A/D Gain and bias erros can be software corrected, but linearity cannot, it's the limiting factor in A/D performance.

this is assuming you are using the word linearity as the max difference between a straight line and the measured A/D output throughtout the A/D range

--- In m..., "paddu.koti" wrote:
>
> Hi,
>
> I need your help regarding MSP430's ADC.
>
> I am testing ADC in MSP430F54xx using internal REF,
> but found that linearity is not good,I am getting a difference of about 4%.
> Please let me know if there is a solution to overcome this or if there is any application note from TI.
>
> Thankyou in advance
>
> Regards.
> Paddu
>

Beginning Microcontrollers with the MSP430

Hey Guys,
I needed to know about the ADC calibration data awhile ago, and asked TI about it's
location on the F5438 chip. Below is their response:
For the older 2xx chips, the calibration data was located in INFOA, which could be erased (even though that section of memory has a lock-feature). The 5xx series is different. The calibration data is located in flash memory but it cannot be written to or erased. The 5xx User's Guide (page 33 -- section 1.9) shows the memory map in a tabular form. From page 86 of the 5438 datasheet shows the calibration info to be located at 0x01A00. The table in the User's Guide indicates this section cannot be erased and a PUC reset is generated if that section of memory is accessed.
Good luck with your linearity problems,
Mike Raines

________________________________
From: m... [mailto:m...] On Behalf Of Michael
Sent: Thursday, October 29, 2009 9:12 AM
To: m...
Subject: [msp430] Re: MSP430 ADC Linearity

Hello Paddu,
> I am testing ADC in MSP430F54xx using internal REF, but found that
> linearity is not good,I am getting a difference of about 4%.
I guess the first question would be how you measured this (what's the error inherent to your measurement setup).

> Please let me know if there is a solution to overcome this or if
> there is any application note from TI.
I know the F2xx devices come with ADC calibration data in the INFO FLASH (segment A?) from factory. It makes sense the F5xx should have it too, if you haven't erased the info flash. Check the documentation.

Regards,
Michael K.

--- In m..., "paddu.koti" wrote:
>
> Hi,
>
> I need your help regarding MSP430's ADC.
>
> I am testing ADC in MSP430F54xx using internal REF,
> but found that linearity is not good,I am getting a difference of about 4%.
> Please let me know if there is a solution to overcome this or if there is any application note from TI.
>
> Thankyou in advance
>
> Regards.
> Paddu
>

Hello Paddu,
> I am testing ADC in MSP430F54xx using internal REF, but found that
> linearity is not good,I am getting a difference of about 4%.
I guess the first question would be how you measured this (what's the error inherent to your measurement setup).

> Please let me know if there is a solution to overcome this or if
> there is any application note from TI.
I know the F2xx devices come with ADC calibration data in the INFO FLASH (segment A?) from factory. It makes sense the F5xx should have it too, if you haven't erased the info flash. Check the documentation.

Regards,
Michael K.
--- In m..., "paddu.koti" wrote:
>
> Hi,
>
> I need your help regarding MSP430's ADC.
>
> I am testing ADC in MSP430F54xx using internal REF,
> but found that linearity is not good,I am getting a difference of about 4%.
> Please let me know if there is a solution to overcome this or if there is any application note from TI.
>
> Thankyou in advance
>
> Regards.
> Paddu
>

Hi,

I need your help regarding MSP430's ADC.

I am testing ADC in MSP430F54xx using internal REF,
but found that linearity is not good,I am getting a difference of about 4%.
Please let me know if there is a solution to overcome this or if there is any application note from TI.

Thankyou in advance

Regards.
Paddu