Minimal reference board layout for XS1-L6A-64-TQ128

[SpacedCowboy]

Hi all,

So I'm in the initial stages of designing a circuit which needs 2 8-bit FIFO's, and reasonably-fast FIFO chips are expensive ($20 each), so I thought I'd try rolling my own with an XS1 ($8 at digikey, quantity-1). In the TQ128 package there are 4 8-bit ports available, as well as sufficient 1-bit ports to handle {data,space} available and corresponding {read, write} pins.

So, to do this I want as minimal a layout as possible - just enough to program the device, store the program on serial flash so it can be useful without the programmer attached, and the pins for the FIFO requirements.

It's been a while since I used xmos parts, but I recall there were specific power-on requirements, and I was looking for a schematic that implemented those requirements to use as a cheat-sheet. There is one in the XK-1A-Hardware-Manual.pdf which looks pretty straightforward and I guess my question is would that schematic apply to the newer part XS1-L6A-64-TQ128 ? I'm hoping so, but thought it would be good to ask...

Cheers
Simon

[Andy]

Hi all,

So I'm in the initial stages of designing a circuit which needs 2 8-bit FIFO's, and reasonably-fast FIFO chips are expensive ($20 each), so I thought I'd try rolling my own with an XS1 ($8 at digikey, quantity-1). In the TQ128 package there are 4 8-bit ports available, as well as sufficient 1-bit ports to handle {data,space} available and corresponding {read, write} pins.

So, to do this I want as minimal a layout as possible - just enough to program the device, store the program on serial flash so it can be useful without the programmer attached, and the pins for the FIFO requirements.

It's been a while since I used xmos parts, but I recall there were specific power-on requirements, and I was looking for a schematic that implemented those requirements to use as a cheat-sheet. There is one in the XK-1A-Hardware-Manual.pdf which looks pretty straightforward and I guess my question is would that schematic apply to the newer part XS1-L6A-64-TQ128 ? I'm hoping so, but thought it would be good to ask...

Cheers
Simon

Hi Simon,

Yes, the L4, L6 and L8 parts are identical in pinout and design requirements to the L1 equivalents.

Beware - don't copy the flash pinout from the XK-1A as it uses a custom bootloader to boot from non-standard flash pins. Take a look at the XTAG-2 schematics for a very simple example of power supply and sequencing (although it doesn't have a flash): http://www.xmos.com/support/downloads?c ... nent=16824

You should be able to avoid using a flash at all if you keep your program under around 6KB by burning it into the OTP.