linux-kernel - Re: [PATCH 2/2] iio: adc: ti_am335x_tscadc: Improve accuracy of measurement

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Message-ID: <20181128091432.GT4272@dell>
Date:   Wed, 28 Nov 2018 09:14:32 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Vignesh R <vigneshr@...com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio@...r.kernel.org, linux-omap@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] iio: adc: ti_am335x_tscadc: Improve accuracy of
 measurement

On Mon, 19 Nov 2018, Vignesh R wrote:

> When performing single ended measurements with TSCADC, its recommended
> to set negative input (SEL_INM_SWC_3_0) of ADC step to ADC's VREFN in the
> corresponding STEP_CONFIGx register.
> Also, the positive(SEL_RFP_SWC_2_0) and negative(SEL_RFM_SWC_1_0)
> reference voltage for ADC step needs to be set to VREFP and VREFN
> respectively in STEP_CONFIGx register.
> Without these changes, there may be variation of as much as ~2% in the
> ADC's digital output which is bad for precise measurement.
> 
> Signed-off-by: Vignesh R <vigneshr@...com>
> ---
>  drivers/iio/adc/ti_am335x_adc.c      | 5 ++++-

>  include/linux/mfd/ti_am335x_tscadc.h | 4 ++++

Acked-by: Lee Jones <lee.jones@...aro.org>

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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