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Question: What components  do I need to: load a program to the microcontroller, send three digital signals, three PWM signals, read three digital signals and energize the microcontroller?  (Voting closed: October 03, 2011, 03:00:51 pm)
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Author Topic: Atmega 2560 standalone  (Read 1893 times)
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I would like to know which are the components that an Atmega 2560 needs to make it work as a micrcontroller in which sends three PWM, three digital signals and read three digital signals? I want to load the program through mini usb. The reason I want to know is to design a pcb circuit in Eagle to use less space
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Why such a big part for so few IO? Can do all that with a 328, do it with a promini. Be a lot less expensive too. Plug on a FTDI basic to load it, remove it when done.
Or use a part like the Mini-uino I just had cards made up.
If you search the forum for "very small arduino" with quotes, the thread is one of the first one to be listed.

To answer your question tho, you need 16 MHz crystal, two 22pF caps, three 100nF caps, 10K resistor.
Assumes you bring +5V from an outside stable source, like a wallwart.
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Here's the thread
http://arduino.cc/forum/index.php/topic,69622.0.html
pictures on page 5 I think.
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The absolute minimum is the processor (atmega328p is adequate unless you need the extra flash or RAM of the 2560) and a single 100nF cap between the main Vcc and ground pins. This is if you don't need an accurate clock (so you can use the internal 8MHz oscillator), don't need to program it in-situ, and have a suitable supply in the range 2.7v (or so) to 5v available (e.g. a battery). If you need to program it in-situ, add a 6-pin ICSP header. If you need a more accurate clock, add either a 3-terminal ceramic resonator (accuracy about 0.5%) or the crystal + 2 x 22pf caps. If you don't have a suitable power supply, add a 5v regulator and whatever input and output capacitors that particular regulator needs.
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The problem is that I need memory because I'm going to connect an accelerometer and a Gyro too. But does anyone has a schematic that I can use as a reference?
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Have you looked at the Hardware page? There are schematics there of all the boards. Find the eagle schematic & strip it down.
I am going to make a standalone using one of these and the parts I listed above.

This is a breakout board from these guys

http://www.schmartboard.com/


* AMega2560+Schmartboard.jpg (215.52 KB, 882x713 - viewed 51 times.)
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Thanks!! I came up this design, could someone tell me if this could work?


* Atmega2560.PNG (40.71 KB, 1057x550 - viewed 101 times.)
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Hard to read that, but seems to be on the right track from what I can see.
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this is the eagle schematic

* Control RW3.sch (150.6 KB - downloaded 28 times.)
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Ok, couple of things.
The SCL/SDA lines are pulled up, and you have resistors in series too. May or may not be a problem.

U2, not sure what the part is, but having VDD & VSS connected could be wrong.
Also goes over to U3 - there is no signal name there, so will not be getting any power.

You have a switch, maybe intended for reset? Need to give the signal a name.

DTR from the connector and the FTDI part, that would usually go thru a 100nF cap to the reset pin.
I see a cap on the reset line, but it goes to ground, which would help keep the line quiet, but won't let the FTDI chip reset the uC as part of software download.

Check your power signal names - I see VCC, 5V, REGOUT, 3V.

Hope this helps.
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Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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