite(L6, LOW); digitalWrite(L7, HIGH); delay(t);digitalWrite(L7, LOW); digitalWrite(L8, HIGH); delay(t);digitalWrite(L8, LOW); digitalWrite(L9, HIGH); delay(t);digitalWrite(L9, LOW); digitalWrite(L10, HIGH); delay(t);digitalWrite(L10, LOW); digitalWrite(L11, HIGH); delay(t);digitalWrite(L11, LOW); digitalWrite(L12, HIGH); delay(t);digitalWrite(L12, LOW); digitalWrite(L13, HIGH); delay(t);digitalWrite(L13, LOW); } https://youtu.be/VYAfNfvDHbo ```