I'm looking for a embedded controller for a project. I don't really know what's out there so I don't know where to start looking.

My requirements are:

  • Support for significant amounts of I/O
    • ~150 GPIO (directly or via expanders)
    • Several SPI (or I2C) interfaces
  • Reasonably powerful, able to simultaneously do
    • ~3MIPS
    • ~1MB/s I/O (via SPI/I2C)
    • <1MB/s of eathernet traffic
    • And enough room left over for the parts I'm forgetting
  • Can be used from a standard environment (c, gcc, etc. Not a custom language and IDE)
  • Simple to use (one, maybe two chips, etc.)

My wants are:

  • A "standard" architecture that has many implementations (to minimize the effort if I need to switch chips, for some reason I'm leaning towards ARM)
  • Available on low cost dev boards.
  • Available as chips (mounting a board on a custom PCB seems silly to me)

2 Answers 2


Check out the Digikey website http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=2556109

They have an online configurator where you can spec out your micro piece by piece... there are several that meet your spec. If you load the above page, be sure to scroll to the right, as there are tons and tons of options including package, memory peripherals etc...


I think that one of Atmel middle-class ARM controllers would satisfy almost all of your needs.

For example: AT90SAM7X128 has:

  • 2 SPI (with 4 hardware chip select lines) and 1 I2C interface
  • Ethernet controller
  • DMA channels for all of the peripherals
  • 55Mhz of processing power

Moreover, it is not very costly, and if you want to make some boards by yourself, the LQFP package allows you to do so.

The only drawback is that you need a lot of GPIOs, but AFAIK, it would be cheaper to add a (cheap and stupid) CPLD which only purpose would be GPIO handling. Then you can control it via hardware SPI or just by bit-banging already existing GPIOs.

  • \$\begingroup\$ That chip looks like more than I need, I wonder if that have one with a few less gadgets (not that I couldn't ignore them). --- Re a CPLD, I'd think a more constrained device like a port expander would be cheaper. Something like this: spikenzielabs.com/Catalog/… \$\endgroup\$
    – BCS
    Sep 30, 2010 at 3:00
  • \$\begingroup\$ Why do you think a CPLD is more expensive? mouser.com/ProductDetail/Lattice/LC4032ZE-7MN64C/… \$\endgroup\$ Sep 30, 2010 at 7:24
  • \$\begingroup\$ @TokenMacGuy: I think I saw a 28 I/O chip for about the same or a little less. Even so, not having to muck with yest another programmable device is worth something. \$\endgroup\$
    – BCS
    Sep 30, 2010 at 12:58
  • \$\begingroup\$ @BCS: That's a much better reason than the dollar or two cost. \$\endgroup\$ Oct 1, 2010 at 4:08

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