i.MX ProcessorsのトピックADC value read from user space

ADC value read from user space

nikhil_sahu2 — Thu, 30 Jul 2020 13:20:20 GMT

Hi Everyone,

I want to read the ADC value for the below pin ADC1_IN0 that we can read from the user space. my expetion is to get interface like sysfs gpio so i can export and use it.

Since this pin marked as Input so anyone suggest me how to read the value for this pin from userspace.

running linux (yocto zeus) on the imx board. One can access the datasheet from below link

https://www.nxp.com/docs/en/data-sheet/IMX6SXAEC.pdf (Page 137 Table 113).

Re: ADC value read from user space

igorpadykov — Fri, 31 Jul 2020 01:20:37 GMT

Hi Nikhil

unfortunately for i.MX6SX there is no linux adc support in nxp bsps and one can use FreeRTOS:

Windows Installer: i.MX 6SoloX FreeRTOS BSP 1.0.1 for Cortex-M4

Alternatively one can try to reuse i.MX7D linux adc driver, it is described in

sect.4.1.3 ADC Driver Overview i.MX Linux Reference Manual

Best regards
igor
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Re: ADC value read from user space

nikhil_sahu2 — Thu, 06 Aug 2020 05:34:49 GMT

Hi Igor1z‌,

Thanks for your reply. we are thinking to use three other gpio pins to meet our requirement. they are

NAND_DATA04 W7 NVCC_NAND GPIO ALT5 GPIO4_IO08 Input Keeper

QSPI1B_SS1_B F15 NVCC_QSPI GPIO ALT5 GPIO4_IO31 Input Keeper

SD2_DATA1 E14 NVCC_SD2 GPIO ALT5 GPIO6_IO09 Input Keeper

Could you please confirm in above three which one we can choose to read the gpio value for /sys/gpio/export functionality.

Also i would like to know how to calculate the GPIO no for above pins so i can control them using sysfs.

Thanks,

Nikhil

Re: ADC value read from user space

igorpadykov — Thu, 06 Aug 2020 06:07:09 GMT

Hi Nikhil

yes these pins can be used to read the gpio value for /sys/gpio/export functionality,

examples can be found on:

Definitive GPIO guide - Studio Kousagi Wiki

https://community.nxp.com/thread/381277

Best regards
igor