[MinnowBoard] i2c support

Tony tony.makkiel at daqri.com
Thu Mar 10 15:55:15 UTC 2016


Hi John,
	Thank you very much for your help. It was a hardware fault on the 
controller board (solder actually). Now i2ctools are working after we 
reheated the joints.

Cheers,
Tony

On 07/03/16 21:33, John Hawley wrote:
> Inline & cutting down as this is getting a little long -JH
>
> On 03/07/2016 02:27 AM, Tony wrote:
>> I am not sure, why read fails. It is Minnowboard MAX.
>
> Since it's the MAX you are *LIKELY* running into a level shifter issue,
> which is obnoxious.  What device is this?  I'm happy to try and get one
> in to double check what's going on if you can let me know what you've got.
>
>> I tried running i2cdetect on bus 7 which fails with error
>>
>> "Error: Can't use SMBus Quick Write command on this bus"
>
> The bus itself doesn't support the Quick Write command so you need to
> add `-r` to the command line so that it doesn't actually try and do that.
>
> I'll add that info to the wiki (along with my suggestion on the
> i2cdetect and which bus you should look for) but some example code that
> might be helpful can be found here as well:
>
> https://github.com/MinnowBoard/minnow-max-extras/blob/master/calamari/calamari-i2c-eeprom.sh
>
>> Reading from address also fails
>>
>> "sudo i2cget -y 7 0x54 0x0c
>> Error: Read failed"
>>
>> Can the problem with level shifters be fixed on MAX boards?
>
> If it was the level shifters I'd expect something like "lost bus
> arbitration" not an absolute read failed.  Can you try the i2cdtect with
> the -r, and that attached, and let me know?  Again it would be helpful
> to know what chip, and I'll snag one and get it in.
>
> - John
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