Working with Mega 2560, need smaller board. Which one?

Using Arduino Project Guidance
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I am working on a project that I have prototyped with the Mega 2560, and everything works as it should. I now need to shrink it down to the size of a 9volt battery.

Which program should I use to do this? I've seen video's of Eagle, but do not know if manufactures prefer eagle. Can it be done, which program should I use, and is there a schematic available or chip even that has the mega's features already incorporated that is shrunken down?

I talked to a manufacture the other day, and they said they recommended that I let them build it from the ground up, not using the mega 2560 schematics. They said the cost would be much cheaper to get the prototype made, but I would still need to program it myself. The problem I have with this is that you have to select which board you are using on the IDE and if I have a custom board, I do not know if I can use the debugging tools that arduino offers that I am accustom to.

It seems arduino is the best board for prototyping, but where do you go from there? I see smaller boards like the nano, and mini, but none of them seem to have the memory and number of pins that the mega has.

Does anyone have any suggestions? If I knew how to use eagle how long would it take to design a multi layered mega2560 that is significantly smaller (of course I wouldn't be able to hand solder anything to it, but at this level I wouldn't want to). Does anyone have contact information of a manufacture that can make the multi level board for me at a reasonable price? What program do you recommend that I use to design the board? What if I get the schematics drawn, can I get the board made for a few hundred? Does anyone know of anyone that can do the schematics if I give them the schematics of everything I am using?

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but do not know if manufactures prefer eagle.

Manufacturers prefer Gerber files, they don't care how they are produced.

if I have a custom board, I do not know if I can use the debugging tools that arduino offers that I am accustom to.

Bootload the part with the Mega2560 bootloader and you can program it as if it was a Mega, using an offboard FTDI Basic module. I made a board that's a small Mega with ICSP header and FTDI header with all pins broken out on 0.1" pitch headers. One of these weekends I'll put one together! Somewhere I've posted pics of the bare PCB.

Smaller header pitch could be used to make it smaller, or a Ball Grid Array package could be used that has a smaller body. Still need to access the 100 pins, so that might need a more expensive 4-layer PCB vs a 2 layer PCB.
I buy PCBs from iteadstudio.com, this size is $9.90 for 10 boards plus shipping. Processors are $17-18, and the crystal/caps/resistor maybe another dollar.

What more do you want the board to do? I do custom design work like this regularly, and have an assembly house I work with for the small pitch parts.

Mega2560_layout.jpg
Mega2560_layout.jpg960×720 158 KB

Mega2560_Sch.jpg
Mega2560_Sch.jpg960×720 67.4 KB

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Are you sure that a smaller processor (Pro Mini board...) won't fit your needs?

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Are you sure that a smaller processor (Pro Mini board...) won't fit your needs?

I haven't looked at the number of pins the pro mini offers, but I can tell you the Pro Mini will not work, It absolutely has to have more Flash(currently using over 150k, and still adding to it), and SRAM than the pro mini offers.

Honestly, I am highly considering adding a SRAM shield to the mega already. As I learn, I continuously find ways to save SRAM, but learning how to takes a lot of time, and lots of code editing. When it runs out, it simply crashes and debugging it is extremely difficult. You can take readings of SRAM at multiple parts, but it constantly changes, and you have to insert the SRAM reading code all over. Strings are so easy to use, if I could have as much SRAM as Flash, it would make my life a whole lot easier, and I would use Strings for everything.

I made a board that's a small Mega with ICSP header and FTDI header with all pins broken out on 0.1" pitch headers. One of these weekends I'll put one together!

You should! The attachments you posted appear to the be mega schematics, and the first appears to be the chip in the middle of the standard Mega. Are the attachments Gerber files?

What more do you want the board to do? I do custom design work like this regularly, and have an assembly house I work with for the small pitch parts.

I can send you the schematics of what I am using that I need in it, but I can tell you the most difficult thing will be the sound module. It must have a way to upload new sound files without removing the sd card. This has been a rather pain in the butt, as with the wi-fi shield you can upload new files without removing the sd card, but I can't seem to find a sound module that has this feature which is a must. I would prefer for it to also be compatible to stream sound using bluetooth.

The WiFi shield part of assembled board must be capable of turning itself off without turning off the arduino because it is to power hungry to leave on full time. To do this, I was thinking about using either a N-channel mosef, a Set-Reset Flip-flop, or a latching I/O relay so that power is supplied to the wi-fi shield only when desired.

Is this something you can do? It will have to be multiple layers to address the space needs. Can you provide any sort of quote?

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The attachments are my design breaking out all pins of a Mega.
The 2560 directly supports adding more SRAM using:

"9. External Memory Interface
With all the features the External Memory Interface provides, it is well suited to operate as an interface to memory devices such as External SRAM and Flash, and peripherals such as LCD-display, A/D, and D/A."

RuggedCircuits.com used to sell a memory shield for that, so it's feasible.

Wifi is usually serial comm's to the uC. You need a shared interface to the SD between the uC and the sound chip (such as VS1003B)?

http://www.mdfly.com/products/vs1003b-audio-decoder.html

PM me, we can discuss more details, such as making this into a multicard system that would stack up somehow to fit into the overall volume you are suggesting. I think the TQFP package size of the 2560 (14mm x 14mm) busts that limit to start, and making room for connecting the boards to each other will also be challenging.
You can see what kind of additional circuitry is needed for the chip and SD socket from some of these cards
http://www.mdfly.com/audio/
and connectors for power, audio out, battery must be added also.

vs1003.pdf (614 KB)

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Adding a MOSFET to power down the Wifi will be one of the simpler things to do.

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CrossRoads:
Adding a MOSFET to power down the Wifi will be one of the simpler things to do.

CrossRoads,
If you can shrink all that functionality down to the volume of a 9v battery I will be impressed :slight_smile:

My latest Mega board is 16x10cm. SDcard, EEPROMS,20x4 LCD,RTCC,RS232,RS485x2,512KB Ram, 64Mb Flash,5x5 keypad,3.3v I2Cx2. (you can see I ran into the Hobbyist Limits) :o

Depending on what he wants, just the Heat load in a 9v battery size would be intense.

The additional SRAM is not hard. You just need the pins. I have a Kickstarter that allows memory access similar to the DOS the EMS standard.

Chuck.

Check out my Kickstarter Project Memory Panes an expansion RAM Shield for Mega2560's. It adds 1MB of RAM for those projects where 8KB is not enough.

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CrossRoads,
If you can shrink all that functionality down to the volume of a 9v battery I will be impressed :slight_smile:

My old room mate gave me his fish tank when he moved out, I think you would find it rather remember-able if you would like to visit sometime.

CrossRoads,
I need to know if you are interested in impressing Chuck. If so, I need to know and i'll see if I can't send you a care package. Which would you prefer?

Care Package A:

  • 180 MHz ARM9 processor
  • 4 MB flash
  • 96 MB of SDRAM
  • FPGA with 500k gates

Care Package B:

  • IBM Power PC 405GPR processor
  • 64 MB SDRAM
  • 16 MB flash
  • 4 mini PCI slots
  • CompactFlash slot
  • 802.11 B/G
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I am interested, as long as you are not in an immediate rush. I always have several paid projects going, and will work yours in.

I have many old PCs laying around, I'm not really interested in collecting more. My main PC now is a Lenovo W530 Workstation wth Intel i7 3840QM processor with 8GB RAM.

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I am interested, as long as you are not in an immediate rush. I always have several paid projects going, and will work yours in.

Excellent! To give me an idea for my projections, would you say 30 days, 90 days, or longer would be a reasonable timeline?