I2C on Port 32A7 and 32A8

Technical questions regarding the xTIMEcomposer, xSOFTip Explorer and Programming with XMOS.
User avatar
Ross
XCore Expert
Posts: 748
Joined: Thu Dec 10, 2009 9:20 pm

Re: I2C on Port 32A7 and 32A8

Postby Ross » Tue May 01, 2012 10:56 am

I do not believe this restriction was stated. If sharing SDA and SCL on a single port is the only requirement (and a restricted I2C implementation is satisfactory) then the single port module should be fine.

For a full I2C compliant solution you need to use two separate ports (1-bit or otherwise).

Many devices do not support clock-stretching, you may even get around this with increased time-outs etc.
User avatar
segher
XCore Expert
Posts: 843
Joined: Sun Jul 11, 2010 1:31 am
Contact:

Postby segher » Tue May 01, 2012 12:01 pm

Not stated no, but I think it is a reasonable assumption that if he has I2C on
pins 7 and 8 of a 32-bit port, he has other stuff on the other pins on that port :-)
User avatar
GeorgeIoak
Active Member
Posts: 45
Joined: Wed May 19, 2010 9:42 pm

Postby GeorgeIoak » Tue May 01, 2012 6:11 pm

To make it 100% clear, yes there are other connections on the 32-bit port. Now Ross makes me think that perhaps this is possible so I'm hoping for some further clarification.

Looking at some of the reference designs I see that the USB Audio shares the 32-bit port with other connections, specifically, 1/2 of the ULPI bus is on the P32A. Since that obviously has to switch between input and output while not impacting the other connections how is that handled?
User avatar
Ross
XCore Expert
Posts: 748
Joined: Thu Dec 10, 2009 9:20 pm

Postby Ross » Wed May 02, 2012 6:51 pm

Do you mean the L1 USB Audio Reference Design? If so all the signals used on the 32bit port are outputs I'm afraid (CODEC reset, USB phy reset, LEDs etc)
User avatar
GeorgeIoak
Active Member
Posts: 45
Joined: Wed May 19, 2010 9:42 pm

Postby GeorgeIoak » Wed May 02, 2012 8:39 pm

Yes, I did mean the L1 USB Audio Reference Design. Looking at the connections I thought at first that the following ULPI data signals were connected to the 32-bit port.

ULPI_DATA0 -- P32A28
ULPI_DATA1 -- P32A29
ULPI_DATA6 -- P32A30
ULPI_DATA7 -- P32A31

But I see now that P8B takes precidence and that is the port the ULPI are "really" connected to.
User avatar
Ross
XCore Expert
Posts: 748
Joined: Thu Dec 10, 2009 9:20 pm

Postby Ross » Thu May 03, 2012 10:42 am

Oh i see. Yes, "Smaller" ports take presidence.

Return to “Development Tools and Programming”

Who is online

Users browsing this forum: No registered users and 7 guests