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How to use a new electronics board for dummies: MegaPi example

Powerful Arduino Mega compatible control board

 

Now that we have a new electronics board so powerful and versatile as the MegaPi we say: how can I get something out from this little beast? Easy with this review!


Yes, we don’t know anything about the board the moment we start, and we want to create some cool robots, 3D printers or any other crazy project. How can we pass from ignorance to mastery. Simple steps is the key. Let me show you my recipe, which is very known in Engineering but don’t be scared. It also has the ingenuity we need.


They are only five steps in brief:

  1. Power supply.

  2. Outputs and Inputs.

  3. Configuration or modes of work. Programming.

  4. Tests.

  5. Your project.


  1. Power supply.

The first thing you need to make an electronics device to work is power. The right one, enough of it. If you only give power, you have at least an Power on LED on. Little big success!


How to achieve it? Just check the specs!


Yes, I know we don’t check specs unless we are totally lost… which is the case, otherwise you don’t need them, right? Where to get the specs: the manufacturer website is usually the key place. We go to the main MegaPi website… http://makeblock.com/megapi


And Boom! Here it is:

 

1.Power supply-specs

Ups! Input Voltage and Operating Voltage sounds very similar, but one is DC 6 V to 12 V, and the other is DC 5 V… so which one can we need to feed to the board? Don’t panic! Let’s see the connectors on the board first:

(Picture also from the MegaPi webpage from the manufacturer)


2.Power at the main board MegaPi


Here we see High-Power DC Supply (6-12 V).


That means that’s the high power for motors that we drive from the board…? What about the 5 DCV we saw before?


Let’s check the schematics to get more information. They are linked from the main page mentioned before User Guide: Learn: http://learn.makeblock.com/megaPi/ here: 7.Schematic Circuit Diagram


After checking both, you locate the High-Power DC connector in the second schematic page.


Don’t be afraid, we are looking for the main component: the connector, and the power supply it gives:


3.Analysys of power input for MegaPi

 

As you see the connector for High-Power DC (JP1) at the left goes to a switch with two positions. Pin 3 of the switch goes to nothing, imagine what: it’s for power off state of the board. Nothing gets power.


The other pin of the switch (for switch ON): 2, goes to V+ which goes to the motors. To double check look for that V+, at the top of the same second schematic:


4.Detail on Motor power at MegaPi


Finally but not less important, we see the line of power of V+ goes to a diode (D3), a fuse, and then to an integrated circuit labeled as TPS54331. A Google search gives us directly the Texas Instruments webpage of that device: it’s a “step down” voltage converter. It converts a “high” voltage source to a “low” voltage one. In our case to 5 V DC...

 

5.5 V DC Power supply

 

needed for the Arduino microcontroller, as we see in the first schematic:


6.5 V DC Power supply to Arduino



So the summary now of things we know is:

  1. we can power the whole board from DC 6 to 12 V,

  2. and it has a switch to turn it ON and OFF with an LED for Power status.

  3. It gives also direct power to motors.

  4. And has its power supply of 5 V DC for the microcontroller.


In the next part we'll see intputs and outputs to handle our next robot or creation. Do you want to participate? Enroll now in the review of the MegaPi here when still available!