Xtag,Xtag2 & JTag

Technical discussions related to any XMOS development kit or reference design. Eg XK-1A, sliceKIT, etc.
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lilltroll
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Re: Xtag,Xtag2 & JTag

Postby lilltroll » Sat Jan 30, 2010 11:21 am

kster59 wrote: If you want USB, ethernet and other peripherals like, I2C/I2S, SPI and SDRAM, it's probably just to program a cheap ARM and hang the XMOS off it with an XLINK. I already made my design with such a configuration and I save a ton of board space and money.
Which ARM chip did you use? there's so many variants of them out there.
Probably not the most confused programmer anymore on the XCORE forum.
kster59
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Postby kster59 » Sun Jan 31, 2010 12:26 am

Check out LPC3130. In qty 1 it's $4.49. They make a $30 LPCXpresso kit for it. Runs linux, wince, etc. Would make a good primary processor for the XMOS.
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lilltroll
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Postby lilltroll » Sun Jan 31, 2010 8:44 pm

OK, maybe out of thread, and someones here will probably dislike this question. But -
When you are doing designs with different types of Hi-Speed ports and you need processing power; compared to this low cost opensource proj:
http://www.hawkboard.org/ what is the tech/cost benefit with XMOS?

That OMAP chip will give you about
2400MIPS+ 1800 MFLOPS
64 General-Purpose Registers
Six ALU (32-/40-Bit), Supports 32-Bit Integer, SP (IEEE Single Precision/32-Bit) and DP (IEEE Double Signals Precision/64-Bit) Floating Point, meaning that you have
Mixed-Precision IEEE Floating Point
2 SP x SP -> SP Per Clock
2 SP x SP -> DP Every Two Clocks
2 SP x DP -> DP Every Three Clocks
2 DP x DP -> DP Every Four Clocks

at about 18$/chip with alot of connectivity including USB2.0, SD-Card, Ethernet, SRAM...

Image

Please remeber, it's a question!
Probably not the most confused programmer anymore on the XCORE forum.
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Folknology
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Postby Folknology » Sun Jan 31, 2010 10:44 pm

I guess the answer might be around latency depending on number of threads required and perhaps power consumption, particularly when there are many raw I/O pins are required. The OMAP silicon you have shown is more like a SoC or PC on a chip and is focused on standard PC peripherals rather than raw I/O. T.I. does have some super chips in its OMAP range but they either have a DSP or PC bias.

If linux style driver development was your target then the OMAP stuff is much more suitable. If you are looking for a more event driven approach then obviously XMOS is the ticket IMHO.
kster59
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Postby kster59 » Mon Feb 01, 2010 2:29 am

For ARM, Keil makes RTX RTOS or you could buy WinCE for around $3/device that does all the event driven stuff and more with more advanced scheduling like priority queues rather than round robin servicing.

However, XMOS has a lot of advantages for special purpose fast I/O. Before your only options were dedicated chips and FPGAs. You can usually get away with a bunch of timers and interrupts but it requires a lot more effort.

Some things are impressive like coding up your own SDRAM driver, ethernet or LCD driver but if I have to dedicate the entire core to it AND substantial effort, it's not economical in money or time. ARM and chips like Intel's N270 Atom have a huge number of libraries for everything where there are well documented libraries that are just better.

That's why I think XMOS with an ARM Xlink would be a good solution for embedded control.

mini-PCI or PCI Express based design would also be very interesting (along with drivers).

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