# Which ARM is best for low power USB device? AT91SAM7S or LPC

**URL:** <https://community.sparkfun.com/t/which-arm-is-best-for-low-power-usb-device-at91sam7s-or-lpc/5922>\
**Category:** MicroMod\
**Tags:** arm-lpc\
**Created:** [December 10, 2007, 5:26pm UTC](https://community.sparkfun.com/t/which-arm-is-best-for-low-power-usb-device-at91sam7s-or-lpc/5922 "2007-12-10T17:26:27Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![mpanetta](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@mpanetta](https://community.sparkfun.com/u/mpanetta)\
**Post date:** [December 10, 2007, 5:26pm UTC](https://community.sparkfun.com/t/which-arm-is-best-for-low-power-usb-device-at91sam7s-or-lpc/5922/1 "2007-12-10T17:26:27Z")

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I am working on a small project that will be connected to USB so I need a controller with a USB device interface on it. Question is, which one? The main criteria are cost (isn’t it always?) and power consumption. I also want something thats easy to use, and has a ready to use USB stack that will allow me to do 3 virtual com ports. (2 are real hardware UARTS the third will be a command interface).

So far I have looked at the Atmel AT91SAM7S chips and the LPC23xx chips. The SAM chips have a USB stack that I could download now and see if it will do what I want, does the LPC chip have that? I can’t seem to find one. Also, the SAM chips actually seem cheaper, as the SAM7S64 is about $4 in quantity and the SAM7S128 is about $6, but the 64K LPC part is about $6 or more (all from digikey). Does this sound right?

All I really need as far as peripherals go are one or 2 UARTS and an I2C interface, Other then that I am pretty flexible.

Any ideas? Does anyone here have experience on getting USB up and running on one of these chips?

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**Author:** ![leon\_heller](https://yyz1.discourse-cdn.com/sparkfun/user_avatar/community.sparkfun.com/leon_heller/32/7602_2.png) [@leon\_heller](https://community.sparkfun.com/u/leon_heller)\
**Post date:** [December 10, 2007, 6:13pm UTC](https://community.sparkfun.com/t/which-arm-is-best-for-low-power-usb-device-at91sam7s-or-lpc/5922/2 "2007-12-10T18:13:20Z")

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We have some USB code in the LPC2000 Yahoo group files section.

Leon

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**Author:** ![dshuman](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@dshuman](https://community.sparkfun.com/u/dshuman)\
**Post date:** [December 10, 2007, 8:36pm UTC](https://community.sparkfun.com/t/which-arm-is-best-for-low-power-usb-device-at91sam7s-or-lpc/5922/3 "2007-12-10T20:36:25Z")

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> mpanetta:  
> All I really need as far as peripherals go are one or 2 UARTS and an I2C interface, Other then that I am pretty flexible.
> 
> Any ideas? Does anyone here have experience on getting USB up and running on one of these chips?

You can find a complete package for a lot of the LPC peripherals here:

[www.jcwren.com/arm](http://www.jcwren.com/arm)

It is targeted for the LPC2148, but it includes a USB implementation among a lot of other useful code for LPC chips.

–Dave

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<div class="post-metadata">

**Author:** ![mpanetta](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@mpanetta](https://community.sparkfun.com/u/mpanetta)\
**Post date:** [December 10, 2007, 8:53pm UTC](https://community.sparkfun.com/t/which-arm-is-best-for-low-power-usb-device-at91sam7s-or-lpc/5922/4 "2007-12-10T20:53:16Z")

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LPCUSB looks _very_ promising! The LPC2364 is only ~$5 in 100’s at digikey and looks to fit perfectly, all though the package is a bit large, but I can deal with that (or switch to BGA…)

I may just have to whip me up a board for this chip…

Thanks,

Mike