Re: [beagleboard] SPI and I2C port use?

2015-09-03 Thread William Hermans 
>
> *SPI has a dedicated CS line. You can and that with a GPIO pin and create
> more CS signals if you like.*


Wonder why more people do not realize this ? SPI on Linux is software . .
.a CS "line" pin, etc is just a toggled GPIO high/low at the appropriate
times. . . .

On Thu, Sep 3, 2015 at 5:41 AM, Gerald Coley  wrote:

> EEPROM is in I2C0 which does not connect to the expansion headers. I2C2 is
> a shared bus. As long as no tow devices have the same address, you are
> limited to 255 different devices on an I2C bus.
>
> SPI has a dedicated CS line. You can and that with a GPIO pin and create
> more CS signals if you like.
>
> CODECS typically uses I2S which is a totally different animal. But there
> are SPI and I2C CODECs out there.
>
> Gerald
>
> On Thu, Sep 3, 2015 at 6:34 AM, Rick Mann  wrote:
>
>> I'm having trouble figuring out which SPI ports are available on the BBB
>> if I want to continue to use the eMMC.
>>
>> I also need to connect I2C and SPI to an audio codec IC. I think I can
>> use any I2C/SPI port combination, right? Just might have to modify the
>> driver a bit? I'm using the same codec as on the BBB Audio Cape.
>>
>> But I was hoping there'd be an additional SPI port I could use for
>> something else on my cape, and still be able to use the eMMC.
>>
>> Lastly, the EEPROM is on I2C2, right? Can I share that with the audio
>> codec? That would let me wire it the same as the Audio Cape, might make it
>> easier to get the software working.
>>
>> Thanks,
>>
>> --
>> Rick Mann
>> rm...@latencyzero.com
>>
>>
>> --
>> For more options, visit http://beagleboard.org/discuss
>> ---
>> You received this message because you are subscribed to the Google Groups
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>>
>
>
>
> --
> Gerald
>
> ger...@beagleboard.org
> http://beagleboard.org/
>
> --
> For more options, visit http://beagleboard.org/discuss
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Re: [beagleboard] SPI and I2C port use?

2015-09-03 Thread Rick Mann 

> On Sep 3, 2015, at 05:41 , Gerald Coley  wrote:
> 
> EEPROM is in I2C0 which does not connect to the expansion headers. I2C2 is a 
> shared bus. As long as no tow devices have the same address, you are limited 
> to 255 different devices on an I2C bus.

Sorry, I meant the cape EEPROM, not the BBB's EEPROM.

> SPI has a dedicated CS line. You can and that with a GPIO pin and create more 
> CS signals if you like.

The WiFi cape has some incompatibility with the eMMC, is it just because it's 
trying to use the same CS line?

> CODECS typically uses I2S which is a totally different animal. But there are 
> SPI and I2C CODECs out there.

The CODEC I'm using is the same one on the Audio Cape 
(http://elinux.org/images/1/11/Audio_Cape_B1_Schematic.pdf), a tlv320aic3104 
(http://www.ti.com/lit/ds/symlink/tlv320aic3104.pdf). It is I2S, and uses an 
I2C and SPI bus (at least, that's how the Audio Cape is connected).

Hmm, looking more closely, it's using the SPI1 pins, and a GPIO, but doesn't 
seem to be actually using the SPI bus. That's confusing. Oh, looking at the DTS 
(http://elinux.org/images/1/10/BB-BONE-AUDI-02-00A0.zip), it seems to be using 
McASP in I2S mode?

I don't know if it's possible to use McASP on different pins...


> 
> Gerald
> 
> On Thu, Sep 3, 2015 at 6:34 AM, Rick Mann  wrote:
> I'm having trouble figuring out which SPI ports are available on the BBB if I 
> want to continue to use the eMMC.
> 
> I also need to connect I2C and SPI to an audio codec IC. I think I can use 
> any I2C/SPI port combination, right? Just might have to modify the driver a 
> bit? I'm using the same codec as on the BBB Audio Cape.
> 
> But I was hoping there'd be an additional SPI port I could use for something 
> else on my cape, and still be able to use the eMMC.
> 
> Lastly, the EEPROM is on I2C2, right? Can I share that with the audio codec? 
> That would let me wire it the same as the Audio Cape, might make it easier to 
> get the software working.
> 
> Thanks,
> 
> --
> Rick Mann
> rm...@latencyzero.com
> 
> 
> --
> For more options, visit http://beagleboard.org/discuss
> ---
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> 
> 
> 
> -- 
> Gerald
>  
> ger...@beagleboard.org
> http://beagleboard.org/
> 
> -- 
> For more options, visit http://beagleboard.org/discuss
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-- 
Rick Mann
rm...@latencyzero.com


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Re: [beagleboard] SPI and I2C port use?

2015-09-03 Thread Rick Mann 

> On Sep 3, 2015, at 11:30 , William Hermans  wrote:
> 
> SPI has a dedicated CS line. You can and that with a GPIO pin and create more 
> CS signals if you like.
> 
> Wonder why more people do not realize this ? SPI on Linux is software . . .a 
> CS "line" pin, etc is just a toggled GPIO high/low at the appropriate times. 
> . . . 

I'm actually well aware of how SPI works. What's harder to know is exactly why 
a particular SPI bus might not be available for use due to conflicts. Some 
processors take over control of the CS pin(s), and you can't "just" use a GPIO 
as another CS line. Add to that multiple software entities trying to use the 
SPI peripheral, and things can get impossible very fast.


-- 
Rick Mann
rm...@latencyzero.com


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[beagleboard] SPI and I2C port use?

2015-09-03 Thread Rick Mann 
I'm having trouble figuring out which SPI ports are available on the BBB if I 
want to continue to use the eMMC.

I also need to connect I2C and SPI to an audio codec IC. I think I can use any 
I2C/SPI port combination, right? Just might have to modify the driver a bit? 
I'm using the same codec as on the BBB Audio Cape.

But I was hoping there'd be an additional SPI port I could use for something 
else on my cape, and still be able to use the eMMC.

Lastly, the EEPROM is on I2C2, right? Can I share that with the audio codec? 
That would let me wire it the same as the Audio Cape, might make it easier to 
get the software working.

Thanks,

-- 
Rick Mann
rm...@latencyzero.com


-- 
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Re: [beagleboard] SPI and I2C port use?

2015-09-03 Thread Gerald Coley 
EEPROM is in I2C0 which does not connect to the expansion headers. I2C2 is
a shared bus. As long as no tow devices have the same address, you are
limited to 255 different devices on an I2C bus.

SPI has a dedicated CS line. You can and that with a GPIO pin and create
more CS signals if you like.

CODECS typically uses I2S which is a totally different animal. But there
are SPI and I2C CODECs out there.

Gerald

On Thu, Sep 3, 2015 at 6:34 AM, Rick Mann  wrote:

> I'm having trouble figuring out which SPI ports are available on the BBB
> if I want to continue to use the eMMC.
>
> I also need to connect I2C and SPI to an audio codec IC. I think I can use
> any I2C/SPI port combination, right? Just might have to modify the driver a
> bit? I'm using the same codec as on the BBB Audio Cape.
>
> But I was hoping there'd be an additional SPI port I could use for
> something else on my cape, and still be able to use the eMMC.
>
> Lastly, the EEPROM is on I2C2, right? Can I share that with the audio
> codec? That would let me wire it the same as the Audio Cape, might make it
> easier to get the software working.
>
> Thanks,
>
> --
> Rick Mann
> rm...@latencyzero.com
>
>
> --
> For more options, visit http://beagleboard.org/discuss
> ---
> You received this message because you are subscribed to the Google Groups
> "BeagleBoard" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to beagleboard+unsubscr...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
>



-- 
Gerald

ger...@beagleboard.org
http://beagleboard.org/

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