Go Down

Topic: Atmega 2560 standalone (Read 2093 times) previous topic - next topic

EDPACA

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

CrossRoads

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.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

Here's the thread
http://arduino.cc/forum/index.php/topic,69622.0.html
pictures on page 5 I think.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

dc42

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.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

EDPACA

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?

CrossRoads

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/
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

EDPACA

Thanks!! I came up this design, could someone tell me if this could work?

CrossRoads

Hard to read that, but seems to be on the right track from what I can see.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

EDPACA

this is the eagle schematic

CrossRoads

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.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Go Up