GPIO issue with some pins

lucarossetto

Hi all,

I have to set some pins of the gpio to use them as output with the mraa library (with python) to use a hat; the pins are:

MRAA no.	Function	Rpi GPIO	Sysfs GPIO	mraa device
11	UART_RTS	17	478	UART0
13	GPIO(27)	27	432
15	GPIO(22)	22	431
16	PWM3	23	471	PWM3

Extract from https://github.com/eclipse/mraa/blob/master/docs/up2.md#pin-mapping

I'm using ubuntu 20.04 and kernel 5.4
uname -a:

Linux es 5.4.0-1-generic #0~upboard5-Ubuntu SMP Fri Jan 7 11:53:57 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

lsb_release -a:

Distributor ID: Ubuntu
Description:    Ubuntu 20.04.6 LTS
Release:        20.04
Codename:       focal

mraa-gpio version:

Version v2.1.0 on Unknown platform

I followed the kernel installation guide (https://github.com/up-board/up-community/wiki/Ubuntu_20.04#install-ubuntu-kernel-540-from-ppa-on-ubuntu-2004) and the mraa guide (https://github.com/eclipse/mraa#installing-on-ubuntu *except for node-mraa for which the installer couldn't find a candidate)

I have also set in bios the pins as gpio (and not pwn3 or uart) and configured this as output:

As I wrote before I need to command the 4 gpio pins, but 2 works correctly (pin 11, 16) and two do not (pin 13, 15)
This is the script:

#!/usr/bin/env python

# Author: Manivannan Sadhasivam <[email protected]>
# Copyright (c) 2018 Linaro Ltd.
#
# SPDX-License-Identifier: MIT
#
# Example Usage: Toggles GPIO 23 and 24 continuously in an alternative pattern

import mraa
import time

# initialise gpio
gpio_1 = mraa.Gpio(432, owner=False, raw = True)

gpio_2 = mraa.Gpio(430, owner=False, raw = True)
# set gpio to output
gpio_1.dir(mraa.DIR_OUT)

# set gpio to input
gpio_2.dir(mraa.DIR_IN)

# toggle gpio
while True:
    gpio_1.write(1)

    time.sleep(1)

    print(gpio_2.read())

    gpio_1.write(0)

    time.sleep(1)

    print(gpio_2.read())

I tried with system command too

echo 432 > /sys/class/gpio/export 
echo out > /sys/class/gpio/gpio432/direction
echo 1 > /sys/class/gpio/gpio432/value 

For pin 11 and 16 all works and I see the output to 3,3V but for pin 13 and 15 the command seems to be written but the output remain to 0V

Someone can help me?

Thanks a lot for your help

garyw

@lucarossetto
the pin13,15 is ADC 2,3 also, you may need disable ADC channel 2&3 in BIOS too.

the other simple way is using the latest pinctrl-upboard driver (no need up kernel),
you can refer my comment in other thread, it's fully control under OS no need modify BIOS in the latest pinctrl-upboard driver.

https://forum.up-community.org/discussion/comment/13367#Comment_13367

lucarossetto

@garyw
Hi, thanks for the replies
My board is a UPS-APLX7F-A20-0464, and from this documentation (https://github.com/up-board/up-community/wiki/40Pin-Header) only the pro version have the adc input, anyway i search in all pages of BIOS and
except for the screens in the previous post I don't find other settings for gpio/ADC

I tried also the steps in the other thread but mraa don't find any pin, i attach all commands and console output

garyw

@lucarossetto
try to restore BIOS default and please check does the pinctrl-upboard driver loaded as below screenshot

lucarossetto

@garyw
After bios reset all works, but i have only one problem the pin 16 is a pwm output and during boot it's set (probably) at 50%. It's possible set a boot (default) value and type (gpio/uart/pwm) for each pin?

Thank you

garyw

@lucarossetto
about pin 16 boot default value you can try to set pin 16 output high in BIOS, then boot into OS when pinctrl driver loaded you can control it by your app.