My new Seeeduino Mega just arrived

I ordered one on the first day they showed stock on hand and it arrived here in Calif in 12 days, packaged well. My first impression was this thing is tiny and thin compared to my 9 pin serial Arduino board. Even with the additional I/O pins avalible, the footprint outline of the board is that of a standard Arduino.

It has four manual switches on the board, a push button for the reset function, and 3 slider two position switches that select 1. 3.3v or 5v operation, 2. power from usb or external, 3. Auto DTR reset on or off. It also has very small LED indicatiors for power on, reset, transmit and receive data on serial port 0 and a pin 13 led. These are very small and hard to see until they light up.

It uses very small connectors for both external power and the USB.

I downloaded Arduino version 16 (I had only used up to 13 till now) and everything worked first try, was able to upload sketches with no problems.

All in all my first impressions are very good, this is a lot of board for $50. If anyone has any questions that I can answer, let me know. Got to run for dinner.

http://www.seeedstudio.com/depot/seeeduino-mega-fully-assembled-p-438.html?zenid=9f6118c193cee9f8b7337d4df91a2eca

Lefty

Pretty cool. I was looking at getting an Arduino Mega but right now this is looking like an even better option :slight_smile:

The Seeeduino folks have posted a schematic for their mega board on their forum:

http://forum.seeedstudio.com/viewtopic.php?f=4&t=378&sid=360d0c0f544c6a10a8e45638e11cd912

Lefty

I'm quite happy with mine too! Though I noticed that it does lack an extra row of holes along the bottom to facilitate breadboard mounting, only has them on the top row (guess they ran out of room).

And I'm a bit nervous about soldering on all the additional headers :-/ Usually my soldering goes ok, but it's not usually done on a $50 board...

Great deal all around! $15 cheaper than a Mega, smaller, and more pins!

No that was on purpose. The extra holes are for if you wish to have all the connectors line up on a .1" X .1" grid for using standard hobby prototyping boards as shields. Only the top row connectors were not aligned to a .1 X .1 grid, so only they require the new holes. It's optional but a nice feature for them to add.

Take your time on the soldering of the extra connectors. Just keep your iron clean and use flux and quality solder. Mine turned out fine. I didn't mount a connector for the 16 extra digital pins that the Seeeduino brings out that the Arduino Mega does not. Those extra I/O pins are not supported in the Arduino IDE code base, so you would have to utilize direct port/pin access to them or write your own additional I/O pin mapping functions.

I'm very pleased with their product. Seeeduino is and builds good quality stuff at great prices.

I'm still trying to figure out the 5vdc - 3.3vdc power switch thing. I first thought it would allow the whole board to run at 3.3vdc. But after looking over the schematic it appears that it just wires to the AVR AVCC power input pin. So that only effects the analog input pins and changes the 0-1023 range to represent 0-5vdc or 3.3vdc range. That's not as useful as I thought it might be.It would allow for more stable calibration on the A/D values as the on-board 3.3vdc regulator would not be subject to the small variations of USB 5 volt power values.

Lefty

I just ordered mine :-)

I didn't mount a connector for the 16 extra digital pins that the Seeeduino brings out that the Arduino Mega does not. Those extra I/O pins are not supported in the Arduino IDE code base, so you would have to utilize direct port/pin access to them or write your own additional I/O pin mapping functions.

Due to the fact that I'm not very familiar with "extra" code for the "extra" pins, are there any sources, examples or information who to do so?

Greg

Due to the fact that I'm not very familiar with "extra" code for the "extra" pins, are there any sources, examples or information who to do so?

Here is a link to a posting on the Seeeduino tech support forum that talks about the Mega pins. http://forum.seeedstudio.com/viewtopic.php?f=4&t=380&sid=e1ec910d0bdd92c25b7969c90ca30796

Here is an example of code to read or write to a few of the 'extra' Seeeduino Mega pins:

/*
* Toggle extended I/O bits 70 and 86 on and off for Seeeduino Mega board
*
* Also added an example of a digital input reading the state of digital pin 71
*/

int switchstate;               // variable to hold value of digital input pin 70

void setup()                    // run once, when the sketch starts
{

  DDRH |= 0x04;                 // sets the digital pin 70 to output, pin 70 is bit 2 of port H
  DDRE |= 0x04;                 // sets the digital pin 86 to output, pin 86 is bit 2 of port E

  DDRH &= 0x7f;                 // sets the digital pin 71 to input, pin 71 is bit 7 of port H
}

void loop()                     // run over and over again
{

  PORTH |= 0x04;                // sets pin 70 high
  PORTE |= 0x04;                // sets pin 86 high
  delay(1000);                  // waits for a second

  PORTH &= 0xfb;                // sets pin 70 low
  PORTE &= 0xfb;                // sets pin 86 low
  delay(1000);                  // waits for a second

  switchstate = PINH & 0x80;   // switchstate is non zero if digital input 71 is high, else it's zero if input 71 is low
}

The 16 'extra' Seeduino Mega digital pins are labled on the back of the board in the format Pxy, where x=port letter and y=bit number.

Lefty

Thanks for the quick reply. That was realy quick :-) I will try this as soon as I have my Seeeduino @ home.

Greg

found this also:

http://www.arduino.cc/en/Reference/PortManipulation

Greg

Nice, but expensive. You can get an arduino mega from ebay for as low as $27. I got a roboduino mega (nice black pcb) for less than 30 euro inc. shipping about half a year ago, and prices are still going down.