imxRT1050 and ADC

[giannigrondona]

Hi

I need to learn how ADC  in imxRT1050 works in a short amount of time. Could  someone  tell  me a good Application note where ADC, EXTernal triggers and other features are explained in a easy  way? I also read microprocessor user Manual  but I find ADC module quite different from ADC used in LPC54608 so it is not easy to me to understand it.

Best Regards

Giovanni

[AkshayWale]

Hi @jeremyzhou ,

i am working imxrt1050 SDK ADC SAR interrupt example, Software trigger is enabled with resolution of 12bit and Reference voltage of 3.3v

ADC1 channel 0.

That means 3300/4096=0.85mv/count. i.e when i give a input signal of 0.85mv i get adc count as 1

I gave input of 1mv from calibrator theoritically i am suppose to get 1.24 counts, so practically 1 or 2 as adc counts.

but each i time i run the code, i am getting 1,2,128,69,78,23,...etc counts.

Please let me know what has to been done to get accurate counts? even for higher mv..i am getting lot of variations. 

Thank you

[giannigrondona]

Hi

I have another question about ADC.

ON chapter 65 of User Manual there is a note whom say "VREFH / VREFL are bonded to VDDA_ADC_3P3 / GND, on this device" and another document says that  VDDA_ADC_3P3  can go from 3.0 V to 3.6 V.

I'd like to connect VDDA_ADC_3P3 to an external Voltage Reference which tension is less than 3.0 V but it is 1024 milliVolt. Can ADC works works with 1024 mV as  External Voltage reference ?

Best Regards

Giovanni

[jeremyzhou]

Hi Giovanni Grondona,

Thanks for your reply.
1) Can ADC work with 1024 mV as  External Voltage reference?
-- No, it can't work.

Have a great day,
TIC

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[jeremyzhou]

Hi Giovanni Grondona ,

Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
I was wondering if you can point out which part in the RM make you confuse, maybe I can clarify it.
Have a great day,
TIC

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[giannigrondona]

Hi

I'd like to have  a simple example of  acquire a channel for example channel 0 with ADC. No hardware trigger but only software trigger. That could be a good starting point to understand how it works.

Thank you

Best Regards

Giovanni Grondona

[jeremyzhou]

Hi Giovanni Grondona,

Thanks for your reply.
I think the adc_polling demo which resides in the ~\SDK_2.5.0_EVK-MIMXRT1060\boards\evkmimxrt1060\driver_examples\adc\polling is just you want.
In this demo, typing any key into the debug console would trigger an ADC conversion and the trigger mode selects the software trigger.
Please refer to the demo for details.
Have a great day,
TIC

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[giannigrondona]

Hi Jeremyzhou,

Thank you for yor answer. I looked at the adc_polling demo and, yes it 's easy to understand. If I read  MIMXRT1060 User Manual  I find the external signals of ADC is from ADC 1_IN0 to ADC 1_IN15 and from ADC 2_IN0

to ADC 2_IN15, but signals ADC1_IN0 to ADC_IN15 share same pads  with ADC2_IN0 to ADC2_IN15 so I suppose I have 16 external signals for both ADC.

Adc polling_demo uses  ADC1 and channel 0 ( ADC1_IN0). In the same application could I use ADC2 and channel 0 ?. In that case what will be the input signal for channel 0 ? ( ADC2_IN0 share same pad with ADC1_IN0).

User manual tells each ADC can have up 8 external input but I have from ADC1_IN0 to ADC1_IN15

Could you clarify the association between external signals and ADC channels?.

Best Regards

Giovanni

[jeremyzhou]

Hi Giovanni Grondona,
1) In the same application could I use ADC2 and channel 0?
-- Yes, however, you need to do a bit modification.
2) In that case what will be the input signal for channel 0? ( ADC2_IN0 share the same pad with ADC1_IN0).
-- Yes, they share the same input pad。
3） Could you clarify the association between external signals and ADC channels?
-- It's a bit confusing, the ADC module supports up to 16 external analog inputs, however, it only supports up to sample 8 external analog inputs per once, as it only has 8 Control register for hardware triggers (ADCx_HCx).
Have a great day,
TIC

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[giannigrondona]

Hi

I have another question regarding ADC.

In the examples "adc_polling_demo" it 's used channel 0 in with software trigger. Only one channel is used in the example.

My question is

Can I use two or more channels  on same ADC:  some channels with hardware trigger and other channels with software trigger?  I read there is only on register on ADC  ( CFG register) where I can choose between hardware trigger and software trigger. That choice  ( hardware trigger, software trigger) concerns all the 8 analog inputs of same ADC ?

Best Regards

Giovanni Grondona

[imxrtuser]

Hi,

take a look at the ADC-ETC module. With that you can measure different channels and you can choose to use Software- or Hardware-Triggers.

https://community.nxp.com/t5/i-MX-RT/Understanding-ADC-ADC-ETC/m-p/1015784

Kind regards,

Stefan

[jeremyzhou]

Hi Giovanni Grondona,

Thanks for your reply.
1) Some channels with hardware trigger and other channels with software trigger?
-- No, it's impossible.
2) That choice  ( hardware trigger, software trigger) concerns all the 8 analog inputs of same ADC?
-- Yes, it does.
Have a great day,
TIC

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