Accessing hardware on the Edison?

It seems there is no default user with the Yocto image.

root@MyEdison:/# cat /etc/passwd-
root::0:0:root:/home/root:/bin/sh
daemon:*:1:1:daemon:/usr/sbin:/bin/sh
bin:*:2:2:bin:/bin:/bin/sh
sys:*:3:3:sys:/dev:/bin/sh
sync:*:4:65534:sync:/bin:/bin/sync
games:*:5:60:games:/usr/games:/bin/sh
man:*:6:12:man:/var/cache/man:/bin/sh
lp:*:7:7:lp:/var/spool/lpd:/bin/sh
mail:*:8:8:mail:/var/mail:/bin/sh
news:*:9:9:news:/var/spool/news:/bin/sh
uucp:*:10:10:uucp:/var/spool/uucp:/bin/sh
proxy:*:13:13:proxy:/bin:/bin/sh
www-data:*:33:33:www-data:/var/www:/bin/sh
backup:*:34:34:backup:/var/backups:/bin/sh
list:*:38:38:Mailing List Manager:/var/list:/bin/sh
irc:*:39:39:ircd:/var/run/ircd:/bin/sh
gnats:*:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/bin/sh
nobody:*:65534:65534:nobody:/nonexistent:/bin/sh
messagebus:!:999:998::/var/lib/dbus:/bin/false
systemd-journal-gateway:!:998:995::/home/systemd-journal-gateway:/bin/sh
systemd-timesync:!:997:994::/home/systemd-timesync:/bin/sh
sshd:!:996:993::/var/run/sshd:/bin/false
rpc:!:995:992::/:/bin/false
rpcuser:!:994:991::/var/lib/nfs:/bin/false
pulse:!:993:1000::/var/run/pulse:/bin/false
root@MyEdison:/#

I see that the Tutorial at Sparkfun has them installing a Debian (Ubilinux) image.

https://learn.sparkfun.com/tutorials/loading-debian-ubilinux-on-the-edison#log-into-ubilinux

The link to the image file at Emutex still works.

https://emutex.com/products/ubilinux

mark

There is some interesting comments about harware in this document.

mraa: Intel Edison

So a little more playing

It seems that under /usr/bin there is mraa-gpio which is happy to run from the command line.

The options are.

root@edison:/usr/bin# mraa-gpio
Invalid command, options are:
list              List pins
set pin level     Set pin to level (0/1)
setraw pin level  Set pin to level (0/1) via mmap (if available)
get pin           Get pin level
getraw pin        Get pin level via mmap (if available)
monitor pin       Monitor pin level changes
version           Get mraa version and board name
root@edison:/usr/bin#

mraa-gpio version gives you

Version v1.0.0 on Intel Edison

while list

root@edison:/usr/bin# mraa-gpio list

00       J17-1: GPIO PWM
01       J17-2:
02       J17-3:
03       J17-4:
04       J17-5: GPIO
05       J17-6:
06       J17-7: GPIO I2C
07       J17-8: GPIO I2C
08       J17-9: GPIO I2C
09      J17-10: GPIO SPI
10      J17-11: GPIO SPI
11      J17-12: GPIO SPI
12      J17-13:
13      J17-14: GPIO
14       J18-1: GPIO PWM
15       J18-2: GPIO
16       J18-3:
17       J18-4:
18       J18-5:
19       J18-6: GPIO I2C
20       J18-7: GPIO PWM
21       J18-8: GPIO PWM
22       J18-9:
23      J18-10: GPIO SPI
24      J18-11: GPIO SPI
25      J18-12: GPIO
26      J18-13: GPIO UART
27      J18-14:
28       J19-1:
29       J19-2:
30       J19-3:
31       J19-4: GPIO
32       J19-5: GPIO
33       J19-6: GPIO
34       J19-7:
35       J19-8: GPIO UART
36       J19-9: GPIO
37      J19-10: GPIO
38      J19-11: GPIO
39      J19-12: GPIO
40      J19-13: GPIO
41      J19-14: GPIO
42       J20-1:
43       J20-2:
44       J20-3:
45       J20-4: GPIO
46       J20-5: GPIO
47       J20-6: GPIO
48       J20-7: GPIO
49       J20-8: GPIO
50       J20-9: GPIO
51      J20-10: GPIO
52      J20-11: GPIO
53      J20-12: GPIO
54      J20-13: GPIO
55      J20-14: GPIO

I tried setting GPIO 48 (pin 7 on the Arduino shield) and it wouldn't work.

If I used the echo command it worked, and using mraa-gpio get 48, it gave the current state (0 or 1) in response to the echo commands.

So I'm a little puzzled ... more digging is required.

mark

A little digging and this table shows that the mraa number and the GPIO number (and then the Arduino) are not the same.

mraa: Intel Edison

It seems mraa 33 is GPIO 48 and it works BUT.

You can use either the echo or the mraa-gpio to set the pin or change it,

BUT if you read the pin with get or getraw, you get a write error.

root@edison:/sys/class/gpio/gpio48# /usr/bin/mraa-gpio getraw 33
Pin 33 = 0
root@edison:/sys/class/gpio/gpio48# echo 1 > value
-sh: echo: write error: Operation not permitted
root@edison:/sys/class/gpio/gpio48# /usr/bin/mraa-gpio set 33 1
root@edison:/sys/class/gpio/gpio48# echo 0 > value
root@edison:/sys/class/gpio/gpio48# /usr/bin/mraa-gpio getraw 33
Pin 33 = 0
root@edison:/sys/class/gpio/gpio48# echo 0 > value
-sh: echo: write error: Operation not permitted
root@edison:/sys/class/gpio/gpio48#

Seems strange that a read (get) will lock out changing it but you can set it with one method and change it with the other ???

mark

I'm not a big fan of running everything as root. But I also appreciate that setting up a user with the right access levels is a non-trivial task

I just spotted UPM, runs on top of MRAA and provides a further abstraction so you can programme with LEDs and Light Sensors rather than working at the Pin level

https://github.com/intel-iot-devkit/upm

Workshopshedmcb1

You are touching upon some very interesting topics.

Thanks a lot.

I'm learning as I go. 

I've always said I'm more a hardware guy that pokes and prods at software.

I was hoping to get a head start on you guys/gals ...

Following our conversation yesterday ...

I did some searching and it turns out that the version of mraa-gpio is not the latest.

From here https://github.com/intel-iot-devkit/mraa

https://github.com/intel-iot-devkit/mraa#installing-on-intel-32bit-yocto-based-opkg-imageInstalling on Intel 32bit Yocto based opkg image

See the section below on compiling or use our repository to install on a glibc based yocto poky image that supports opkg.

Adding this repository is as simple as and you'll have the latest stable tagged build of mraa installed!

echo "src mraa-upm http://iotdk.intel.com/repos/3.5/intelgalactic-dev/opkg/i586" > /etc/opkg/mraa-upm.conf

opkg update

opkg install mraa

it took a few minutes

root@Edison_2:~# echo "src mraa-upm http://iotdk.intel.com/repos/3.5/intelgalactic/opkg/i586" > /etc/opkg/mraa-upm.conf
root@Edison_2:~# opkg update
Downloading http://iotdk.intel.com/repos/3.5/intelgalactic/opkg/i586//Packages.
Updated list of available packages in /var/lib/opkg/iotkit.
Downloading http://iotdk.intel.com/repos/3.5/iotdk/edison/all/Packages.
Updated list of available packages in /var/lib/opkg/iotdk-all.
Downloading http://iotdk.intel.com/repos/3.5/iotdk/edison/core2-32/Packages.
Updated list of available packages in /var/lib/opkg/iotdk-core2-32.
Downloading http://iotdk.intel.com/repos/3.5/iotdk/edison/edison/Packages.
Updated list of available packages in /var/lib/opkg/iotdk-edison.
Downloading http://iotdk.intel.com/repos/3.5/intelgalactic/opkg/i586/Packages.
Updated list of available packages in /var/lib/opkg/mraa-upm.
root@Edison_2:~# opkg install mraa
Upgrading mraa from 1.0.0-r0 to 1.5.1 on root.
Downloading http://iotdk.intel.com/repos/3.5/intelgalactic/opkg/i586/mraa_1.5.1_i586.ipk.
Removing package mraa-dev from root...
Removing package mraa-doc from root...
Removing obsolete file /usr/lib/libmraa.so.1.0.0.
Configuring mraa.
root@Edison_2:~# /usr/bin/mraa-gpio version
Version v1.5.1 on Intel Edison
root@Edison_2:~#

and now I have version 1.5.1

Mark

There's some tips and code in the book Jason mentioned, things like interrupts, pwm and memory mapped GPIO for high speed pulses

Exploring Edison by Harry Fairhead