ADC not working in LPC546xx

[prasannanaik]

Hi,

 I am using LPC546xx development board OM13092 for evaluation.

I am using driver reference example "lpcxpresso54608_lpc_adc_interrupt" to check the performance of ADC in LPC546xx on analog channel 7(Port pin: PIO2_0,Pin 7 of J11 in revesion D board).

I have configured the port as analog but it is always giving 4059-4065 as ADC o/p even if i connect GND on channel 7).

I have attached the code for reference. Please help.

Thanks and best regards,

Prasanna

[prasannanaik]

Hi Jeremy,

Sorry I attached a different code. I was trying with channel 9 since I was not getting g proper output with channel 7. So my code for channel 7 is exactly same the only difference is what u pointed out..still the code is not working.

Thanks and best regards,

Prasanna

[jeremyzhou]

Hi Prasanna Naik,

Thanks for your reply.

Thanks for your reply.
Please set the PIO2_0 pin as the red box highlights before initializing the ADC.
So give a try.

Have a great day,
TIC

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[prasannanaik]

Hi Jeremy,

   I tried the suggested point but still it is not working.

I have added the following code after adc_configuration()

IOCON_PinMuxSet(IOCON,2,0,IOCON_FUNC0|IOCON_MODE_INACT|IOCON_ANALOG_EN|IOCON_INPFILT_OFF);

I have connected the ADC channel 7 to gnd(i.e shorted Pin 7 of J11 connector and pin 7 of connector J9) but i am getting ADC output as =~4060.

I think it's some sort of pin configuration issue,please help.

Thanks and best regards,

Prasanna

[jeremyzhou]

Hi Prasanna Naik,

Thanks for your reply.
In the lpc_adc_interrupt demo, I've added below codes in the BOARD_InitPins(), meanwhile, set the macro DEMO_ADC_SAMPLE_CHANNEL_NUMBER to 7.
Then, run the demo code, as Fig 1 shows, the demo works well.

Fig 1

Have a great day,
TIC

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[prasannanaik]

Hi jeremyzhou,

   I have following two queries:

   1) Which code have you added apart from "macro DEMO_ADC_SAMPLE_CHANNEL_NUMBER to 7"

   2) What have you shorted through that jumper in your attached image.

Thanks and best regards,

Prasanna

[jeremyzhou · Accepted solution]

Hi

Thanks for your reply.
Q1) Which code have you added apart from "macro DEMO_ADC_SAMPLE_CHANNEL_NUMBER to 7"?
-- Sorry for forgetting it,

    
    const uint32_t port2_pin0_config = (
                                         IOCON_PIO_FUNC0 |
                                         /* No addition pin function */
                                         IOCON_PIO_MODE_INACT |
                                         /* Input function is not inverted */
                                         IOCON_PIO_INV_DI |
                                         /* Enables digital function */
                                         IOCON_ANALOG_EN |
                                         /* Input filter disabled */
                                         IOCON_PIO_INPFILT_OFF |
                                         /* Standard mode, output slew rate control is enabled */
                                         IOCON_PIO_SLEW_STANDARD |
                                         /* Open drain is disabled */
                                         IOCON_PIO_OPENDRAIN_DI);
 
    IOCON_PinMuxSet(IOCON, 2U, 0U, port2_pin0_config);‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

  2) What have you shorted through that jumper in your attached image?
-- I use the line to connect the P2_0 to 3.3 V or Gnd for testing.

Have a great day,
TIC

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[prasannanaik]

Hi Jeremy,

   Thanks for your help.

   I was on leave so couldn't reply to your feedback.

   The actual problem was in connection of input signal. I didn't have schematic of the development board so i was connecting the signal to the wrong pin. The image of your board that u had attached triggered that thought.

Thanks and best regards,

Prasanna

[jeremyzhou]

Hi Prasanna Naik,

Thank you for your interest in NXP Semiconductor products and
for the opportunity to serve you.
After reviewing the attachment, I find that you select channel 9 instead of channel 7 to sample the analog input, so please check it.

#define DEMO_ADC_BASE ADC0
#define DEMO_ADC_SAMPLE_CHANNEL_NUMBER 9U
#define DEMO_ADC_IRQ_ID ADC0_SEQA_IRQn
#define DEMO_ADC_IRQ_HANDLER_FUNC ADC0_SEQA_IRQHandler
#define DEMO_ADC_CLOCK_DIVIDER 0U
#define PORT_PIN_CONFIG IOCON_BASE‍‍‍‍‍‍

Have a great day,
TIC

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