Replies: 9
Views: 205
Last Post By: yzoer ON: Thu May 17, 2012 10:37 pm
Topic By: yzoer ON: Thu May 17, 2012 10:37 pm
Thanks for the tip but I already confirmed it's the board, as the same test on another board worked as it should :-)

-Yvo

Replies: 1
Views: 19
Last Post By: segher ON: Thu May 17, 2012 10:29 pm
Topic By: segher ON: Thu May 17, 2012 10:29 pm
It looks like you specified the wrong XN file, or your XN file is wrong.

Replies: 1
Views: 19
Last Post By: segher ON: Thu May 17, 2012 10:29 pm
Topic By: Alexb ON: Thu May 17, 2012 8:26 pm
How can I flash my programme on a dual Xk-1a?

this is the error I get when I try :

Replies: 9
Views: 205
Last Post By: yzoer ON: Thu May 17, 2012 10:37 pm
Topic By: sethu ON: Thu May 17, 2012 3:06 pm
I know this might sound silly to you, but can you try to assign the ports directly instead of using them in XN file and see if it works.

Say, Instead of using this,
out port led = PORT_BUTTON_LED_0;
in port button = PORT_BUTTON_A;
use
out port led = XS1_PORT_ 1E;
in port button = XS1_PORT_4C;

Replies: 35
Views: 918
Last Post By: lilltroll ON: Thu May 17, 2012 11:49 am
Topic By: lilltroll ON: Thu May 17, 2012 11:49 am
Hmm, it should be easy to compute the filter-response for the lo-part, and add it to the accumulator for the next sample.

Replies: 35
Views: 918
Last Post By: lilltroll ON: Thu May 17, 2012 11:49 am
Topic By: asibbald ON: Thu May 17, 2012 10:34 am
Sorry - spot the deliberate mistake. Dattorro's paper was 1988 not 1982

Replies: 35
Views: 918
Last Post By: lilltroll ON: Thu May 17, 2012 11:49 am
Topic By: asibbald ON: Thu May 17, 2012 10:03 am
Guys,
This discussion is very interesting and a lot of good work is being done on high quality Biquads here.
However, there is an additional approach that is worth taking into account. The definitive work on this alternative/additional approach was done in 1982 by Jon Dattorro:


J. Dattorro, “The Implementation of Recursive Digital Filters for High Fidelity Audio,” J. Audio Eng. Soc., vol 36, pp 851-878 (1988 Nov)

A very useful summary of the situation was presented by Marc Allie at the comp.dsp conference in 2004. His presentation is available here:

www.danvillesignal.com/files/compdsp_Al ... Filter.ppt

In essence, Dattorro presents a computationally efficient means of "error correcting" the roundoffs and obtaining a SNR equivalent to that that would be obtained by a "Brute force" method using a far higher number of bits.

Whilst Dattorros paper - being 1982 - deals with 16-bit computation, the algorithm he presents is general and can in principle be applied to any number of bits.

Well worth reading. I'd suggest the Allie presentation first as a good overview.

Replies: 2
Views: 70
Last Post By: lilltroll ON: Thu May 17, 2012 5:51 am
Topic By: lilltroll ON: Thu May 17, 2012 5:51 am
The ideá is not not loose any data with samples.

If you need a longer buffer, there is code-package for that from XMOS.
You may also use a select() on the RX side. This way you can read in the channeldata when it exists, and choose if you want to discard it on the RX side instead, not stalling the TX side.

Replies: 2
Views: 70
Last Post By: lilltroll ON: Thu May 17, 2012 5:51 am
Topic By: segher ON: Thu May 17, 2012 2:44 am
The proper way to avoid t0 blocking is of course to not send more
data than t1 can swallow up; so let's assume this is for recovering
from some bad situation, data loss is unavoidable.

When a thread is blocked on some I/O instruction, event or interrupt
requests will still be honoured. I don't think you can set things up
in XC for this, so you'll need some little asm or C code. Your idea
of using a timer is probably the easiest way to go.

Replies: 34
Views: 2125
Last Post By: JohnWilson ON: Thu May 17, 2012 1:52 am
Topic By: JohnWilson ON: Thu May 17, 2012 1:52 am
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
D Bit