Attiny85 small useless-box

Small and configurable useless box controlled by ATtiny85 uC. Just one servo motor for movements and there are also lights! If you want there are gerber files for a custom PCB board.

Project name:

Small Useless Box

 

Description

Compact (76x50x66 mm) useless box controlled by an ATtiny 85 uC, powered by 9V battery.

 

Functions

• Useless box with one servomotor and colorful LEDs
• Programmable behavior
• Powered by 9V battery
• Custom PCB available

 

Hardware and Software Used

Hardware:

3D printed PLA components

• 1 x servomotor RG90 or similar model as MG90
• ATtiny85 micro controller
• 2 x 5mm led (fast flashing colors)
• 1 x switch button
• 2 x push button
• custom PCB with SMD and PTH components

Software:

• Tinkercad has been used to draw all parts
• Prusa Slicer has been used to obtain gcode files
• Arduino IDE has been used for the firmware
• EasyEDA has been used ti draw schematica and create Gerber files

 

Wiring Diagram

Board schematics and footprint

 

BOARD BOM
ID	NAME	DESIGNATOR	FOOTPRINT	Q.TY
1	0.47u	C1	C0805	1
2	22u	C2	C0603	1
3	470u	C3	CAP-D8.0×F1.5_BIPOLAR	1
4	0.1u	C4	C0603	1
5	1N4007W	D1	SOD-123_L2.8-W1.8-LS3.7-RD	1
6	SERVO MALE HEADERS	H1	HDR-TH_3P-P2.54-V-M-1	1
7	BTN_CONN MALE HEADERS	H2	HDR-TH_3P-P2.54-V-M-1	1
8	LED-TH-5mm	LED1, LED2	LED-TH_BD5.0	2
9	BJT NPN (TO-92)	Q1	TO-92-BJT NPN	1
10	22k	R1	R0603	1
11	180R	R2	R0603	1
12	1k	R3,R4,R5,R6	R0603	4
13	LM2940IMP-9.0/NOPB	U1	SOT-223-4	1
14	DIP8-SOCKET	U2	DIP-8	1

NOTE: R3, R4, R5, R6 are not mandatory for this project. They are optional components to set pull-up or pull-down aux signal to the uC.

Other electronic components required but not mounted directly to the board:

• 1 x servomotor SG90 or similar.
• 1 x switch
• 1 ATtiny85 uC
• 2 x 3 pin female headers
• 1 x 9V battery plug connector
• wires

Code

/* 
 Firmware for small ATtiny85 useless box
 WARNING: Set uC internal clock at 8MHz to run properly
 If Servo library is installed to libraries, then that version (which         doesn't support ATtiny parts)
 will be used instead of the one included with the core, which does. To get around this,
 include  Servo_ATTinyCore.h instead - this will always use the version that came with core.
*/
#include <Servo_ATTinyCore.h>
#define servo_pin 0
#define btnA_pin 1 // Internal switch
#define btnB_pin 2 // External switch
#define led_pin 4
#define min_ang 5
#define max_ang 78
#define turn_off_time 5000
Servo myservo;  
bool A, B, S;
unsigned long t0;
int pos = 0;    // variable to store the servo position
long rnd;
void setup() {
  pinMode(btnA_pin, INPUT_PULLUP); // A low at rest
  pinMode(btnB_pin, INPUT_PULLUP); // B high at rest
  pinMode(led_pin, OUTPUT);
  digitalWrite(led_pin, LOW);
  randomSeed(analogRead(4));
  S=0;
}
void loop() {
  A = digitalRead(btnA_pin);
  B = digitalRead(btnB_pin);
  if (!A && B){
    S = 1;
    digitalWrite(led_pin, HIGH); // turn on LEDs
    myservo.attach(servo_pin);
    rnd = (random(0, 200))*10; // add chaotic behaviour
    delay(rnd); 
    turnOff();
digitalWrite(led_pin, LOW);
t0 = millis();

  }
  if (millis()-t0 > turn_off_time && S){
    myservo.detach();  // for energy saving
    S = 0;
    t0 = millis();
  }
}
void turnOff(){
  int i = 0;
  for (pos = 30; pos <= max_ang; pos += 4) {
    myservo.write(pos);
delay(20);
}
  for (pos = max_ang; pos >= min_ang; pos -= 2) { 
    myservo.write(pos);
delay(5);
}
  for (i = 0; i < 10; i++) { 
    myservo.write(min_ang);
delay(5);
}
}

Printing Instructions

Filament: PLA Layer height: 0,3 mm Infill: 20% Supports: form build plate only Note: disable supports inside the holes for screws or pins.
Filament: PLA Layer height: 0,3 mm Infill: 20% Supports: everywhere Note: disable supports inside the holes for screws or pins.
Filament: PLA Layer height: 0,3 mm Infill: 20% Supports: form build plate only Note: disable supports inside the holes for screws or pins.
Filament: PLA Layer height: 0,3 mm Infill: 20% Supports: form build plate only Note: disable supports inside the holes for screws or pins.
Filament: PLA Layer height: 0,3 mm Infill: 20% Supports: form build plate only Note: disable supports inside the holes for screws or pins.
Filament: PLA Layer height: 0,3 mm Infill: 20% Supports: form build plate only Note: disable supports inside the holes for screws or pins.

Assembly Instructions

Assemble all the components on the PCB (Wire to the switch should be about 33 mm long) Mount the programmed ATtiny85 on the socket Bend the Servo headers as see in the picture above
Insert the 2buttons on the switch lid (may be annoying) Insert the switch lever and secure it with a 2x16 mm pin Solder the 3 pin female headers wires as required. Verify correct functionality of the switch (may be very annoying!)
Mount the finger on the servo arm accessories (trim if necessary) and fix with a screw.
Mount the finger on the servo motor using the arm screw
Insert the servo on the proper housing. WARNING!!! Make sure the servo is in it 0 position when the finger is completely down. Plug the servo connector in the board’s servo headers. Carefully insert the board on the main case and make sure it fits well (this can be annoying too)
Using a tweezers or pliers insert the power switch in the proper position Lock the power switch with a couple of M2x4 screws
Using a tweezers or pliers insert the LED on their housing in the moving lid Prior to hinge assembly use an 2mm drill tip to round the hinge's holes.  Insert 2 x M2x20mm pin in the lid’s hinge as shown in the picture and push them all the way into the hinge
Secure the servomotor with the motor holder (you can use screws to lock it) Plug the switch’s lid on the board headers for the buttons (respect the orientation)
Secure the switch lid wit 3 x M2x6 screws Plug the 9V battery to the connector and insert into the housing
Close the battery lid and secure it with a M3x10 screw

Demo and Usage Instructions

• Power up.
• Switch on.
• Repeat until enough useless work has been done or low battery.
• Power down.

Photos and Videos