ATMEL Mega1284P evaluation board avalible

Why DIP vs SMD?

Just so one could develop the sketch on the board and then pull the chip for a standalone application. No big deal I guess, just more convenient then directly programming the dip in it's standalone home.

Lefty

I think that's one major advantage of the 1284 - you can get it in DIP :slight_smile:

Looks like it could fit, have to see if its routable or not. Kinda jammed up by the SD card driver & RS232 driver.
Still no JTAG/ICSP headers.

mowcius:
I think that's one major advantage of the 1284 - you can get it in DIP :slight_smile:

That was my whole point. I homebrew some of my stuff, but only in DIP version, too old and tired to do major smd hand soldered layouts.

Another question is the 1284 and 644p pin compatable in the DIP versions? An arduino board that could utilize DIP 644p and 1284 would open my wallet, assuming the IDE software could be made to work with it by mear mortals like myself. :smiley:

EDIT: Answered my own question by reviewing datasheets: 644p and 1284 are pin compatible in 40pin dip version at least.

Lefty

For my own personal interest, DIP vs SMD isn't a big deal. I think conceptually I like the idea of DIP as it does afford more flexibility. But, as to the RS-232, for my own (current) need, just some form of header would be even better, as I need (well, want) to get to an RJ-11.

I'd ditch the DB9 and use a header. You can get IDC DB connectors that use ribbon cable so they still look neet and can easily be mounted remotely, makes fitting the board into an enclosure easier and you can swap from male to female without desoldering a connector.

That should route easily (manually of course :)), using the DIP doesn't really make it worse because you can run 2 lines between pins, whereas the TQFP is basically a no go zone for one layer.

Please get rid of the huge USB connector and use a mini B.

Add a jumper (not a solder bridge) for the auto reset so it can easily be disabled.

The headers at the end of the chip are pretty close, Ok if you use a screw driver to remove the chip from the other end but may get in the way of a chip puller.

Crystal too close to the chip, especially with a socket.

I'll shut up now, I guess it's just a quick mock up but thought I'd highlight a couple of things anyway.


Rob

Well, I got the schematic redone for the DIP, added solder bridge fields to route I2C or A4/A5 to the shield header.
Can change the solder bridge things to pins when I see that it routes okay, same with moving the crystal a scooch and pulling the DB9 off.
Will look at the header spacing also, can move if the db9 is gone.
USB change as well.

Just looking at the extra IO header, the rows aren't .1" spaced.


Rob

Wow, this is like watching a baby being born, only not as wet. :wink:

Lefty

Okay, next pass is ready.

5.5/2.1mm power jack.
Mini USB-B for Serial.
Crystal/capacitors for clock generation.
Full Shield compatibility (standard complement of Arduino pins).
RS232 for Serial1 with 4-pin header (Rx1,Tx1, Gnd, 4th is open). Rx/Tx jumpers to disconnect from driver if need Digital I/O or INT0, INT1.
INT2 available at D6.
Jumpers to select between A4/A5 and SCL/SDA at analog shield header.
Two pins added to analog shield header for A6, A7.
New 8 pin header for PC0-7 (includes SDA/SCL, even if jumpered to A4/A5).
(hmm, looks like I lost an I/O pin for PD7 along the way)
SD MMC push-push with dedicated SPI SS line not available else where on the card. Ladyada style design with Write Protect, Card Detect signals.
Seperate 3.3V regulator for SD card.
FTDI FT232RL USB chip with 3.3V to shield.
ICSP header, allows BIT Bang programmig with FT232RL X3 header.
10 pin JTAG header.
Power LED, "L" (D13) LED, Serial Rx/Tx LEDs (not on Serial1).
No onboard reset - connect externally if needed (at shield pins, at ICSP, or at JTAG)
(tho it appears there is plenty of room to add one, guess one pass to put pads in for it).

My only concern is the USB connector - any one know which library part to use that will let what appear to be the shield pads get connected to ground in Eagle?
Here's close up of what I have now.

The cores at http://www.avr-developers.com will work on Bob's board, as will the bootloader.

They would work on the thing from Atmel as well. The only thing that makes an Arduino an Arduino is the bootloader.

CrossRoads:
Why DIP vs SMD?

Another advantage of DIP is that you could make it available as a kit. If the crystal is in a socket then the user can select the speed they like, although i don't know if a crystal in a socket works as well as a soldered crystal.

Graynomad:
I'd ditch the DB9 and use a header. You can get IDC DB connectors that use ribbon cable so they still look neet and can easily be mounted remotely, makes fitting the board into an enclosure easier and you can swap from male to female without desoldering a connector.

Thats a cool idea!

The cores at http://www.avr-developers.com will work on Bob's board, as will the bootloader.

I agree.

They would work on the thing from Atmel as well.

Nope. millis, micros, delay, and delayMicroseconds will not work correctly at 11.0592 MHz. Which is why I asked if clock speed was the only issue.

RE the RS232 connector.

As soon as you have to solder up wires to headers and connectors it looks like a dog's breakfast. Consider the following

a) serial on a DB9 only needs 3 signals on pins 2, 3 and 5.
b) The smallest IDC connector you can get (AFIAK) is 6-way.
c) You have room for a 2x3 header (same as the ISP header).

So I would add the 2x3 header so there is a quick and neat solution to wiring up serial with IDC connectors.

THEN

If there is room. Add a 2x2 header for jumpers so the polarity can be easily swapped.

All in all this allows two Arduinos to be neatly connected with no crappy soldered wires.


Rob

I'd suggest MicroSD instead of SD - most people have MicroSD cards now and if not then they're not expensive.
Also, due to the size of the DIP chip, you can fit parts underneath it (not that I can see much on your board that could go under it).

So I would add the 2x3 header so there is a quick and neat solution to wiring up serial with IDC connectors.

Could get confusing as 2x3 is the same as the ICSP - I suppose good silkscreening solves this problem.

Looks like my ISP is acting up today, so the files are not viewable. Time for a phone call to see what's going on.

I'll check out RS232 cable headers, see what exists.
Crystals work in sockets, es evidenced by the wirewap boards I have built up.
16/20 MHz - 3-pin socket strip would let one put in either frequency.
There are some parts under the 1284, socket strip intended to be used now to plug in the processor.

SD/MicroSD - maybe I can put both footprints in the same spot so one or the other can be installed.

ISP seems to be back up?
![](http://www.crossroadsfencing.com/Bobuino_rev 1_schematic.jpg)

Ok, looks like the sparkfun microSD footprint will fit nicely under the regular SD footprint. Most signal names to connect in parallel are obvious.

The SD design brings the card detect (CD) and write protect (WP) signals out.

Any ideas if CD1 and CD2 are the same features on the microSD?
And what does RSV do?

If it was my design I would throw out all the auto-voltage switching components and instead use a simple 3 pin SIP and a jumper clip. This would save on component costs and board space avalible for more useful stuff. I never liked the Arduino auto-voltage circuit, looks like a solution looking for a problem.

Lefty

[quote author=Coding Badly link=topic=61126.msg442222#msg442222 date=1305447506]Nope. millis, micros, delay, and delayMicroseconds will not work correctly at 11.0592 MHz. Which is why I asked if clock speed was the only issue.

[/quote]

What happens if the F_CPU is set to that frequency?