How to configure GPIO and toggle led on apalis imx 8 (torizoncore)using python

Technical Support
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1

Hi,
I am trying to toggle led using GPIO on apalis imx8(apalis eval board) using python
Please let me know some pointers on how to configure the same.

Thanks,
Shardul

How to know the gpio numbers
2

Hi @ShardulC ,

Thanks for writing Toradex Community!

One can install pyhton package for libgpiod that is python3-libgpiod in application container. python3-libgpiod can be used with in python script to manage gpio lines.

sudo apt update
sudo apt install python3-libgpiod

For example, let’s assume we need to access MXM3 X1 pin 5 (Apalis GPIO3) from an Apalis iMX8, which is accessible at LSIO.GPIO0_IO12 . This means we need to access GPIO bank 0 line 12.
Here is the short python script to make the pin logic high

import gpiod

chip=gpiod.Chip('gpiochip0')
lines = chip.get_lines([ 12 ])
lines.request(consumer='gpio', type=gpiod.LINE_REQ_DIR_OUT)
lines.set_values([ 1 ])

Important: While running docker run it is important to pass gpio chip so that can be accessed inside container.

Please check below article for more detail.

Let me know if you face any issue.

Best Regards
Ritesh Kumar

3

Hey @ShardulC -

I work in C#/C++ but I found the hard part was identifying the bank and line for a given header pin on the carrier board. Here is my recipe using the iMX8 and Ixora board. The algorithm should be the same for your hardware.

// To find bank and line:
// 1. Identify pin on carrier board. Sample code is using GPIO1 which is pin 13 on X27 connector
// on Ixora carrier board.
// 2. From carrier board data sheet, find MXM3 pin, here it’s pin 1
// 3. From the SOM data sheet, identify the GPIO bank and line for the given pin
// Most of the SOM pins have multiple uses. Look for the LSIO.GIPOx.IOyy entry in the
// alternate functionality columns. For pin 1, alt3 has LSIO.GPIO0.IO08 which corresponds
// to bank 0, line 8. ^ ^^

// For the Ixora carrier board:
// Name X27 pin MXM3 pin Bank Line
// GPIO1 13 1 0 8
// GPIO2 14 3 0 9
// GPIO3 15 5 0 12
// GPIO4 16 7 0 13
// GPIO5 17 11 4 1
// GPIO6 18 13 4 2
// GPIO7 19 15 3 26
// GPIO8 20 17 3 28

Also, you will need to expose the appropriate driver to your system. I’m using pins on bank 0 so I exposed /dev/gpiochip0.

Good luck!
Jeff

4

Hi @ritesh.tx Thanks for the reply. I tried following steps..

  1. Ran the command …
    docker run --rm -it --device /dev/gpiochip0 torizonextras/arm64v8-gpiod

  2. Ran commands you mentioned in the open container..
    sudo apt update
    sudo apt install python3-libgpiod

  3. created a file in nano editor led.py with following…
    import gpiod

chip=gpiod.Chip(‘gpiochip0’)
lines = chip.get_lines([ 12 ])
lines.request(consumer=‘gpio’, type=gpiod.LINE_REQ_DIR_OUT)
lines.set_values(1)

  1. on running python3 led.py… I am getting..
    lines.set_values(1)
    TypeError: Number of values must correspond with the number of lines

Any clues/pointers about this..

Thanks,
Shardul

How to import GPIO and toggle led on apalis imx 8 using Visual Studio Code as compiler
5

Hi @ShardulC ,

Please check we have updated the reply for lines.set_values([ 1 ]).

Let us know if this also not working for you.

Best Regards
Ritesh Kumar

6

@jpinterp Thanks a lot for help..could understand the relation between eval board pins and corresponding imx8 functions with the details provided. Led toggle worked.

Thanks,
Shardul

7

Thanks a lot @ritesh.tx Led functionality worked with the python sample provided.

Thanks,
Shardul