Using a FTDI adapter as an IR emitter

Este artigo é a parte 1 de 5 da série  Using a FTDI adapter as an IR

[Crazy intro, just talking to myself]

20 years ago, when I first heard about linux, it didn’t attract me much… spending lots ot time compiling the kernel or the drivers on a 486 seemed so crazy, I wasn’t geeky enough for that. Catched the linux train many years later with Ubuntu 6.04 or 6.10 when almost everything “just worked” and a few google searchs were enough when something didn’t work as expected.

And this week I found myself compiling libftdi and LIRC on a LEGO Mindstorms EV3! Gosh… what happened to me?

[end of crazy intro, start of long and probably boring intro]

Two years ago I found a way to use the soundcard of my laptop as a remote controller for my LEGO motors, thanks to LIRC. It worked OK and it even worked with my Android 4.x phone but never worked properly with ev3dev (and, some months later, I found that it also didn’t worked with my Android 5.x phone) and like most everything else I never really gave him a good use.

Last week someone asked at eurobricks forum how to use a HiTech IR controller with EV3. I also found a way to use it with ev3dev (picking up other people work) and once again never really giving it a good use. Hey, but somebody in the forum said it had tried my code! Thats amazing!

So I returned to LIRC and soundcard, decided to update my own howto. LIRC had evolved a bit in last two years and while reading some docs I found that LIRC also supports FTDI adapters. In fact, its extremely easy to make a USB IR emmiter with just a FTDI adapter and an IR LED, not even a resistor is needed!

I already had a few FTDI cables and adapters but they all use the FT232R model and for reliable timings a FT230X is needed. But my “local” supplier had a Sparkfun Beefy 3 that used FT231X, it’s not the FT230X but it seemed similar enough so I gave it a try… and it works!

[end of long boring intro]

So we need a recent version of LIRC that implements ftdix driver. Ubuntu and Debian jessie (so ev3dev also) only have 0.9.0… We need to download the source code directly from LIRC and compile ourselves. I downloaded the last version available, 0.9.4d.

For LIRC to compile the ftdix driver we also need libftdi. Ubuntu and Debian have it but I also compiled it from source – not sure why but at least for ev3dev just installing Debian libftdi packages is not enough and it seems that just compilling libftdi is also not enough, I had to do both.

My EV3 is running ev3dev snaphot 2017-02-06. Two days later there’s already a new snaphot but I only updated with apt:

sudo apt update
sudo apt upgrade
sudo apt dist-upgrade

After reboot my Ev3 is running kernel 4.4.47:

Linux ev3dev 4.4.47-19-ev3dev-ev3 #1 PREEMPT Wed Feb 8 14:15:28 CST 2017 armv5tejl GNU/Linux

First we install all dependencies needed for both LIRC and libftdi:

sudo apt install libftdi-dev build-essential pkg-config xsltproc libusb-1.0 cmake libboost-all-dev

This takes about an hour, lots of packages (mostly related to libboost)

Before spending lots of time compiling it is better to test if out FTDI adapter works as expected so we can download this “hello ftdi” example:

I saved it as “hello-ftdi.c”.

Now we insert our FTDI adapter and look for it at the end of dmesg:

[47800.964059] usb 1-1.2: new full-speed USB device number 8 using ohci
[47801.111337] usb 1-1.2: New USB device found, idVendor=0403, idProduct=6015
[47801.111424] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[47801.111472] usb 1-1.2: Product: FT231X USB UART
[47801.111515] usb 1-1.2: Manufacturer: FTDI
[47801.111553] usb 1-1.2: SerialNumber: DN01DR29
[47801.306754] usbcore: registered new interface driver usbserial
[47801.414060] usbcore: registered new interface driver ftdi_sio
[47801.423075] usbserial: USB Serial support registered for FTDI USB Serial Device
[47801.437994] ftdi_sio 1-1.2:1.0: FTDI USB Serial Device converter detected
[47801.449290] usb 1-1.2: Detected FT-X
[47801.454135] usb 1-1.2: FTDI USB Serial Device converter now attached to ttyUSB0

We see that it is detected and we take note of the idVendor and idProduct values:

idVendor=0403, idProduct=6015

For later use we also take note of its Serial Number:


Now we edit the “hello-ftdi.c” program and update the idVendor and idProduct.

/* hello-ftdi.c: flash LED connected between CTS and GND.
   This example uses the libftdi API.
   Minimal error checking; written for brevity, not durability. */

#include <stdio.h>
#include <ftdi.h>

#define LED 0x08  /* CTS  (brown wire on FTDI cable) */

int main()
    unsigned char c = 0;
    struct ftdi_context ftdic;

    /* Initialize context for subsequent function calls */

    /* Open FTDI device based on FT232R vendor & product IDs */
    if(ftdi_usb_open(&ftdic, 0x0403, 0x6015) < 0) {
        puts("Can't open device");
        return 1;

    /* Enable bitbang mode with a single output line */
    ftdi_enable_bitbang(&ftdic, LED);

    /* Endless loop: invert LED state, write output, pause 1 second */
    for(;;) {
        c ^= LED;
        ftdi_write_data(&ftdic, &c, 1);

Then we compile our “hello-ftdi” test program:

gcc hello-ftdi.c -lftdi -o hello-ftdi
hello-ftdi.c: In function 'main':
hello-ftdi.c:25:5: warning: 'ftdi_enable_bitbang' is deprecated (declared at /usr/include/ftdi.h:413) [-Wdeprecated-declarations]
     ftdi_enable_bitbang(&ftdic, LED);

We can ignore that warning, as long as we get a “hello-ftdi” binary file.

To run it we need root permissions:

sudo ./hello-ftdi

If we connect a common led between CTS (A) and GND (K) we will see it blink each second so we can replace it with a infrared LED (940 nm is better but 950 nm will also work). And yes, we don’t need to use a resistor.

If we check dmesg again, we notice that our test program disconnected the ttyUSB device, as required:

[15564.602213] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
[15564.602615] ftdi_sio 1-1.2:1.0: device disconnected

This post was to long for my web server so I broke in several.


Using a FTDI adapter as an IR emitter – 2

Este artigo é a parte 2 de 5 da série  Using a FTDI adapter as an IR

We should now compile LIRC  but as I said before I never got it working  without also compiling libftdi.

I downloaded and extracted ibftdi1-1.3 source code. Then:

cd  libftdi1-1.3
mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX="/usr" ../

If everything is OK, we see:

-- Building unit test
-- Configuring done
-- Generating done
-- Build files have been written to: /home/robot/libftdi1-1.3/build



If everything OK:

[100%] Built target test_libftdi1

And finally:

sudo make install



Using a FTDI adapter as an IR emitter – 3

Este artigo é a parte 3 de 5 da série  Using a FTDI adapter as an IR

Now back to where we extracted LIRC:

cd lirc-0.9.4d

If all conditions are satisfied we get this at the end:

checking for FTDI... no
checking for FTDI... yes
Summary of selected options:
prefix:                         /usr/local
sysconfdir:                     ${prefix}/etc
host:                           armv5tejl-unknown-linux-gnueabi
host_os:                        linux-gnueabi
forkpty:                        -lutil
usb_libs                        -lusb -lusb-1.0
lockdir:                        /var/lock/lockdev



We may now proceed with


and in a perfect world or at least with my Ubuntu it will build everything fine. But on my EV3 for two times I got this:

CDPATH="${ZSH_VERSION+.}:" && cd . && /bin/bash /home/robot/lirc-0.9.4d/missing aclocal-1.15 -I m4
/home/robot/lirc-0.9.4d/missing: line 81: aclocal-1.15: command not found
WARNING: 'aclocal-1.15' is missing on your system.
         You should only need it if you modified 'acinclude.m4' or
         '' or m4 files included by ''.
         The 'aclocal' program is part of the GNU Automake package:
         It also requires GNU Autoconf, GNU m4 and Perl in order to run:
Makefile:479: recipe for target 'aclocal.m4' failed
make: *** [aclocal.m4] Error 127

That’s strange because my Ubuntu doesn’t have autoconf installed.

I tried installing several packages but make always failed. After some googling I found a workaround. Is rather strange and honestly I don’t know why but it works:

sudo apt install automake m4 autoconf
autoreconf -i

This wil take a lot of time (at least half an hour) but after that the compiling process works as expected (almost an hour more):

sudo make install


Using a FTDI adapter as an IR emitter – 4

Este artigo é a parte 4 de 5 da série  Using a FTDI adapter as an IR

We finally have LIRC but if we run it now it will fail looking for “” so we need to configure ev3dev to look for it in the right place:

sudo nano /etc/

  include /usr/local/lib

sudo ldconfig

We could also build LIRC with proper prefix options in order to prevent this last step but I’m lazy and this also helps when searching the web for common problems.

We also need to create a folder for LIRC to place a pid file:

sudo mkdir /var/run/lirc

and at least one remote control configuration file that tells LIRC how to talk with the Power Fucntions IR Receiver. So after two years I’m back to Connor Cary’s GitHub and find that he now has 3 configuration files available:

  • Combo_Direct
  • Combo_PWM
  • Single_Output

The last one was contributed by Diomidis Spinellis, the author of a very nice post “Replace Lego’s $190 Intelligent Brick with MIT’s Scratch and a $40 Raspberry Pi” I read a few months ago – what a small world we live 🙂

We should save these 3 files with a “.conf” extension under the folder


There is already a “devinput.lircd.conf” file there but it only works with LIRC default device so we should rename it:

sudo mv /usr/local/etc/lirc/lircd.conf.d/devinput.lircd.conf /usr/local/etc/lirc/lircd.conf.d/devinput.lircd.dist

And that’s it, next post we’ll finally start LIRC!

Using a FTDI adapter as an IR emitter – 5

Este artigo é a parte 5 de 5 da série  Using a FTDI adapter as an IR
sudo lircd -dserial=DN01DR29,output=3 -Hftdix

We gave lircd 3 parameters:

  • “DN01DR29” is the serial number of my FTDI adapter reported by dmesg
  • “output=3″ is the CTS pin we use to control the LED (in the ‘hello-ftdi.c” test we see LED defined as 0x08, that’s because LIRC ftdix drivers calculates the pin by left-shifting, so 2<<3 = 2³ = 8)
  • “ftdix” is the driver to use

We should check if lircd is running. In Ubuntu it writes several messages at “/var/log/messages” but this log doesn’t exist in ev3dev so

pgrep lircd

E also see in dmesg that the ttyUSB device was disconnected by libftdi:

[47897.512814] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
[47897.513393] ftdi_sio 1-1.2:1.0: device disconnected

We now use ‘irsend’ to check for available transmitter:

sudo irsend -d/var/run/lirc/lircd LIST "" ""


We can also list all commands avaible for a particular transmitter:

sudo irsend -d/var/run/lirc/lircd LIST LEGO_Combo_Direct ""

000000000000010e FLOAT_FLOAT
000000000000011f FLOAT_FORWARD
000000000000012c FLOAT_BACKWARD
000000000000013d FLOAT_BRAKE
000000000000014a FORWARD_FLOAT
000000000000015b FORWARD_FORWARD
0000000000000168 FORWARD_BACKWARD
0000000000000179 FORWARD_BRAKE
0000000000000186 BACKWARD_FLOAT
0000000000000197 BACKWARD_FORWARD
00000000000001a4 BACKWARD_BACKWARD
00000000000001b5 BACKWARD_BRAKE
00000000000001c2 BRAKE_FLOAT
00000000000001d3 BRAKE_FORWARD
00000000000001e0 BRAKE_BACKWARD
00000000000001f1 BRAKE_BRAKE

For first test we’ll just use “FORWARD_FORWARD” command (move both motors, “Red” and “Blue”, forward):

sudo irsend -d /var/run/lirc/lircd SEND_ONCE LEGO_Combo_Direct FORWARD_FORWARD

And our motor do spin!

So, after such a big post, whats the point?

Well, since LIRC can handle several transmitter and for ftdix it uses the serial number of the FTDI adapter to identify each transmitter… we can have as much transmitters as we want as long as our system can handle it. On a laptop or a Raspberry Pi 3 that’s probably 127 (the max number of USB devices we can have). Most probably the Ev3 will gasp will all that USB devices but at least two I know it can handle:

Will show how in a fourth post, later on.