The official XS1-SU1 discussion thread

Technical discussions around xCORE processors (e.g. xcore-200 & xcore.ai).
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shawn
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Post by shawn »

leon_heller wrote:What is the intended application for the on-chip ADC? Being only 12-bits, it isn't suitable for high-quality audio, which is obviously where the device will mainly be used.
I don't know about that? there is a lot of oversampling and who knows with proper conditioning and a small array
of XS-1SU1's with their ADC's multiplexed you could achieve a higher ENOB's, plus trix, like RIS random insertion sampling or sampling modulated oscilators for FM synthisis. The thing about developers is, they will find unique ways to utilized there tools, like musicians :mrgreen:


bearcat
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Post by bearcat »

Couple quick questions.

1 - Is the audio-dj design to be released soon?
2 - Possible to use a little power from the 1.8V internal regulator (10mA max) to drive another chip? The specs of the USB SMC part list a max of 34mA on 1.8V, if that is what got integrated, and is far less than the 1.0V consumption from probably a similiar regulator.
3 - Can I assume the low input impedance errata on JTAG etc is fixed?
4 - MODE_BOOT Pin not detailed? I might assume low for external clock, high for internal clock?
5 - TEST signals should be ignored in a design and left open and not traced out?
6 - ADC voltage range. Listed as ADC_VREF max, 0 min. On many microcontrollers, usually protect inputs with diodes to supply and ground with a resistance, and preferably a silicon diode. The specs don't seem to indiciate this? If not, how to protect the inputs?
7 - VINQ Pin? What is this?
8 - WAKE Pin. Tie low if not used?

Edited. Added 7 and 8.
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JohnWilson
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Post by JohnWilson »

bearcat wrote:7 - VINQ Pin? What is this?
In the "signal description" table (only!) it's labeled as "PMU voltage (PVIN1/PVIN2)", which *sounds* like it means it wants to be tied to the +3.3/+5 supply for whatever reason. Or maybe not. Who knows! It'd be nice to know about that (and WAKE) in time to have prototype PCBs made by the time samples are available.
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JohnWilson
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Post by JohnWilson »

Apparently the Rev B data sheet came out on Tuesday, but all it does to clarify these two pins is change the description of VINQ to "Input power voltage". Still no idea what that does, or how to use (or not use) the WAKE pin. Someone from XMOS please enlighten us!

John Wilson
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JohnWilson
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Post by JohnWilson »

Thank you Joe at XMOS! He answered my support ticket and apparently the deal with these pins is: WAKE should be left unconnected if not used, and VINQ should get a 0.1 uF bypass cap and should connect to the same source as the two PVIN pins (which are connected together and get one 4.7 uF cap and one 0.1 uF cap for the pair of pins -- part 16 of the Rev B data sheet says two of each but I guess not). Time for a prototype PCB!!!

John Wilson
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rp181
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Post by rp181 »

When is this supposed to be available for purchase? I would like to use it as the master on a 4x L1 pipeline.
narutoxela
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Post by narutoxela »

The chip is supposed to be available in Q2 but aren't we allready in Q3?
dirk1980
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Post by dirk1980 »

Hi,

i have to build a new USB Audio System and i will use the new XS1-SU1.
Can i buy them today or just somewhere in the future?

I need them today, because i need the hole system in a Product next Week.
If not, i have a problem, because the hole Power an Reset system of a L1 or L2 Xmos is to expensive.

Dirk
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Bianco
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Post by Bianco »

dirk1980 wrote:Hi,

i have to build a new USB Audio System and i will use the new XS1-SU1.
Can i buy them today or just somewhere in the future?

I need them today, because i need the hole system in a Product next Week.
If not, i have a problem, because the hole Power an Reset system of a L1 or L2 Xmos is to expensive.

Dirk
Contact XMOS asap to see if you can get samples.
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ahenshaw
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Post by ahenshaw »

What value of resistor should I use between the USB connector and the USB_VBUS pin? I'm assuming 100K, based upon some other device designs that I've seen, but I'd like to confirm that.
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