I2C on Port 32A7 and 32A8

Technical questions regarding the XTC tools and programming with XMOS.
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Ross
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Post by Ross »

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.


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segher
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Post by segher »

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 :-)
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GeorgeIoak
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Post by GeorgeIoak »

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?
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Ross
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Post by Ross »

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)
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GeorgeIoak
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Post by GeorgeIoak »

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.
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Ross
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Post by Ross »

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