Archive for the ‘Linux’ Category.

FHEM: Home Automation remote display using small OLED and MQTT

I wanted to have a small display with some essential Home Automation data. So I buy an 1.3″ OLED display with I2C interface and started to look for some existing code for an ESP8266. The display should be feed using WiFi and be portable, so I can place it where needed.

I started with ESPeasy, as there is already support for multiple pages with text lines. Unfortunately the code is written to show sensor data of directly connected sensor only. No option to publish free text or data from a Home Automation system. The ESPeasy code will save the text to flash memory on every change when using the Web GUI. The flash memory would wear out after some month with my use case.

Finally I decided to start my own code. First I had to find out that the OLED display is not an SD1306 but a SH1106 one. Although some people state that these are more or less the same, the SD1306 libraries did not work for me. Then I found which works well for me.

Starting with SSD1306UiDemo.ino I added WiFi and MQTT libaries and code.

My code will show 6 lines of text on two frames (3 lines each). The frames will change every 5 seconds. The content of the text lines is published by a FHEM server. As there was no easy way to integrate the display using a MQTT_DEVICE definition in FHEM, I wrote my own perl mqttmsg sub function and used the FHEM notify definition to publish changes to the display.

a small video

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FHEM: serielle Devices über Netzwerk anschliessen

Zu Testzwecken brauche ich ab und an neben meinen Haupt FHEM System ein zweites FHEM System, zB auf meinem Netbook. Nun sind drei Devices (nanoCUL 433MHz, nanoCUL 868MHz und ein Jeelink) direkt am Hauptserver über USB (serial) angeschlossen. Wenn ich diese in einem Testsystem benötige, müsste ich die Geräte vom Hauptserver trennen. Wie praktisch wäre es, wenn ich diese USB Devices über das Netzwerk anbinden könnte, so wie dies über EspLink mit dem angschlossenen Arduino Nano mit SignalDuino Firmware möglich ist.

Nun zur Anbindung von seriellen Geräten an das Netzwerk gibt es für Linux ser2net. Leider ist die Original-Version nicht multi-Client tauglich und würde nur einem Client die Verbindung erlauben. Bei EspLink sind jedoch mehrere Clients möglich. Obwohl die meisten ser2net Quellen nur einen Client unterstützen, gibt es ein oder zwei Quellen, deren Implementierung mehrer Clients unterstützen.

Nachdem ich einen Quellcode von ser2net mit multi-Client Support geladen und nach geringen Modifikationen auch erfolgreich implementieren konnte, kann ich nun alle Geräte, die am Haupt FHEM Server angeschlossen sind auch über mein Netzwerk nutzen. Die Geräte mussten nur in der ser2net conf Datei mit verschiedenen Netzwerkports eingetragen werden:


In der fhem.cfg wurden die Geräte entsprechend umdefiniert:

#define nanoCUL433 CUL /dev/serial/by-id/usb-FTDI_FT232R_USB_UART_A9YDLRJV-if00-port0@38400 1234
define nanoCUL433 CUL 1234
#define nanoCUL868 CUL /dev/serial/by-id/usb-FTDI_FT232R_USB_UART_A94BBD91-if00-port0@38400 3421
define nanoCUL868 CUL 4321

Die original EspLink Anbindung des Arduino Nano mit SignalDuino Firmware:

define sduinoIP SIGNALduino

Mit diesen Änderungen kann ich diese USB Geräte nun auch über das Netzwerk benutzen.

Meine Abwandlung von ser2net findet sich auf Github.

Enigma2 OpenEmbedded Enhanced Movie Center Trashfolder CleanUp

We own a great VuPlus Solo2 Linux based Satelit Receiver. We record some series and films and then delete them. The deleted media files are not deleted directly when using EMC to view and delete. The media files are moved to a trash folder first and should be automatically deleted after x days. But that does not work for whatever reason.

Recently I checked the trash folders I found, as I wondered why the box’s hard disk is getting filled up. And I found many, many old ‘deleted’ files, that are not removed from the hard disk.

I decided to write my own script (/home/root/, yes, there is a typo ;-)) ) to finally remove ‘deleted’ files after 7 days. The script was then added to the root’s crontab.

# delete old files
# delete trash files older than 7 days
/usr/bin/find /mnt/hdd/movie_trash -type f -mtime +7 -delete
/usr/bin/find /mnt/hdd/movie/trashcan -type f -mtime +7 -delete
cd /mnt/hdd/movie_trash/
rm last_cleanup*
touch last_cleanup_$( date '+%Y-%m-%d_%H-%M-%S' )
cd /mnt/hdd/movie/trashcan/
rm last_cleanup*
touch last_cleanup_$( date '+%Y-%m-%d_%H-%M-%S' )

The script deletes all files at /mnt/hdd/movie_trash and /mnt/hdd/movie/trashcan with a modification date of 7 days before current day. Then it adds a file with a timestamp as name to let me know, that the script has worked at what time.
… and the crontab (/etc/cron/crontabs/root):

1 1 * * * /home/root/

This starts the script every day at 1pm.

That’s all, thank’s to the author of the find utility.

WICD does not reconnect after suspend: obtaining IP address

My Debian 8 Jessie installed Acer Aspire One netbook had problems reconnecting after suspend resume.

WICD showed obtaining IP address for a long time and finally gave up or so. Tried dhclient and dhcpcd, no change. Tried debug mode, which results in the netbook sometimes did not resume to the OS and I had to do a hard reset :-(. Disabled debug logging option in wicd.conf again. Could not live with hard resets.

Changed dhcp server from integrated one in router (tested with different models) to my Linux Debian SID server, no change.

I added the option nolink (for buggy interfaces, found in man dhcpcd and dhcp.conf and inspried by LinuxQuestions.Org) to /etc/dhcpcd.conf and now WICD reconnects fine and fast after setting dhcpcd as external DHCP Client. WICD is version 1.7.24.

Issue solved 🙂

UPDATE 31.8.2016:

Bad news: WICD still does not resolve DHCP address. I mostly have to Cancel the ‘Obtaining IP address…’ process and manually connect. Some times it connects on first time but some times on second or thrird attempt.

Now tested connman. But it behaves alsoe strange. After first install everything looked fine. But after reboot it stated no services available or other strange errors about no wifi and sh.. After some more tests I relaized that connman is not really integrated into Debian. Maybe it is good for ArchLinux? Fortunately I always got a connection using ifdown/ifup for wlan0.

Finally I switched to network-manager and network-manager-gnome. And that impressed me. It connects very, very fast. Hopefully that will be reliable. Suspend and resume also works fine without fiddeling in any conf files so far.

BTW: I am running two Cisco APs with same SSID/WPA2 passphrase, so the devices can roam (no AP controller, just the Cisco APs). Possibly that makes WICD nervous?