New board - '1284 Mini

I’ve had a few inquries about a '1284 in small form factor, so I put a TQFP part on a small board with the components needed to run standalone and added independent headers for ICSP and FTDI for bootloading & sketch downloading. Even put a couple of LEDs on since the headers sort of forced the overall size. Added a bunch of ground connections too.
I’ll put an order in for boards in a few days.
Parts are standard - 16 MHz xtal, 0805 size caps & resistors, 0.1" pitch headers, 1206 LEDs, and a DO214BA size diode for non-lockup sketch downloads.
Offboard 4.5-5V power needed. 3V for 8 MHz.

Pinout is the Mighty1284/Bobuino variant.

Add your favorite '324/644/1284 into your project and take advantage of 32 IO lines.

Pick up a metal stencil for $11
http://www.proto-advantage.com/store/product_info.php?products_id=2220108
and away you go for easy assembly!
Board is 48.25 x 44.5mm, 1.9" x 1.75", I’ll be ordering in lots of 10.
1-piece shipped to you for $3.00, price will drop with higher quanties as I can mail several for the same postage cost.
Will pester all requestors for paypal funds after I get the boards in ~July 20 if ordered this weekend.

I’m open to suggestions for improvements too. If the board is allowed to grow to 50mm x 50mm, a few more components could be added.

Robert

Looks good.


Rob

Yeah, there's really not much needed for a standalone board that is intended to be used independend of a PC.

I like the board, it looks very good! I might be greedy but, could you add a RX , TX led to D0 and D1?

I would like 2 boards either way, but, for me seeing the serial at work is helpful.

Always good work!, Mark

Looks interesting, I be in for one or two. I would be even more interested if you made the boards an even 2" square. If they were 2" on a side they would be very compatible with the Schmartboard prototyping boards which I think work very well for prototype circuits, particularly those that use SMD components.

wanderson: Looks interesting, I be in for one or two. I would be even more interested if you made the boards an even 2" square. If they were 2" on a side they would be very compatible with the Schmartboard prototyping boards which I think work very well for prototype circuits, particularly those that use SMD components.

Do you have some idea for stacking boards?

Adding spots for LEDs/resistors would be doable.

2" is a tad too big - I want to keep it 50mm x 50mm max (1.96"), otherwise it bumps up into the next price bracket.

If I make it 50x50 and move the pins out to the edge, with names inside the headers, that would make a nice footprint for shields. I’ll double check to make sure the pins line up for a perboard when I move them.
Can bring the power in from the top shield, or use right angle headers at the +5/GND pins. I’ll beef up those traces so power can come in any +5 pin and go out any +5 pin up to shields. Maybe do a ring with +5 around the outside of the board.

cyclegadget:

wanderson:
Looks interesting, I be in for one or two. I would be even more interested if you made the boards an even 2" square. If they were 2" on a side they would be very compatible with the Schmartboard prototyping boards which I think work very well for prototype circuits, particularly those that use SMD components.

Do you have some idea for stacking boards?

No I connect the boards along the sides using plastic clips Schmartboard manufactures. By themselves they are fairly secure; however, I add a little super glue to make them as solid as a single board.

CrossRoads:
Adding spots for LEDs/resistors would be doable.

2" is a tad too big - I want to keep it 50mm x 50mm max (1.96"), otherwise it bumps up into the next price bracket.

If I make it 50x50 and move the pins out to the edge, with names inside the headers, that would make a nice footprint for shields. I’ll double check to make sure the pins line up for a perboard when I move them.
Can bring the power in from the top shield, or use right angle headers at the +5/GND pins. I’ll beef up those traces so power can come in any +5 pin and go out any +5 pin up to shields. Maybe do a ring with +5 around the outside of the board.

50mm (1.96") is likely the size of the Schmartboards, since it is a nice even metric measurement. I would be in for 10 if you make them that size. Just let me know when your ready to order.

I'll do a little more work & re-post, adding some securing holes along the edges too. I'm not in a rush, discussing these little mods only helps add to the utility of the design.

Since it is mostly SMD, why not choose an SMD push button, like this one: http://iteadstudio.com/store/index.php?main_page=product_info&cPath=10_15&products_id=334 (And honestly, I have never used the reset button on any board.)

I have a well stocked box of 0603 components... never bought 0805 caps, just some small-value resistors and LEDs. Would 0805 pads fit an 0603 cap (e.g. for the 22pF xtal load caps?)

Yes, 0603's will fit on 0805 pads.

I don't normally install a reset switch at all, was a moment of weakness I think. I changed it over.

Okay, here’s a 1.95" board, LEDs on D0/D1, SMD reset switch, 4 layed in the possible configuration showing alignment match up.
All the header holes are on 0.1" pitch.
Wondering if I should drop to 1.9 x 1.9 so the holes don’t look 0.05" off when side by side.
Thoughts?

Hi, I really like the look of this board, is it compatable with the Arduino interface/IDE ?

I would consider taking a couple at least.

Will you have the total bill of materials posted? I am not so good at looking the parts up on my own yet.

Thanks sir.

Yes, is fully Arduino code compatible. Download manaicbug’s Mighty1284 core files, and select Bobuino as board type.

Download bootloader via the ICSP header, download sketches via the FTDI header.

Here’s a mouser.com parts list. Not much there:
(you can see my thoughts on things I need to check still)
I’ll post a schematic shortly & make sure I got it all, and the pads sizes all agree.

1x Atmega1284P-AU, 556-ATMEGA1284P-AU
1x 16 MHz xtal/H49S, 815-ABL-16-B2
1x 10K 0805/1220 size resistors, 1/10W, 754-RR1220P-103D
6x 0805/2012 size 100nF capacitors, 80-C0805C104K4R
2x 0805/2012 size 22 pf capacitors, 80-C0805C220J5G
1x size 0805/2012 10uF capacitor, 603-CC805KKX5R6BB106

1x size 1206 chip LED, green, 2.6V, 720-LGN971-KN-1 >> 240 ohm for 10mA
1x 1K 0805/1220 size resistors for LEDs, 1/10W, 754-RR1220P-241D

1x size 1206 chip LED, yellow, 2.6V, 720-LYN971-HL-1 >> 240 ohm for 10mA
1x 1K 0805/1220 size resistors for LEDs, 1/10W, 754-RR1220P-241D

1x size 1206 chip LED, red, 1.8V, 720-LHN974-KN-1 >> 160 ohm for 20mA (lower mcD)
1x 1K 0805/1220 size resistors for LEDs, 1/10W, 754-RR1220P-161D

1x size SOD123 diode,771-BAT54H-T/R <<< confirm size of pads on board, need 1.7mm x 3.6mm max

1x size 4.5mm reset switch, 612-TL3315NF250Q <<< check size of pads on board, need 4.6mm x 5.15mm

0.1" pitch headers as your project requires - single row, double row, straight, right angle, male/female, etc.
1x6 0.1" pitch male pins for FTDI header
2x3 0.1" pitch male pins for ICSP header

Hmm, single row header - there are no grounds on the inner row. I’ll add some so you’re not forced to add double row headers if you don’t need that. There is room now with the headers being pushed out into a more square shape.

754-RR1220P-161D 754-RR1220P-241D

Are backordered.

754-RR1220P-181D >> 180 ohm, was 160
754-RR1220P-221D >> 220 ohm, was 240

I decided to go with 1.9" square, looks much better aligned when boards are next to each other, will make for cleaner groups of assemblies I think going forward.
All parts above confirmed (adjusted 2-3 pads on the board).
Added extra ground pads at the end of the inner rows to allow for singler-row headers if desired.

Will order cards tomorrow afternoon if there’s no further suggestions.
Any suggestions for mating boards?

And the updated schematic. Might have left an LED/resistor off the PL above.