[RFC] pH sensors

[RFC] pH sensors

[Matt Ranostay]

Hello et all,

So currently planning on working a I2C based pH sensor and want to get
some input on the iio_chan_type to use.

There are two solutions  that can be thought of:

1) Use the current IIO_CONCENTRATION type and use the percentage of
Hydronium (H3O+) in the solution to report to actual pH levels
2) New IIO_PH type that is an typically an integer from 0 (acid) - 14 (base)

Thanks,

Matt

Re: [RFC] pH sensors

[Matt Ranostay]

On Thu, Dec 3, 2015 at 8:29 PM, Matt Ranostay <mranostay@gmail.com> wrote:
> Hello et all,
>
> So currently planning on working a I2C based pH sensor and want to get
> some input on the iio_chan_type to use.
>
> There are two solutions  that can be thought of:
>
> 1) Use the current IIO_CONCENTRATION type and use the percentage of
> Hydronium (H3O+) in the solution to report to actual pH levels

I just remembered that pH is for example  -log(10**-7) = 7. so using
IIO_CONCENTRATION would require processing within the driver. So I
think option 2 is the only thing that makes sense since it would just
have a simple scaling value.

> 2) New IIO_PH type that is an typically an integer from 0 (acid) - 14 (base)
>
> Thanks,
>
> Matt

Re: [RFC] pH sensors

[Jonathan Cameron]

On 05/12/15 06:44, Matt Ranostay wrote:
> On Thu, Dec 3, 2015 at 8:29 PM, Matt Ranostay <mranostay@gmail.com> wrote:
>> Hello et all,
>>
>> So currently planning on working a I2C based pH sensor and want to get
>> some input on the iio_chan_type to use.
>>
>> There are two solutions  that can be thought of:
>>
>> 1) Use the current IIO_CONCENTRATION type and use the percentage of
>> Hydronium (H3O+) in the solution to report to actual pH levels
> 
> I just remembered that pH is for example  -log(10**-7) = 7. so using
> IIO_CONCENTRATION would require processing within the driver. So I
> think option 2 is the only thing that makes sense since it would just
> have a simple scaling value.
I'd have gone for the second option anyway!

Whilst it's nice to keep the range of units used to a minimum some units
are so ingrained in peoples minds for particular things we are best
going with them even when they could be blugeoned into an existing option!

> 
>> 2) New IIO_PH type that is an typically an integer from 0 (acid) - 14 (base)
>>
>> Thanks,
>>
>> Matt
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