topic Re: imxRT1050 and ADC in i.MX RT Crossover MCUs

imxRT1050 and ADC

giannigrondona — Wed, 23 Jan 2019 16:43:07 GMT

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

Re: imxRT1050 and ADC

jeremyzhou — Thu, 24 Jan 2019 04:17:16 GMT

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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Re: imxRT1050 and ADC

giannigrondona — Thu, 24 Jan 2019 07:02:40 GMT

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

Re: imxRT1050 and ADC

jeremyzhou — Fri, 25 Jan 2019 02:47:11 GMT

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

Re: imxRT1050 and ADC

giannigrondona — Fri, 25 Jan 2019 07:37:03 GMT

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

Re: imxRT1050 and ADC

jeremyzhou — Mon, 28 Jan 2019 04:48:22 GMT

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

Re: imxRT1050 and ADC

giannigrondona — Mon, 28 Jan 2019 08:21:32 GMT

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

Re: imxRT1050 and ADC

jeremyzhou — Tue, 29 Jan 2019 03:13:02 GMT

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

Re: imxRT1050 and ADC

giannigrondona — Mon, 04 Feb 2019 14:06:39 GMT

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

Re: imxRT1050 and ADC

jeremyzhou — Wed, 06 Feb 2019 09:02:03 GMT

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

Re: imxRT1050 and ADC

AkshayWale — Tue, 11 Jan 2022 05:16:44 GMT

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

Re: imxRT1050 and ADC

imxrtuser — Tue, 11 Jan 2022 06:04:57 GMT

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