USB-SPI Examples and Specs ?

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Who-me
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Posted by Who-me: Sat. Jun 9, 2012 - 06:48 AM
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Since it looks like the new USB XMega's are just about mission ready, we are looking for examples of USB-SPI and sustainable speed numbers ?

The task is broadly similar to a large device programmer, but with more balanced Tx/Rx loads.

We need > ~2MBd, each way, which pushes UART solutions,

Xmega looks like a good fit, if we can find the SW side. Price seems to have come down, and bugs seem to be fixed since I last looked.

Other candidates are
* FT232H : should meet speed, but moderately expensive.
* FT-X series - less sure about speed, but better price and very small packages, but we still need a uC
* PSoC3 : expensive, no small packages.
* VNC2 : Moderate price, good code size, has small packages, but lacks ADC.
* PIC18 : Versions with enough RAM climb in price
* PIC32 : Might also fit, does have good RAM.Code choices, in smaller packages, but this app does not really need a 32 bit CPU.

I've seen comments suggesting LUFA is almost XMega ready - but the website seems further back than posts here suggest ?

What other USB-SPI Xmega SW alternatives are there, and what Xmega HW PCB platforms are a good development base for USB-SPI work on the XMega ?

Tags:

AVR Microcontrollers, AVR and XMEGA
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abcminiuser
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Posted by abcminiuser: Sat. Jun 9, 2012 - 09:42 AM
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Quote:

I've seen comments suggesting LUFA is almost XMega ready - but the website seems further back than posts here suggest ?

Having just had the most unpleasant encounter with someone who assumed that contrary to the documentation and who is now trying their damnedest to make me into a scapegoat, I'll warn here pre-emptively: it's not ready yet.

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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Who-me
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Posted by Who-me: Sat. Jun 9, 2012 - 11:10 AM
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Thanks for the update - but it is close ?

When you are testing it, I'd be interested in the loop-back speeds, running something like a SPI loop (or USART in SPI mode ) and what is the optimum packet size range.

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abcminiuser
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Posted by abcminiuser: Sat. Jun 9, 2012 - 12:36 PM
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Quote:

Thanks for the update - but it is close ?

The latest trunk (not release!) works for at least HID, Mass Storage and Virtual Serial, but with some caveats. The code is not ready for production use and the demos are not multi-arch aware yet, but you can find some sample demos on the LUFA support list.

You're welcome to help test it, but keep in mind that a gigantic pile of caveats and warnings apply as I'm still in the development phase.

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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DocJC
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Posted by DocJC: Mon. Jun 11, 2012 - 12:34 AM
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Quote:
what Xmega HW PCB platforms are a good development base for USB-SPI work on the XMega ?

For Xmega development boards have a look here .

JC

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Who-me
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Posted by Who-me: Mon. Jun 11, 2012 - 01:36 AM
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DocJC wrote:

For Xmega development boards have a look here .

JC

Thanks, I had found that but most seem to have not quite caught up with the USB models...

It looks like the Xmega-A3BU Xplained, is probably going to be the best ? (and likely to be high on Dean's test list too.. ;) )

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DocJC
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Posted by DocJC: Mon. Jun 11, 2012 - 02:37 AM
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I beleive that Gabriel's Xprotolab is now shipping with the Xmega32A4U, which gives you at least an option from which to select which one best meets your needs.

JC

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