Is there anything special about this board? No! Absolutely nothing.
Even though the Tinusaur is a very simple thing it has its advantages as well as disadvantages that need to be addressed.
It is a platform that is simple and easy to understand for everyone – perfect for a quick start and in learning how to create things.
The board consists of the minimum required components for its micro-controller to function properly. There are no missing parts that could save on space and cost but may impact stability. There are no extra components that you may not always need.
- There are benefits of choosing the Tinusaur over some other similar projects.
- There are of course things that are not perfect with the Tinusaur and we must mention them a.
Still interested …
More details are laid out in the Pros and Cons page.
In this post are discussed some of principals used while designing this board.
Size and form factor
The goal of making this board is not to have a smaller or the smallest PCB that runs on ATtiny. The goal is to have a board that could be used for prototyping simple projects as well as fitting reasonable small (or large, depending on the view) circuits on an additional shield board.
There are 2 header – one 2×4 – H1 and another one 2×5 – H2.
The idea is that all the outer pins are GND while all the inner pins are connected directly to the MCU. The longer header H2 has its top-left pin connected to the Vcc like the 2nd-row one on the left. That gives us one more power source wire.
This board could work with the smaller Atmel AVR ATtiny controllers such as ATtiny 25/45/85, ATtiny13 as well as most of their variations – as long as they are in DIP-8 case.
The programming is done through the standard 10-pin ISP connector using any compatible AVR ISP programmer. On the diagram below it is marked as PC.
The connector is placed on the board in such a way so it could be chopped off if not needed and make the board little smaller. The programming probe, marked as PP on the diagram below, has holes that could help in the cutting. In case you need to connect the board to a programmer again at later time you can solder some wires to what’s left of the probe.
Technical parameters: 2 layer board of 0.90×1.40 inches (22.96×35.66 mm).
There are 4 mounting holes marked as MH on the diagram below.
During the development the board could be powered through the ISP programmer.
External power source could be connected to the board through a jumper marked as PS on the diagram below.
There is an optional button-cell battery mount on the back of the board, marked as BM on the diagram below. The battery could be switched on and off using the jumper that is marked as BS on the diagram.
There are 4 areas that a Tinusaur board could be divided to: A1, A2, A3, A4. That is applicable for the actual Tinusaur main board as well as any shield boards one could produce.
A1, the bottom part of the board:
- this is the area where the RESET button is placed on the main board.
- for a shield board that area could be used to put some components and produce a simple circuit.
A2, the mid of the board – heads:
- there are 2 header – one 2×4 and another one 2×5, they are different for a reason.
- on the main board, between the headers, is placed the MCU.
- on a shield board, between the headers, could placed a 8-pin chip or other components.
A3, the top part of the board:
- there are the minimum required components for the MSU to work – 2 capacitors for the power source and one pull-up resistor for the RESET.
- jumper for external power.
- jumper to switch on/off battery.
A4, tip of the board:
- standard ISP programming connector.
A5, the other side of the board:
- there is optional cell-button battery mount.
The new prototype PCBs just arrived from OSHPark – great quality as usual.
I noticed that there are only few things that I may change before call it official: slightly move some components around so they fit better and become easier to solder; add one jumper for switch on/off the optional button cell battery on the bottom of the board; make some pads and holes larger; … and few other things.
I have finally managed to finish the first version of the schematics and PCB‘s and to order the first 3 pieces. This work is based on some previous experiments and designs.
The schematics is nothing special – it is the well known minimal configuration for the ATtiny plus just few addition components – some of them optional.
The required components are the 2 capacitors between Vcc/GND and the 10K resistor on the RESET wire.
There is RESET push-button connected to the micro-controller.
The micro-controller connects to the outside world through 2 headers – H1 an H2. They are in two different sizes for number of rasons: first – to have more connections available for wires, and second – to make sure we won’t mistake H1 and H2.
Next to the headers there is 1×2 connector for external power source.
There is an optional battery for application where built-in power source is needed.
The PCB is a fork of my previous work on a simple header board.
There are 4 holes in the corners in case the board should be fixed to another object.
On each side of the IC there are 2-row headers – on 2×4 and the other 2×5.
External power source connector is put along with the H2 header.
The ISP connector is at the top of the board. Between it and the rest of the board there is 1×6 header-like probe – this could be used for testing as well as for easier cutting off the ISP part of the board in case is not (or no longer) needed.
The pads for the optional battery are on the bottom.
The size of the board is approximately 24×36 mm.