Introduction: ATTiny Tea Maker

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About: Am a software engineer by trade. Works mainly with mainframes. Even though I learned Electronics as my degree major and was interested in building stuff, we had a fallout due to lot of failed projects :) Ardui…

This is my very first instructable. I would like to thank all the hobbyists who have shared their knowledge so that it helps us learn and improve.

I was inspired by this excellent instructable https://www.instructables.com/id/littleTea-robotic-... which uses Littlebits to make the tea brewing robot.

My project however, involves ATTiny 85

Parts Required

  • Central Processing Unit :)
  • Framework
    • 3mm plywood
    • Small Screw
  • Utility Knife.. Can't live without this one...
  • Double sided tape
  • A teacup and teabag (of course)

The whole project would cost you around $15 - $20.

Now.. to the works.

Step 1: The Circuit

Hardware

The brain is an ATTiny 85 chip with the PB0 (pin 5) driving the pwm for the servo and the PB1 connected to the buzzer.

If you are using a 5v supply then you can avoid using the 7805 in the circuit (U1, C1 and C2)

J1 - Power

J2 - Power indicator LED

JP3 - Servo motor

J4 - Buzzer

As you would have noticed the buzzer is connected to the Attiny pin and 5v supply. Hence PB1 should be initialized to HIGH for initializing the buzzer during the tea making process. Inorder to get it to buzz you should set PB1 to LOW. You could connect it to Ground and the PB1 and have PB1 go to HIGH for buzzing. I did it this way to help me shrink the circuit a bit.

I would suggest using the prototype board for the circuit assembly. The PCB i had created is bigger than what I could create with the prototype board.

Software

I searched quite a bit for servo libraries for Attiny 85. Got some but didn't do the trick. Then I stumbled accross this one. I honestly do not understand how it works, but it was able to make my servo respond. So I took this one. With a lot of trial and error came up with a fairly satisfactory one for my little project.

I am not happy about the way I have coded it. You might wonder what the hell is this guy doing, but bear with me.

If you guys could improve this code, I would be more than happy.

That said, here is the code

https://github.com/suvinks/Attiny-tea-maker/tree/m..

Step 2: The Robot Framework

Well. Now that we have the brains,will go ahead and make the framework for the robot.

I would suggest that you try making this using cardboard as it saves a lot of time. I just wanted this one to look good so went with wood option

3mm thick plywood sheets you could buy from hobby shops or hardware shops would do the trick. Don't use basswood or balsa, they tear off pretty easy.

The face plate is 2.8 inch X 7 inch

For the Servo and buzzer holes were 7/16 inch drill bit

For the switch and the Led, I used a 1/4 inch drill bit

I didn't make any specific measurements regarding the stand. Just went with my guts on the slot positioning and depth. Had to to a lot of sanding to get them to fit together. All in all it ended up pretty well I believe.

Step 3: Finishing It Up !

Inserted all the components to the slots.

Tightened to servos into position with screws.

Tied up the loose wires and fixed the circuit and the 9v battery with the help of double sided tape.

Then used double sided tape to attach the servo gear to the robot's hand. Used a small screw at the end of robot hand to make it easy to tie the tea bag

Hope at least some of you would try this out and have fun...

Thank you all. Kindly post your feedback in the comments.

Step 4: A 'Timely' Update :)

Was thinking about a useful upgrade for the teamaker. Came up with adding a potentiometer to control the brewing time. I was able to incorporate the change into the existing protoboard itself :)

The new control makes it possible to select the brewing time in fixed 1, 2, 3, 4 and 5 minute intervals. There are no in-betweens, for example you cant select a time say 2.5 minutes :)

Updated code is here

https://github.com/suvinks/Attiny-tea-maker/blob/m...

Please note that the time is not exact. For example 5 minute gives you 4:40 minutes of brewing time and 3 minute option gives 2:50 minutes of brewing time. Didn't have the patience to tinker it to perfection :)

Note

Circuits.io went through an upgrade and now it is crazy hard to edit the circuit and pcb :(. So had to resort to saving the schematic instead of giving you guys a link. Sorry about that.