tvi.al

Crafting connected watches @ TAG Heuer agile manager, quadcopter builder & musician

Featured Posts

04March

read

Moving to HTTPS when using external images

This blog run LetsEncrypt certificates for few months now without any issue. That's why I decided to move another web project to full HTTPS.

Moving to HTTPS is easy

Thank you LetsEncrypt.
I won't explain here how to get/install/renew certificates since a lot of web pages cover this topic already.

All these docs make the move from HTTP to HTTPS pretty easy.

But more complicated when using external media

I have a web project where the main content of each page is a picture coming from anywhere over the Internet. These media are chosen by the end-user himself, based on suggestions from a search API like Bing or Google.

The problems I faced where the following:
- the APIs do not provide a way to only ask media secured by HTTPS - I could filter urls on my side but the number of results using HTTPS is pretty low (<10% on the tests I made) - these external media may fallback to HTTP when they want - of course I can't do anything on these external websites

What will be the problem of loading HTTP images in a HTTPS website?

This is called mixed content and is generally visible in you browser console under this message:

Mixed Content: The page at 'https://www.my-site.com/' was loaded over HTTPS, but requested an insecure script 'http://www.my-site.com/something-called-using-http'. This request has been blocked; the content must be served over HTTPS.

This is visible in the browser with the following symptoms:

the media is not loaded, pretty annoying when this is the main content of your page
you loose the "Secured" green locker in the address bar

Source: https://scotthelme.co.uk/still-think-you-dont-need-https/

What's the solution?

The best solution I found is to rely on an Open Source project named camo. It's a proxy written in CoffeeScript & Ruby which will allow to use your secured domain to get content from anywhere on the Internet.

Camo is all about making insecure assets look secure. This is an SSL image proxy to prevent mixed content warnings on secure pages served from GitHub.

This project has been used by Github itself to secure external content.

A Ruby and a PHP clients are available. These library sign and encrypt URLs passed to camo to secure proxy usage.

Camo is pretty easy to install and run. The only issue is that you will get the trafic for these images and you bandwidth may suffer (but using Amazon Cloudfront on top of that may fill your needs)

If you find this article useful, or have another approach to cover mixed content when using external media, leave a comment.

18December

read

Parrot Mambo FPV

Show Comments Thomas VIAL

To tell you the truth, I avoided Parrot for years because all their drones were controlled by bluetooth from a smartphone... This was clearly not practical nor precise, and the range was pretty small.

But you may not know that the core DNA of Parrot is bluetooth, especially car connectivity and they're quite good in this domain, and they work with major car manufacturers.

A new hope

Last December, I visited Parrot website because I was looking for a indoor drone and I discovered the Mambo which looked great. Still using bluetooth, BUT Parrot also created a great controller called "FlyPad".

#oopsididitagain #parrot #mambo joined the family

Une photo publiée par Thomas (@tomav) le 11 Déc. 2016 à 7h45 PST

And it's Awesome, like PS4 paddle but heavier.

Parrot Mambo Drone

The Parrot Mambo is an excellent quadcopter to start with to fly indoor because it offers a great stabilization, the size is perfect (not to big/small), works perfectly with the FlyPad, has software upgrades, some with pre-configured flips and rolls, 6 minutes flight time which is cool for drones in this size range.

It also offers 2 lightweight accessories plugged with powered LEGO connector on the top of the drone, the "cannon" and the "grabber". I did not spent a lot of time using them but they may let you imagine some challenges with your friends.

You will really have fun flying this drone.

But few things are still missing

a configuration option to disable stabilization. Doing a front-flip using a button is cool, but we'd like to do it manually after some time. I opened a feature request on Parrot Forums (french) in case you want to support.
a FPV cam/vtx! This may be an option in the future...

But the good new, is that you can easily do it yourself!

FPV Upgrade

Here are the steps I followed to add a FPV cam/vtx to the Parrot Mambo:

order the Eachine TX02 5.8G 40CH (~25€, weight is only 5g). Exists in 25/200/600mw
get 2 small bullet connectors from one of LEGO (yes you have to destroy one, I was not able to find them on the market)
solder the bullet connector to the red and black camera wires
get small LEGO bricks and use double-sided tape to place the camera on front
plug this on the front LEGO row, and then plug the bullet connectors into the last row (when looking to the drone from the rear, red wire on the left hole, and black on right)
configure the FPV channel on the video transmitter and on your receiver (goggles or screen)

You're done. Enjoy immersion flights with your Parrot Mambo FPV!

#parrot #mambo #fpv #parrotmods - cc @parrot_official #diy

Une photo publiée par Thomas (@tomav) le 8 Janv. 2017 à 4h52 PST

Notes

Note that this does not really affect the flight time, perhaps one minute.
Since I wrote this article, I found the BoosterDrones Eye FPV Mambo which seems to be a good alternative. That said, the 3d printed part seems pretty cheap.
UPDATE: in september 2017, parrot released a FPV version of his Mambo mini drone, available on its official website.

11October

read

Setup Headtracking with Skyzone SKY-01 and Futaba T8J

Show Comments Thomas VIAL

When I wanted to get headtracking with my Skyzone SKY-01, I thought it would be as easy as plug & play. But it's not.

I found a lot of partial information over the internet, and wanted to share with a more complete version.

The configuration has to be done:

on the Skyzone Goggles AND
on your Futaba transmitter

Note that I'm using the following setup on my TBS Discovery:

DJI Naza-m V2
Zenmuse H3-2D with GoPro Hero4 Silver (no pan, only tilt)

Skyzone configuration

We begin with the goggles. By default, they use channel 5 for pan and channel 6 for tilt.

To change this setting:

Press and Hold Button "TRACK", then connect power to enter Head Tracker Setup Menu (Release as soon as beep). Head Tracker beeps indicating the current PPM Channel. See details below.
Short Press "TRACK" Button to select different PPM Channels

Here are the Beep PPM Channel:

1 short beep Pan CH5, Tilt CH6 (Factory default)
2 short beep Pan CH5, Tilt CH7
3 short beep Pan CH5, Tilt CH8
4 short beep Pan CH6, Tilt CH7
5 short beep Pan CH6, Tilt CH8
6 short beep Pan CH7, Tilt CH8

In my case, I wanted to use channel 8, so 5 and 6 beeps are both valid options.
You can now unplugged the power cable.

Your goggles are now configured!

Futaba configuration

This was the tricky part for me. But now I can explain you how to do.

Trainer

Long Press on +
Go to third screen
Select TRAINER
TRAINER master must be set to OFF
Every channel can be turned OFF, except channel 8:AU2, which needs to be set to FNC. It will be used to the Skyzone tilt.

Exit with END.

P.MIX1-6

Now go to P.MIX1-6 and:

Create a new mix on the first slot
Set RATEL and H to -100%
MASTER to AU2 (we take the tilt channel 8)
SLAVE to GER (we route it to the GER, channel 5)
SW to SwH (it is the Trainer Switch of the Futaba T8J)
POSI to DOWN (when switch will be down, headtracking will be enabled)

Exit with END, twice.

Tests

To enable your headtracker, you have to push the H switch. This switch cannot be blocked in the active position without a trick (see bellow).

When you active this switch, you can move your head up and down and your gimbal will follow.

Note that you have a TRACK button on your goggles. It allows you to reset the center position with a short press.

28September

read

Generate UML diagrams under OSX

Show Comments Thomas VIAL

If you work in IT, you probably want to generate UML diagrams.
There are a lot of way to do that, but some may require proprietary softwares.

I had a look to some of them, and chose to explain the easiest ways I found using Open Source librairies (if you're a minimum techie)

The recommended tools are:

Scruffy, used on yUML.me online service
PlantUML, used by Mediawiki and others softwares

They won't fit the same usage / needs, so you should have an idea of what you need :-)

Scruffy

I discovered yUML.me mid-2014 when I started to work with Neo4j.
It's an amazing online tool, really easy to use for simple graphs.

Scruffy is the library used behind yUML.me, and is available for download/fork on Github.

But Scruffy:

is was hard to install because of dependencies
won't fit for complex graphs

I sent a Pull Request to explain of to install Scruffy under Mac OSX and here the detailed version:

install Homebrew
install graphviz and plotutils

brew install graphviz plotutils
brew install imagemagick --with-librsvg
if you haven't pip yet

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py sudo python get-pip.py
install scuffy and image (PIL replacement)

sudo pip install image scruffy

You can now use Scruffy, here's a basic example:

suml --png --font-family Purisa --scruffy "[Node A]->[Node B],[Node B]->[Node C],[Group [Node A][Node B]]" > test.png

Will generate:

PlantUML

Their website is really oldschool... yes. But this tool allows you to generate complex and real <uml> diagrams.

I personally use SublimeText as text editor / IDE, and Jayson Vantuyl created a plugin to generate you diagrams directly from this IDE.

The install guide available on Github is clear if you use SublimeText. Sorry, but I won't cover other IDE here, but PlantUML provides useful links.

Here is an activity diagram example:

@startuml
(*) --> if "Some Test" then
  -->[true] "activity 1"
  if "" then
    -> "activity 3" as a3
  else
    if "Other test" then
      -left-> "activity 5"
    else
      --> "activity 6"
    endif
  endif
else
  ->[false] "activity 2"      
endif
a3 --> if "last test" then
  --> "activity 7"
else
  -> "activity 8"
endif
@enduml

(Looks like basic code, isn't it?)

Will generate:

There are many kinds of diagrams that can be generated with PlanUML.

12September

read

How to fix the Gamin/FAM issue

Show Comments Thomas VIAL

On my docker mail server, I experienced the following problem connecting to my IMAP server:

# Telnet authentication
$ telnet 192.168.59.103 143
Trying 192.168.59.103...
Connected to 192.168.59.103.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION STARTTLS] Courier-IMAP ready. Copyright 1998-2011 Double Precision, Inc.  See COPYING for distribution information.
a1 LOGIN user@domain.tld mypassword
* OK [ALERT] Filesystem notification initialization error -- contact your mail administrator (check for configuration errors with the FAM/Gamin library)
a1 OK LOGIN Ok.

As you can see, the authentication succeeded but a alert message appears.
As you can also see, the error is "client side". Nothing appears on my server logs.
I used libfam0 and fam daemon on an Ubuntu Trusty docker image.

Use gamin instead of fam

This is what is said about gamin on the Ubuntu website:

libgamin0
  Client library for the gamin file and directory monitoring system
or libfam0
  Client library to control the FAM daemon also a virtual package provided by libgamin0

I moved from fam to gamin:

apt-get install gamin

But the error moved from client side to server side.

imapd: Failed to connect to socket /tmp/fam--

I read a lot of posts over the Internet and many problems have been resolved installing gamin.
So I supposed that I had another problem.

So, especially if you are a docker user, read the next part.

Use a "real" unix user

In my postfix configuration, I forced the ownership of my mail data like this:

# Mail directory
virtual_mailbox_base = /var/mail
virtual_mailbox_domains = /etc/postfix/vhost
virtual_mailbox_maps = hash:/etc/postfix/vmailbox
virtual_alias_maps = hash:/etc/postfix/virtual
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000

The "problem" is that I did not have a unix user with uid 5000.
Without a real user, the gam_server daemon won't start.

I added a specific unix user with the appropriate uid and everything went OK, client and server side.

The short version, to summarize

If you experience one of these errors:

# Client Side, visible when trying to authenticate on the IMAP server using telnet
Filesystem notification initialization error -- contact your mail administrator (check for configuration errors with the FAM/Gamin library)

# Server Side, usually in /var/log/mail.log
imapd: Failed to connect to socket /tmp/fam--

Here is what you need to do:

Install gamin instead of fam,
Verify that your files are owned by an existing / real unix user, otherwise, gam_server won't start

Show Comments Thomas VIAL

This blog run LetsEncrypt certificates for few months now without any issue. That's why I decided to move another web project to full HTTPS.

Moving to HTTPS is easy

Thank you LetsEncrypt.
I won't explain here how to get/install/renew certificates since a lot of web pages cover this topic already.

All these docs make the move from HTTP to HTTPS pretty easy.

But more complicated when using external media

What will be the problem of loading HTTP images in a HTTPS website?

This is called mixed content and is generally visible in you browser console under this message:

Mixed Content: The page at 'https://www.my-site.com/' was loaded over HTTPS, but requested an insecure script 'http://www.my-site.com/something-called-using-http'. This request has been blocked; the content must be served over HTTPS.

This is visible in the browser with the following symptoms:

the media is not loaded, pretty annoying when this is the main content of your page
you loose the "Secured" green locker in the address bar

Source: https://scotthelme.co.uk/still-think-you-dont-need-https/

What's the solution?

Camo is all about making insecure assets look secure. This is an SSL image proxy to prevent mixed content warnings on secure pages served from GitHub.

This project has been used by Github itself to secure external content.

A Ruby and a PHP clients are available. These library sign and encrypt URLs passed to camo to secure proxy usage.

Camo is pretty easy to install and run. The only issue is that you will get the trafic for these images and you bandwidth may suffer (but using Amazon Cloudfront on top of that may fill your needs)

If you find this article useful, or have another approach to cover mixed content when using external media, leave a comment.

Show Comments Thomas VIAL

But you may not know that the core DNA of Parrot is bluetooth, especially car connectivity and they're quite good in this domain, and they work with major car manufacturers.

A new hope

#oopsididitagain #parrot #mambo joined the family

Une photo publiée par Thomas (@tomav) le 11 Déc. 2016 à 7h45 PST

And it's Awesome, like PS4 paddle but heavier.

Parrot Mambo Drone

You will really have fun flying this drone.

But few things are still missing

a configuration option to disable stabilization. Doing a front-flip using a button is cool, but we'd like to do it manually after some time. I opened a feature request on Parrot Forums (french) in case you want to support.
a FPV cam/vtx! This may be an option in the future...

But the good new, is that you can easily do it yourself!

FPV Upgrade

Here are the steps I followed to add a FPV cam/vtx to the Parrot Mambo:

order the Eachine TX02 5.8G 40CH (~25€, weight is only 5g). Exists in 25/200/600mw
get 2 small bullet connectors from one of LEGO (yes you have to destroy one, I was not able to find them on the market)
solder the bullet connector to the red and black camera wires
get small LEGO bricks and use double-sided tape to place the camera on front
plug this on the front LEGO row, and then plug the bullet connectors into the last row (when looking to the drone from the rear, red wire on the left hole, and black on right)
configure the FPV channel on the video transmitter and on your receiver (goggles or screen)

You're done. Enjoy immersion flights with your Parrot Mambo FPV!

#parrot #mambo #fpv #parrotmods - cc @parrot_official #diy

Une photo publiée par Thomas (@tomav) le 8 Janv. 2017 à 4h52 PST

Notes

Note that this does not really affect the flight time, perhaps one minute.
Since I wrote this article, I found the BoosterDrones Eye FPV Mambo which seems to be a good alternative. That said, the 3d printed part seems pretty cheap.
UPDATE: in september 2017, parrot released a FPV version of his Mambo mini drone, available on its official website.

Show Comments Thomas VIAL

When I wanted to get headtracking with my Skyzone SKY-01, I thought it would be as easy as plug & play. But it's not.

I found a lot of partial information over the internet, and wanted to share with a more complete version.

The configuration has to be done:

on the Skyzone Goggles AND
on your Futaba transmitter

Note that I'm using the following setup on my TBS Discovery:

DJI Naza-m V2
Zenmuse H3-2D with GoPro Hero4 Silver (no pan, only tilt)

Skyzone configuration

We begin with the goggles. By default, they use channel 5 for pan and channel 6 for tilt.

To change this setting:

Press and Hold Button "TRACK", then connect power to enter Head Tracker Setup Menu (Release as soon as beep). Head Tracker beeps indicating the current PPM Channel. See details below.
Short Press "TRACK" Button to select different PPM Channels

Here are the Beep PPM Channel:

1 short beep Pan CH5, Tilt CH6 (Factory default)
2 short beep Pan CH5, Tilt CH7
3 short beep Pan CH5, Tilt CH8
4 short beep Pan CH6, Tilt CH7
5 short beep Pan CH6, Tilt CH8
6 short beep Pan CH7, Tilt CH8

In my case, I wanted to use channel 8, so 5 and 6 beeps are both valid options.
You can now unplugged the power cable.

Your goggles are now configured!

Futaba configuration

This was the tricky part for me. But now I can explain you how to do.

Trainer

Long Press on +
Go to third screen
Select TRAINER
TRAINER master must be set to OFF
Every channel can be turned OFF, except channel 8:AU2, which needs to be set to FNC. It will be used to the Skyzone tilt.

Exit with END.

P.MIX1-6

Now go to P.MIX1-6 and:

Create a new mix on the first slot
Set RATEL and H to -100%
MASTER to AU2 (we take the tilt channel 8)
SLAVE to GER (we route it to the GER, channel 5)
SW to SwH (it is the Trainer Switch of the Futaba T8J)
POSI to DOWN (when switch will be down, headtracking will be enabled)

Exit with END, twice.

Tests

To enable your headtracker, you have to push the H switch. This switch cannot be blocked in the active position without a trick (see bellow).

When you active this switch, you can move your head up and down and your gimbal will follow.

Note that you have a TRACK button on your goggles. It allows you to reset the center position with a short press.

Show Comments Thomas VIAL

If you work in IT, you probably want to generate UML diagrams.
There are a lot of way to do that, but some may require proprietary softwares.

I had a look to some of them, and chose to explain the easiest ways I found using Open Source librairies (if you're a minimum techie)

The recommended tools are:

Scruffy, used on yUML.me online service
PlantUML, used by Mediawiki and others softwares

They won't fit the same usage / needs, so you should have an idea of what you need :-)

Scruffy

I discovered yUML.me mid-2014 when I started to work with Neo4j.
It's an amazing online tool, really easy to use for simple graphs.

Scruffy is the library used behind yUML.me, and is available for download/fork on Github.

But Scruffy:

is was hard to install because of dependencies
won't fit for complex graphs

I sent a Pull Request to explain of to install Scruffy under Mac OSX and here the detailed version:

install Homebrew
install graphviz and plotutils

brew install graphviz plotutils
brew install imagemagick --with-librsvg
if you haven't pip yet

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py sudo python get-pip.py
install scuffy and image (PIL replacement)

sudo pip install image scruffy

You can now use Scruffy, here's a basic example:

suml --png --font-family Purisa --scruffy "[Node A]->[Node B],[Node B]->[Node C],[Group [Node A][Node B]]" > test.png

Will generate:

PlantUML

Their website is really oldschool... yes. But this tool allows you to generate complex and real <uml> diagrams.

I personally use SublimeText as text editor / IDE, and Jayson Vantuyl created a plugin to generate you diagrams directly from this IDE.

The install guide available on Github is clear if you use SublimeText. Sorry, but I won't cover other IDE here, but PlantUML provides useful links.

Here is an activity diagram example:

@startuml
(*) --> if "Some Test" then
  -->[true] "activity 1"
  if "" then
    -> "activity 3" as a3
  else
    if "Other test" then
      -left-> "activity 5"
    else
      --> "activity 6"
    endif
  endif
else
  ->[false] "activity 2"      
endif
a3 --> if "last test" then
  --> "activity 7"
else
  -> "activity 8"
endif
@enduml

(Looks like basic code, isn't it?)

Will generate:

There are many kinds of diagrams that can be generated with PlanUML.

Show Comments Thomas VIAL

On my docker mail server, I experienced the following problem connecting to my IMAP server:

# Telnet authentication
$ telnet 192.168.59.103 143
Trying 192.168.59.103...
Connected to 192.168.59.103.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION STARTTLS] Courier-IMAP ready. Copyright 1998-2011 Double Precision, Inc.  See COPYING for distribution information.
a1 LOGIN user@domain.tld mypassword
* OK [ALERT] Filesystem notification initialization error -- contact your mail administrator (check for configuration errors with the FAM/Gamin library)
a1 OK LOGIN Ok.

Use gamin instead of fam

This is what is said about gamin on the Ubuntu website:

libgamin0
  Client library for the gamin file and directory monitoring system
or libfam0
  Client library to control the FAM daemon also a virtual package provided by libgamin0

I moved from fam to gamin:

apt-get install gamin

But the error moved from client side to server side.

imapd: Failed to connect to socket /tmp/fam--

I read a lot of posts over the Internet and many problems have been resolved installing gamin.
So I supposed that I had another problem.

So, especially if you are a docker user, read the next part.

Use a "real" unix user

In my postfix configuration, I forced the ownership of my mail data like this:

# Mail directory
virtual_mailbox_base = /var/mail
virtual_mailbox_domains = /etc/postfix/vhost
virtual_mailbox_maps = hash:/etc/postfix/vmailbox
virtual_alias_maps = hash:/etc/postfix/virtual
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000

The "problem" is that I did not have a unix user with uid 5000.
Without a real user, the gam_server daemon won't start.

I added a specific unix user with the appropriate uid and everything went OK, client and server side.

The short version, to summarize

If you experience one of these errors:

# Client Side, visible when trying to authenticate on the IMAP server using telnet
Filesystem notification initialization error -- contact your mail administrator (check for configuration errors with the FAM/Gamin library)

# Server Side, usually in /var/log/mail.log
imapd: Failed to connect to socket /tmp/fam--

Here is what you need to do:

Install gamin instead of fam,
Verify that your files are owned by an existing / real unix user, otherwise, gam_server won't start