The design I'm using is using ADC2 channel 3. This ADC pin does not work correctly. To double check if there was a design issue, when this pin is used on the MIMXRT1020-EVK it still does not work. R249 and R251 are removed so that it is not connected to a pull up. The behavior I see is it appears to be pulled up and increases up to and stays at a value of ~2700. A square wave running at 1khz from an oscilloscope is put onto the header at J19 pin 10. This input is used on J18 pin 1 when using channel 10.
I used the evkmimxrt1020_adc_12b1msps_sar_interrupt example from the sdk as it most closely represents the settings I'm using in my design.
This is the config I used with the sdk:
#define DEMO_ADC_BASE ADC2
#define DEMO_ADC_IRQn ADC2_IRQn
#define DEMO_ADC_USER_CHANNEL 3U
#define DEMO_ADC_CHANNEL_GROUP 0U
#define EXAMPLE_ADC_IRQHandler ADC2_IRQHandler
Pin configuration with the pins tool for [90] GPIO_AD_B1_02:
Peripheral: ADC2
Signal: IN, 3
Slew Rate: Slow
Software Input On: Disabled
Open Drain: Disabled
Speed: Medium
Drive Strength: RO/6
Pull/Keeper select: Keeper
Pull/Keeper enable: Disabled
Pull Up/Down Config: 100k Ohm Pull Down
Hysteresis: Disable
Using [90] GPIO_AD_B1_10 with the same configuration above,
but for signal IN, 10 works. The only change in software is made to:
DEMO_ADC_USER_CHANNEL 10U
Both pins are enabled for the test but only one is used at a time.
I tried many settings to get some sort of response from the pin, but
it never returns a reasonable value.
In ADC_Init, I added this above "base->CFG = tmp32;" and tested all
of the values for the averaging:
// kADC_HardwareAverageCount4 = 0U, /*!< For hardware average with 4 samples. */
// kADC_HardwareAverageCount8 = 1U, /*!< For hardware average with 8 samples. */
// kADC_HardwareAverageCount16 = 2U, /*!< For hardware average with 16 samples. */
// kADC_HardwareAverageCount32 = 3U, /*!< For hardware average with 32 samples. */
// kADC_HardwareAverageDiasable = 4U, /*!< Disable the hardware average function. */
tmp32 |= ADC_CFG_AVGS(kADC_HardwareAverageCount8);
base->CFG = tmp32;
I did this with and without enabling averaging to try and find
one working setting:
tmp32 |= ADC_GC_AVGE_MASK;
base->GC = tmp32;
I'm looking for a way to get this pin working and would appreciate any help!
MCUXPresso 11.9.0
SDK 2.15.0
Problem occurs with the MIMXRT1020-EVK board as well as the MIMXRT1021DAG5A chip in the design.
Got the SD mixed up with the AD signal bank. Thanks!
Hi @joshgentrycargt ,
Thank you for your updated information.
I down load your project, and add print information, ADC2 channel3 work normal.
ADC2 channel3 connect AREF.
ADC2 channel3 connect GND.
Please be aware that ADC2 channel3 PIN is PIN90（GPIO_AD_B1_02）, This pin is not connect to J19 pin 10(GPIO_SD_B1_02).
I connect one end of resistor R85(Connect PIN90) with a wire harness, and the other end to GND or AREF.
Wish it helps you.
If you still have question about it, please kindly let me know.
Best Regards
mayliu
I made your changes to this project and still see the same results. Attached is my workspace. I also attached a version of adc_interrupt.c that fills a buffer instead of using getchar. I'm using a mag wire connected to J19 pin 10 to drive ADC2 channel 3.
Hi ,
Thank you for your interest in the NXP MIMXRT product, I would like to provide service for you.
I used the MIMXRT1020-EVK board to verify ADC1 channel 0 and ADC2 channel 3, and the ADC conversion results are normal without any issues.
1：Please open the Pins Tool, and Set ADC2 channel3, and click Update Code button.
2: In the Project " evkmimxrt1020_adc_12b1msps_sar_interrupt"
Please add code as what I do.
The image below shows the results of my validation.
Wish it helps you.
If you still have question about it, please kindly let me know.
Best Regards
mayliu