ADC configuration for LPC54616J512.

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ADC configuration for LPC54616J512.

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Contributor II

Hi,
I have successfully tested "lpc_adc_basic" sdk example for reading adc values on lpcXpresso54608 development board and its working.
I downloaded the sdk for LPC54616J512 and then started a new project for reading adc values using custom made LPC54616 board, but the output values is always 4095(high) (even when I try to read say 0 volts).
I have properly configured port and pins of ADC channel 3,4,5 and etc. I don't know if any clock configuration is needed.
PFA below of the zip containing the project for basic adc example.
It will very helpful if someone in the community is able to point me in the right direction.

Thanks & Regards,

Prathik.

6 Replies

16 Views
NXP TechSupport
NXP TechSupport

Hi Prathik Sargar,

I hope you are doing well,

Could you help me with the following inquiries  regarding your HW?

  1. Could you place the 0v signal closer to the  (or directly)  ADC pin , and repeat the test?
  2. When you changed the DEMO_ADC_SAMPLE_CHANNEL_NUMBER to test other channels, like channel 5, the ADC conversion  remained  on 4095, no matter the input signal?
  3. It could be useful to check if the MCU have the proper  ADC supply   and reference voltages  i.e VDDA, VSSS, VREFP, VRFEN.
  4.  Did you take a LPCxpresso board schematic as reference?

Similarly to your results with the LPCxpresso54608, I have not found issues running your code on the LPCxpresso54628.

Regards,

Diego.

16 Views
Contributor II

Hi Diego Charles,

Thanks for quickly replying to my query.
Hope You are doing well too.

Below are the details for your above inquiries,
1. I have placed 0v signal on ADC channel but output received is still 4095 units.
2. I have tested on ADC channel no. 3, 4, 5 and 11 but output remained as 4095 units no matter what the input signal!
3. Reference voltages details are as follows,
    a. VDDA = 3.3V
    b. VREFP = 3V
    c. VSSA = VSS
    d. VREFN = It is connected to VSS internally in chip. We are using 100-pin package.
4. Yes we have referred the same dev board schematic.

Thanks & Regards,

Prathik.

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16 Views
NXP TechSupport
NXP TechSupport

Hi Prathik,

In your example, the ADC is configured on Synchronous mode. It could be helpful to check if the system clock is working at the  expected frequency, determining if this is not causing the issue.

 

Could you help me with the following?

   1. Check the value of the  resulting conversion when the ADC channel 0 is selected

   Channel 0 is connected to the internal temperature sensor , which is initialized in the example that you    provided. For example,  at 24°C the conversion will be close 650.

   2. Do you have another custom board to test this ?

   3. Provide an screenshot of the ADC registers CTRL and SEQ-GDATA ( after a faulty conversion)

 

Also,  I am not aware if you received my previous email, regarding a ticket with the same inquire. Being that the case, please let me know, this will help us to avoid having information on two places.

Best regards,

Diego.

16 Views
Contributor II

Hi Diego Charles,

Sorry for replying so late but the issue is resolved now.

The Op-Amp used for signal processing was damaged and also the ADC reference voltage was not correct. That's why  the ADC was not working.

Thanks for helping me out.

Regards,

Prathik.

16 Views
NXP TechSupport
NXP TechSupport

Hi Prathik,

I am glad that the issue was resolved,

Have a great day and take care.

Diego.

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16 Views
Contributor I

Following up on this thread since we too have same problem.
Whenever we test LPCXpresso54608 sdk demo example it runs without any issue.
We successfully read analog values using adc example of LPCXpresso54608 development board but failed while doing it with lpc54616 board.
If you are able to figure it out please let us know the configuration that needs to be done!
thanks

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