Communication between 3 XC-1As

[tomcarter259]

Hi

I'm working on a project that requires a lot of outputs and I have 3 XC-1A boards to play with.

The input comes into one board via usb, is processed and then either output via the ports on that board or sent to the appropriate board.

I can't use xlinks as I have 3 boards so instead I am planning on sending them using the uart protocol.

Does anybody know a faster way of doing this? Using uart feels a bit like the wrong tool for the job.

Extra info:
The communication would only need to be one-way and the data for each output would be 3 bytes in size

Thanks!

[Folknology]

I can't use xlinks as I have 3 boards so instead I am planning on sending them using the uart protocol.

Hmm there appear to be lots of links available on the XC1A why can't you use links?

Ports and links shown on pages 8 and 9

regards
Al

[Bianco]

I can't use xlinks as I have 3 boards so instead I am planning on sending them using the uart protocol.

Hmm there appear to be lots of links available on the XC1A why can't you use links?

Ports and links shown on pages 8 and 9

regards
Al

The G doesn't support three nodes in a line IIRC.

[Folknology]

OK my bad, I'm used to L series, learnt something new.

How about using SPI

regards
Al

[Heater]

I thought it was possible to support a hypercube topology.

Which implies to me not exactly a line but three nodes connected consecutively in three different dimensions.

If one has to resort to using a UART or other protocol, software driven instead of the link hardware, to connect tree units then there is something totally wrong with the whole architecture.

I can't believe that is true. Can someone expand on this?

[tomcarter259]

As far as I can tell hypercube topology would have to be either 2 or 4 boards.

Page 4 of this guide suggests this:
https://www.xmos.com/download/public/XS ... 1.1%29.pdf

I'll look into SPI, thanks for the suggestion Folknology

[Heater]

Are we really saying that we can't have a 4 chip network as described in the XS1-G Link Performance and Design Guidelines section 6.2 BUT with one of the nodes missing.

I can't believe that.

[Folknology]

6 XS1-G System Topologies
XS1-G multi-chip networks must be connected in a hypercube topology. Three node
XS1-G networks are not supported by the XMOS toolchain.

Thats what it says in the G Link doc, it wasn't something I was aware of either, but that's more down to me working on the L1/2

regards
Al

[dave]

It is possible to connect 3 XC-1As.

The XS1 system specification:

http://www.xmos.com/published/xs1-g-sys ... cification

shows a line of 4 G4s at the top of page 13.

Because of the switch limitations in the XS1, it uses two links between each G4.

If you only want to connect 3 G4s, you can remove (eg) the right hand node (11) in the diagram and one of the links between nodes 01 and 10. This will leave 2 links on node 00, 3 links on node 01 and one link on node 10.

If you use 4-wire links, this should still leave quite a lot of i/o ports.

I had not noticed the statement about the tools and I'm not sure why the limitation exists. I'll find out.

Of course, these switch limitations do not exist on the L series devices.

[Folknology]

Thanks for the clarification Dave

Perhaps we can get the docs updated to reflect this, it dovetails nicely with the githubbing of the docs thread

regards
Al