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Connecting 2 Tinusaur Boards Gen:4 mk-II

How to connect 2 Tinusaur boards with Shield boards on them using 3 wires?

This tutorial is written specifically for Tinusaur Boards, generation 4, for the latest versions of the Shield EDUx3IO and Shield LEDx2 boards (a.k.a. mk-II), manufactured and sold in 2024 and onwards. To make sure you have the same ones – check the images.

Hardware

We will need 2 pcs Tinusaur boards, obviously.

We will also need 2 additional boards – Shield EDUx3IO and Shield LEDx2.

The setup will be similar if we substitute Shield LEDx2 with Shield LEDx3.

We will need 3 jump wires (also sometimes called Dupont cables) of a female-to-female type.

NOTE: The color of the cables does not define the purpose or function of the wires.

Also, for clarity, the pair of a Tinusaur main board and a Shield EDUx3IO we will name K1. The pair of a Tinusaur main board and a Shield LEDx2 we will name K2.

Software

The software part, or how to program them, is covered in another tutorial.

Setup for K1

Let’s first insert the Shield EDUx3IO board on top of the Tinusaur main board. There are a few headers for external connections, and one of them is a 3-pin angle header marked as COM, DBG, or PB3, depending on which modification of the board we have. We will use this header to communicate with the other board via 3 wires.

This is IMPORTANT. We have to locate the correct header to use for the connection.

Setup for K2

The setup is similar to the other board.

Let’s first insert the Shield LEDx2 (or LEDx3) board on top of the Tinusaur main board. There are a few headers for external connections, and one of them is a 3-pin angle header marked as COM, DBG, or PB3, depending on which modification of the board we have. We will use this header to communicate with the other board via 3 wires.

This is IMPORTANT. We have to locate the correct header to use for the connection.

Header Pins Assignment

This is applicable for both of the boards – K1 and K2.

This is VERY IMPORTANT. We must identify what function each of the 3 pins has for this to work correctly. Incorrect use of the pins might DAMAGE your boards.

The functions of the pins are defined as follows:

  • GND – Ground, or (-) negative power supply pole.
  • SIG – Signal, or PB3, the middle pin.
  • VCC – Voltage, or (+) positive power supply pole.

Connecting the 2 Boards

This is IMPORTANT. We MUST connect the ground (GND) wires together; the signal (SIG) wires together; and the Voltage (Vcc) wires together.

This is what the connected boards should look like.

Cables come in various lengths and colors. Yours might be different from those in the picture.

Main Board Button

The Main Board button could be connected to either the PB3 port or to the RST (reset) line of the microcontroller ATtiny85. This function is switched by the header 2×2, and the jumper cap that we put on it.

The setup for communication between 2 boards also uses the PB3 port.

This means that when we want to create such a setup, we will not be able to use the button programmatically via port PB3. However, we can still use the button as a reset.

This is a limitation that is not easy to avoid, given the small number of pins on our ATtiny85 microcontroller.

Such limitation could be avoided if we use another pin, different from PB3. In that case, we would have to be more knowledgeable about programming and manipulating the input/output ports of the ATtiny85 microcontroller. The details about how to do that are the subject of a different tutorial.

Another “side-effect” is that if we use the button on port PB3 and the communication capabilities, pressing the button could be used for testing and debugging purposes, as it will cause the PB3 port to go to 0 (zero) when pressed.

Power Supply

In this particular setup, which is conditioned by the type of shield boards we use, the voltage sources (Vcc) and the common ground (GND) of the 2 boards are connected together. That implies the following:

  • We can provide power only for one of the boards, the other one will get the power through the 2 wires – Vcc and GND.
  • IMPORTANT: if we decide to provide separate power for both boards, it must be the same voltage. For example: If one power source is 5 Volts, the other cannot be 3 Volts. Having power sources with different voltages might damage the power supplies, the boards, or both.

Conclusion

Connecting 2 Tinusaur Boards is easy and straightforward. It allows boards to exchange signals, which is the subject of another tutorial.

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Copyright © 2024 Tinusaur. All Rights Reserved. Authors: The Tinusaur Team
License: CC-BY-SA-3.0, Creative Commons Attribution–ShareAlike License.
Retain in your derivative work a note about the original authors and a link to the Tinusaur website.

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