Hook-up requirements for XUF series chips Topic is solved

Technical discussions around xCORE processors (e.g. General Purpose (L/G), xCORE-USB, xCORE-Analog, xCORE-XA).
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Hook-up requirements for XUF series chips

Postby Gothmag » Sat Dec 17, 2016 6:28 pm

I was looking to make a small board with an XLF series processor with at least 16 cores but it seems digikey doesn't carry them and the MOQ is too high even if I waited. So that prompted me to look at another series and one they do carry is XUF. If I were to use this chip am I required to hook up any of the USB connections to have it work? Specifically it has 2 power, usb_vdd and usb_vdd33. Then the 5 connections for the USB connection itself, usb_dm usb_dp usb_id usb_rtune and usb_vbus.
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Postby mon2 » Sat Dec 17, 2016 10:38 pm


1) USB connections are not required if you are not using the USB PHY (USB function).

2) XMOS can confirm the USB power rails if not used but personally would apply the required voltages for even the disabled USB PHY.

3) Please be aware of the metal belly under this package. Are you ok to consider this package with this metal belly which will need to be soldered ? If yes, you should then be ok to consider BGA devices ?

We sourced our XMOS devices from Future Electronics and with reduced costs. If you are ok with the rom-less version, there is the XE216 in TQFP device (the one we ordered), here:

http://www.futureelectronics.com/en/Tec ... 60539&IM=0

No rom, has USB, has Ethernet. External flash devices are low cost. Future has stock of this part.

Be sure to review power supply current draw, power supply sequencing and their order of power up, how to apply your code into the end product before production of your PCB. Typically this is through the XTAG tool. Another idea is to hold the XMOS CPU in reset and then apply external logic via pogo-pins or similar and then program the target flash device.
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Postby Gothmag » Sun Dec 18, 2016 1:25 am

Thanks for your reply mon2. I was looking for a package with flash for simplicity but it seems like it may not be feasible for this project since the cost goes up so much for so little. I can go either way on the package I just prefer TQFP since they're quicker to R&I if needed. The link you provided looks like it'd work well for now so may just get a few.

The boards will likely have a full xTAG header to start with but using .5mm headers and either an adapter cable, or board(permanently mated to xTAG adapter). Using pogo pins to program flash while holding chip in reset is a good idea, might use that later to remove xTAG. I'll take your advice and at least apply power to the USB power pins as well then just leave the USB function pins NC.

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