About accuracy of TWR-KM34Z50's 24bit SDADC

cancel
Showing results for 
Search instead for 
Did you mean: 

About accuracy of TWR-KM34Z50's 24bit SDADC

Jump to solution
253 Views
romehuang
Contributor I

Hi I'm evaluating TWR-KM34Z50's 24bit SDADC, I wired both EXT_SD_ADP0 and EXT_SD_ADM0 to VSSA, and run afe_test, then I got values between 0x6df8 and 0x824a, it seems 13 bit shifting. Anything wrong in my configuration or is it normal?

Best Regards,

Rome.

0 Kudos
1 Solution
146 Views
Hui_Ma
NXP TechSupport
NXP TechSupport

Hi Rome,

When using the AFE demo default setting, the AFE channel0 value with bigger shifting. Please check below FreeMaster scope copy:

1.png

Then I change the default AFE module setting with max. oversampling number and low down AFE module refer clock with below code:

  AFE_ChanInit (CH0, AFE_CH_SWTRG_CCM_PGAOFF_CONFIG(DEC_OSR2048), 0, PRI_LVL0, NULL);

  AFE_Init     (AFE_MODULE_RJFORMAT_CONFIG(AFE_PLL_CLK, AFE_DIV256, 12288000));

After that, I will get below FreeMaster scope copy:

2.png

Wish it helps.


Have a great day,
best regards,

Ma Hui

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

View solution in original post

0 Kudos
2 Replies
147 Views
Hui_Ma
NXP TechSupport
NXP TechSupport

Hi Rome,

When using the AFE demo default setting, the AFE channel0 value with bigger shifting. Please check below FreeMaster scope copy:

1.png

Then I change the default AFE module setting with max. oversampling number and low down AFE module refer clock with below code:

  AFE_ChanInit (CH0, AFE_CH_SWTRG_CCM_PGAOFF_CONFIG(DEC_OSR2048), 0, PRI_LVL0, NULL);

  AFE_Init     (AFE_MODULE_RJFORMAT_CONFIG(AFE_PLL_CLK, AFE_DIV256, 12288000));

After that, I will get below FreeMaster scope copy:

2.png

Wish it helps.


Have a great day,
best regards,

Ma Hui

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

0 Kudos
146 Views
romehuang
Contributor I

Thanks for the answer, the shifting reduced dramatically.

Best Regards,

Rome.

0 Kudos