My 1st XMega Project

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My 1st XMega Project

· Posted: 31.10.2011 - 08:13 · #1

HI All,

I'm starting a new project with LCD, SPI, TWI, Ethernet, MMC etc and thought I would give a XMega IC a try.
So which device to pick?
With the above hardware in mind, I'm looking at the following XMega spec :
- >64MB Flash
- >8KB SRAM. I see some go to 32KB
- >= 2 SPI ports (Ethernet & MMC etc) more SPI's would be nice.

Looking on ATMEL site, I have a choice of -
- ATxmega192A3U
- ATxmega256A3U
- ATxmega256A3BU (Also has battery backed RTC capability)

Some questions
1. How pin compatible are these devices ie I make a board to suit the xmega192, can I later drop in the xmega256 or xmega384 device?

2. With my plan to allow for the Battery backed RTC, I will of course, need to design the board with this in mind but other than that, are they the same pin out?

3. For the above ic's, they appear to be a MLF (VQFN) 64,TQFP 64. Which is preferable?

4. What AVRCo programmer interface to use? (I have a ISP3-USB, Firmware 111021)

5. What to use as the master oscillator? External crystal or the internal oscillator?

6. What about the ATxmega384 what package does it come in?

Thanks,
Neil.

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Re: My 1st XMega Project

· Posted: 31.10.2011 - 11:32 · #2

Hello Neil,

1. all x1x devices come with 100pins, all x3x with 64pins, all x4x with 44pins
2. B devices have a special RTC, but there are some IO-parts missing, not compatible
3. TQFP is available, QFN sometimes not. Devices with the same pin count are always compatible
4. your ISP3 supports XMega programming
5. the internal OSC are very precise, sufficient for UARTS and also for USB, no XTAL needed

Don't use XMegas without USB. The USB devices are heavily shrinked compared to the
mature ones, for example 128A1. They run (out of specs) upto 64MHz. At this time
I know that XMega256A3U is available as samples. I have some. You must ask a very
qualified Atmel distributor for samples. Digikey and Mouser don't know these devices
at this time.

rolf

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Re: My 1st XMega Project

· Posted: 31.10.2011 - 11:40 · #3

Thanks Rolf,

What programming interface should I put on the board? PDI or JTAG?

So no crystal?

What do you mean my heavily shrinked?

Neil.

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Re: My 1st XMega Project

· Posted: 31.10.2011 - 12:00 · #4

Hello Neil,

only PDI is supported because the 44pin XMega have only PDI. And JTAG is only a wrapper around the PDI, complex, difficult and wasting pins.
You absolutely don't need an XTAL. The internal RC-OSC are very precise and sufficient for any application. Except you need nsec-precise timers.
Shrinked means the internal CMOS structures now are much smaller than the mature ones. The effort for this is smaller chip size, lower cost, less current consumption and last but not least higher speed.

btw. In the AVRfreaks forum there is a user "Alexandra" who is an employee of an australian
Atmel distributor. He/she claims that they have "U" samples.

rolf

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Re: My 1st XMega Project

· Posted: 31.10.2011 - 21:18 · #5

Thanks Rolf,
Neil.

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Subject:

Re: My 1st XMega Project

· Posted: 01.11.2011 - 11:10 · #6

XMEGA USB family seam to have ADC problem solved:
http://www.avrfreaks.net/index…c&t=109436

My 1st XMega Project

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