Nerves starter project for Raspberry Pi
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Frank Hunleth
Apr 20, 2014, 10:24:46 PM4/20/14
to nerves-...@googlegroups.com
As part of an open source event at one of the local universities
yesterday, I put together a starter project for the students. It's a
simple project that toggles one of the Raspberry Pi's GPIO using
Elixir (thanks to Garth for a similar project on the BBB). The
instructions assume that you have a virtual machine that I don't have
posted on the web yet (it's 2GB), but that's only necessary if you're
running on Windows or Mac like was the case with the students. The
idea with the VM was both to make it possible for students to build a
embedded Elixir project on their laptops and to get something to them
that could be built in a reasonable amount of time. Regarding the
time, I had installed the pre-reqs for Nerves and downloaded most
tarballs before hand.
One of the big problems with Nerves is that it takes a long time to
get your first project working. As such, I believe that several people
have tried it out, but given up when there's an error or when the
first build takes too long. Buildroot has a similar issue and I don't
know the solution to this. If you distribute binaries, you run into
Linux-only issues and non-relocatable toolchains, so the obvious ways
seem to be out.
Unless better ideas pop up, I'll be updating the VM image and cleaning
up the starter kit docs. I certainly welcome help on this if there's
interest. Here's the current repo:
https://github.com/nerves-project/nerves-starter-kit
-Frank
--
Frank Hunleth
Troodon Software LLC
Embedded Software Development
http://troodon-software.com/
yesterday, I put together a starter project for the students. It's a
simple project that toggles one of the Raspberry Pi's GPIO using
Elixir (thanks to Garth for a similar project on the BBB). The
instructions assume that you have a virtual machine that I don't have
posted on the web yet (it's 2GB), but that's only necessary if you're
running on Windows or Mac like was the case with the students. The
idea with the VM was both to make it possible for students to build a
embedded Elixir project on their laptops and to get something to them
that could be built in a reasonable amount of time. Regarding the
time, I had installed the pre-reqs for Nerves and downloaded most
tarballs before hand.
One of the big problems with Nerves is that it takes a long time to
get your first project working. As such, I believe that several people
have tried it out, but given up when there's an error or when the
first build takes too long. Buildroot has a similar issue and I don't
know the solution to this. If you distribute binaries, you run into
Linux-only issues and non-relocatable toolchains, so the obvious ways
seem to be out.
Unless better ideas pop up, I'll be updating the VM image and cleaning
up the starter kit docs. I certainly welcome help on this if there's
interest. Here's the current repo:
https://github.com/nerves-project/nerves-starter-kit
-Frank
--
Frank Hunleth
Troodon Software LLC
Embedded Software Development
http://troodon-software.com/
Frank Hunleth
Apr 22, 2014, 9:50:20 AM4/22/14
to Josh Adams, Robby Clements, nerves-...@googlegroups.com
Hi Josh,
On Tue, Apr 22, 2014 at 9:11 AM, Josh Adams <josh.r...@gmail.com> wrote:
> Frank,
>
> Thanks for keeping us updated on NERVES. We just got together last night to
> play with it for the first time.
No problem. I'm quite happy to help, and it seems like getting things
working well on the Raspberry PI is the way to make the project more
accessible to lots of people.
I hope that you don't mind me cc'ing the Nerves mailing list since
there's one other person, Bill Babson, who was going to try out Nerves
on the Pi soon, and you guys may run into similar issues.
>
> We successfully built the SDK and built the starter kit project. We pushed
> it to an SD card and booted the Pi. We didn't get any blinking on port 22
> though, and debugging was hard because we don't have a USB TTL serial cable
> (this has exposed a weakness in our test rig)
In the Nerves SDK, there's a file
"board/raspberrypi/rootfs-additions/etc/erlinit.config" that specifies
whether to show the iex prompt on the UART pins or via the HDMI
output. I've been switching it back and forth, but I thought that I
settled on the HDMI output for now. If you change this file, run make
in the SDK directory to update the base image, and then run make in
the starter kit project to rebuild the starter kit image.
> Anyway, just wanted to give you a status update. We're going to hook up a
> monitor and keyboard to the thing sometime today and see if we can't
> troubleshoot it. What's the default login information in the builds?
No login. The starter kit boots straight to the iex prompt.
>
> Thanks again for the tool - really hoping we can get our stuff working with
> it. I know we'll have to figure out how to get the wifi working at a
> minimum, since they all depend on joining a network with the android device
> :)
Wifi will be fun. I haven't use wifi on the Raspberry Pi yet, so it
may take a little setup. I highly suspect that the wifi device drivers
aren't built by the Raspberry Pi's Linux kernel configuration that I'm
using. Running "make linux-menuconfig" in the SDK directory will let
you select them, but you may get lost in a sea of options if you
haven't done this before. If you don't see it, I probably can figure
it out pretty easily if you tell me what WiFi dongle you're using. (If
you figure it out let me know the config update, so that I can make
the default Raspberry Pi image from Nerves include them)
You'll also need to run "make menuconfig" in the SDK directory and
enable compilation of wpa_supplicant and wireless tools. Then, when
you're done building and can run the new image, use os:cmd to run the
following to bring up wireless.
ip link set wlan0 up
iwlist wlan0 scan
[use wpa_passphrase to generate a configuration for the wpa_supplicant]
wpa_supplicant -i wlan0 -c /tmp/wifi.conf
ip addr add 192.168.1.40/24 dev wlan0
The Arch Wiki has more details:
https://wiki.archlinux.org/index.php/Wireless_network_configuration
I've been using static IP addresses for all of my networking, but I
know that there's at least one user of DHCP among us. It's not too
hard to invoke udhcpc to get a dynamic address, but it hasn't been
wrapped into something that can be included in Nerves yet.
Hope this helps!
Frank
>
> More updates as we figure this stuff out,
>
> -Josh
>
>
> On Sun, Apr 20, 2014 at 9:31 PM, Frank Hunleth
> <fhun...@troodon-software.com> wrote:
>>
>> Josh, Robby,
>>
>> FYI. This might be of use to you for getting started with Nerves. See
>> github link at bottom. There are still a couple rough edges with
>> Raspberry Pi support, but it's getting better. Depending on what
>> you're doing, it might be fine, but let me know if you run into
>> issues.
>>
>> Thanks,
>> Frank
> --
> Josh Adams
On Tue, Apr 22, 2014 at 9:11 AM, Josh Adams <josh.r...@gmail.com> wrote:
> Frank,
>
> Thanks for keeping us updated on NERVES. We just got together last night to
> play with it for the first time.
No problem. I'm quite happy to help, and it seems like getting things
working well on the Raspberry PI is the way to make the project more
accessible to lots of people.
I hope that you don't mind me cc'ing the Nerves mailing list since
there's one other person, Bill Babson, who was going to try out Nerves
on the Pi soon, and you guys may run into similar issues.
>
> We successfully built the SDK and built the starter kit project. We pushed
> it to an SD card and booted the Pi. We didn't get any blinking on port 22
> though, and debugging was hard because we don't have a USB TTL serial cable
> (this has exposed a weakness in our test rig)
In the Nerves SDK, there's a file
"board/raspberrypi/rootfs-additions/etc/erlinit.config" that specifies
whether to show the iex prompt on the UART pins or via the HDMI
output. I've been switching it back and forth, but I thought that I
settled on the HDMI output for now. If you change this file, run make
in the SDK directory to update the base image, and then run make in
the starter kit project to rebuild the starter kit image.
> Anyway, just wanted to give you a status update. We're going to hook up a
> monitor and keyboard to the thing sometime today and see if we can't
> troubleshoot it. What's the default login information in the builds?
No login. The starter kit boots straight to the iex prompt.
>
> Thanks again for the tool - really hoping we can get our stuff working with
> it. I know we'll have to figure out how to get the wifi working at a
> minimum, since they all depend on joining a network with the android device
> :)
Wifi will be fun. I haven't use wifi on the Raspberry Pi yet, so it
may take a little setup. I highly suspect that the wifi device drivers
aren't built by the Raspberry Pi's Linux kernel configuration that I'm
using. Running "make linux-menuconfig" in the SDK directory will let
you select them, but you may get lost in a sea of options if you
haven't done this before. If you don't see it, I probably can figure
it out pretty easily if you tell me what WiFi dongle you're using. (If
you figure it out let me know the config update, so that I can make
the default Raspberry Pi image from Nerves include them)
You'll also need to run "make menuconfig" in the SDK directory and
enable compilation of wpa_supplicant and wireless tools. Then, when
you're done building and can run the new image, use os:cmd to run the
following to bring up wireless.
ip link set wlan0 up
iwlist wlan0 scan
[use wpa_passphrase to generate a configuration for the wpa_supplicant]
wpa_supplicant -i wlan0 -c /tmp/wifi.conf
ip addr add 192.168.1.40/24 dev wlan0
The Arch Wiki has more details:
https://wiki.archlinux.org/index.php/Wireless_network_configuration
I've been using static IP addresses for all of my networking, but I
know that there's at least one user of DHCP among us. It's not too
hard to invoke udhcpc to get a dynamic address, but it hasn't been
wrapped into something that can be included in Nerves yet.
Hope this helps!
Frank
>
> More updates as we figure this stuff out,
>
> -Josh
>
>
> On Sun, Apr 20, 2014 at 9:31 PM, Frank Hunleth
> <fhun...@troodon-software.com> wrote:
>>
>> Josh, Robby,
>>
>> FYI. This might be of use to you for getting started with Nerves. See
>> github link at bottom. There are still a couple rough edges with
>> Raspberry Pi support, but it's getting better. Depending on what
>> you're doing, it might be fine, but let me know if you run into
>> issues.
>>
>> Thanks,
>> Frank
> Josh Adams
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