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Re: [Paparazzi-devel] Problem with FTDI ground station

From: Nicolas Quendez
Subject: Re: [Paparazzi-devel] Problem with FTDI ground station
Date: Sun, 24 Aug 2014 08:45:02 -0300

Situation in progress..
I formatted my computer, and re-install everything. 
Now GCS is working when the AP is connected by wire to the ground station, good ! 

BUT : still no telemetry when replacing the wire by the two modems. 
Modem Configuration : both the same, except ground station in coordinator, AP in end device. Both in transparent mode (AT), 57600 br. I use xbee868.xml telemetry file. 

Situation : 
- On XCTU, I can see from the ground station modem that it receives informations from the AP as soon as I power on the AP. So there is communication between them. But, the communication seems odd to me : the ASCII transmitted is not looking like code, is it normal  ? 

Thanks again for your help
Best regards

Le 23 août 2014 à 14:00, David Conger <address@hidden> a écrit :

On Thu, Aug 21, 2014 at 1:19 PM, Nicolas Quendez
<address@hidden> wrote:

Thanks everybody for the help !
My answers  :

Is this a Virtual Machine or dedicated hardware?

Dedicated Lenovo T400 only for paparazzi, with Ubuntu (only).

Do you have anything else connected to USB?

No, except the autopilot when flashing the firmware, on the second USB...

As devices are found on startup (and after) they will be assigned a device
with a number in /dev. So the first USB serial device is going to be given
/dev/ttyUSB0. The second will become /dev/ttyUSB1 and so on. Your hard disk
and about everything is a device and located in there so do not create or
remove devices by editing or changing things in /dev/. Thankfully Linux
comes with most all the drivers you need so this probably isn't a problem
with a driver (.dll file in Windows). Usually it is the simplest thing
(broken wire, mismatched Tx to Rx, wrong device directive in the command
line for Data Link etc). Let's keep looking for a simple solution.

Let's also keep it simple. Let's not debug the XBee modems yet. Unplug the
XBee from the FTDIUtil as that will block the use of the cable to connect to
the Lisa/M over serial.

My debugging usually goes like:

1. Unplug the FTDIUtil
2. Make sure autopilot is powered off
3. In Paparazzi Center, click "Stop/Remove all Processes"
<order matters here so please follow these steps exactly>
4. Now plug the FTDUtil into USB to the Computer NOTE: Lisa/M powered off
and the cable unplugged from the Lisa/M
5. At a  terminal window type: dmesg ... verify in the output the FTDIUtil
appears as /dev/ttyUSB0 and « connected"

When typing dmesg  I do not see the term « connected » and I see ttyUSB0 but
not /dev/ttyUSB0 :

There are a lot of things written, and at the end :

[80975.226298] sd 4:0:0:0: [sdb] No Caching mode page found
[80975.226307] sd 4:0:0:0: [sdb] Assuming drive cache: write through
[80975.226315] sd 4:0:0:0: [sdb] Attached SCSI removable disk
[81002.332104] usb 6-2: new full-speed USB device number 3 using uhci_hcd
[81002.529142] usb 6-2: New USB device found, idVendor=0403, idProduct=6001
[81002.529151] usb 6-2: New USB device strings: Mfr=1, Product=2,
[81002.529159] usb 6-2: Product: FT232R USB UART
[81002.529166] usb 6-2: Manufacturer: FTDI
[81002.529173] usb 6-2: SerialNumber: A600eGeJ
[81002.536216] ftdi_sio 6-2:1.0: FTDI USB Serial Device converter detected
[81002.536290] usb 6-2: Detected FT232RL
[81002.536297] usb 6-2: Number of endpoints 2
[81002.536304] usb 6-2: Endpoint 1 MaxPacketSize 64
[81002.536311] usb 6-2: Endpoint 2 MaxPacketSize 64
[81002.536317] usb 6-2: Setting MaxPacketSize 64
[81002.538290] usb 6-2: FTDI USB Serial Device converter now attached to

I was going by memory. What you see is Linux finding the device and
setting it up. If you did ls -lh /dev/ttyUSB0 you would see the
device. This is good.

6. Now connect the Lisa/M with the 3 wire connector to the FTDIUtil
7. Now power the Lisa/M
8. Now in the Paparazzi Center set: Target = ap, Session = Flight
address@hidden, and click "Execute"

3 processes should be launched each with a command line shown in an area.
All 3 should show "Stop" if they are running for the button. If one says
"Redo" then that means it did not start successfully.

All the 3 processes are running smoothly. But GCS is empty with « waiting
for telemetry ».

This is a bit odd as the Data Link seems to me should fail if you did
not have rights (udev rules) setup, implying it is setup per the Wiki
instructions. Are you, or have you ever run the paparazzi software as
root? Maybe this is still a permissions issue. Isn't there an error
somewhere in the output in Paparazzi Center about connection denied or
refused or something?

There is a log of activity in Linux. For Ubuntu 13 it maybe
interesting to look at the contents of /var/log/syslog or
/var/log/auth.log (last lines should be the interesting parts).

What I have found is sometimes if the autopilot is powered and connected to
the FTDIUtil the linux system may consider the device busy and assign a new
device when the FTDI is connected like /dev/ttyUSB1. So the order of the
above will make sure (for me at least) that /dev/ttyUSB0 is used each time.

What is the output from the above?

About the XBee you have. Here is what I do.
1. Using the FTDIUtil plug in the GROUND modem and launch X-CTU
2. Add the XBee and verify it is set for:
a. 57,600 comm rate
b. Coordinator
c. either API or AT but be sure both have the same directive as to the use
of API or not using API

for the airborne one you setup the same settings except for one very
important difference. The airborne one is not a coordinator it is an
end-device/router. Granted I only work with the XBee Pro S1/S2 with mesh so
if your are using non mesh maybe there is no option for coordinator and

BTW: I have never seen the modems you show in the photo. Are they a new

These modems are the xbee 868 LP, that should be OK for Europe if I
understood well…

I see. I have no experience with the 868 being here in the US as I
have other options.
I will not be much help with that one. You should have peers in the EU
using them as I have seen their posts on the list before.

So for now, no new test with the Xbee. I focus on the FTDI direct link for

Also if the FTDIUtil works with the cable it does not guarantee the XBee
with wireless will work. They are separate problems. Just if you get the
cabled way to work you can then focus on the XBee as the next problem.

Hope this helps keep you going. Remember, it's almost always something
simple. Paparazzi has been working since 2003. It's flexibility will become
something you find very empowering down the road when this all starts to
makes sense. Once past the startup learning process you will have a much
better understanding how this all works and have more confidence with what
you are doing with it. Keep trying is the path to success here.

I have no doubt about that. I will perseverate. I have skills in
aerodynamics and flight mechanics, but new on linux and electronics…

Thanks again


On Thu, Jul 24, 2014 at 5:52 AM, Nicolas Quendez <address@hidden>

Hi everybody,

I just begin to manipulate Paparazzi hardware and software.

For now :
- I succeed in working with flight plan simulation
- I succeed in uploading software into my Lisa M AP
- I succeed into programming my Xbee modules with XCTU (windows) with the
PPZUAV FDTI utility board.

when I plug the FTDI board with xbee module (coordinator) by USB on my
ubuntu computer, I have the following error when starting a session :
Failure("Error opening modem serial device : fd < 0 (/dev/ttyUSB0) ») :

RUN '/home/nicolas/paparazzi/sw/ground_segment/tmtc/link -d /dev/ttyUSB0
-transport xbee -s 57600'
Failure("Error opening modem serial device : fd < 0 (/dev/ttyUSB0)")
Broadcasting on network, port 2010
Read Socket : Connection reset by peer
FAILED '/home/nicolas/paparazzi/sw/ground_segment/tmtc/link' with code 1

I have checked with dmesg that /dev/ttyUSB0 seems to be the good place for
the board.
I have added the current user  to the modems group as explained in the FAQ
I made the xbee module set as coordinator, with baud rate set to 57000
My Xbee is a 868 LP 80 K modem.

On the PPZUAV FTDI board the red led is ON.
The green led is ON (but not flashing).

Have you any idea of my mistake, or configuration that I did not do ? Are
there some drivers to install for the FTDI board, or a configuration to put
into the xml files ?

Thanks in advance
Best regards

Hardware :

XCTU configuration :


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