FHEM und FritzBox 7240

Instructions and recommendations for running Fhem on a FritzBox 7240.

CUL

flash CUL_V3.hex (from Atmel page)
attach CUL to Fritz!Box (with a USB Hub to have USB-Memory stick and CUL running at the same time)

Note: to check if CUL works, in FritzBox settings enable USB-Fernanschluss. Now it gets recognized as CUL868. Remember to disable it again. The CUL should be recognized as Es handelt sich um ein nicht unterstütztes USB-Gerät. This is OK!

Fritz!Box 7240

Update Fritz!Box to Firmware-Version >= 73.05.05
download Fhem
unzip and store at root of your USB-Memory stick in the folder "fhem" (this will be /var/InternerSpeicher/<yourUsbStickName>/fhem/ on you Fritz!Box lateron.
in this folder, adapt the file "startfhem" if you use more than one storage device (e.g. USB memory stick and 1&1 Online Speicher") with hardcoded destination folder for your fhem path:
home=/var/InternerSpeicher/SanDisk-Cruzer-01/fhem
Alternatively, disable "1&1 Online Speicher" and use USB memory stick only. This way you don't have to adapt startfhem.
to use telnet, it needs to be enabled via phone by dialing #96*7*. To login, use the same password as for Fritz!Box webfrontend. Now you can edit all of your files using vi in telnet.
Now define your "fhem.cfg" to match your configuration, e.g. starting with your housecode:
define myCUL CUL /dev/ttyACM0 1234

...
finally start fhem in telnet:
/var/InternerSpeicher/SanDisk-Cruzer-01/fhem/startfhem
or use autostart => see [#Autostart_fhem #Autostart fhem]

Open issues

Daily resets with big log files

After 1 week running perfectly I was seeing regular/daily resets. The problem in my setting is that I am using several FS20-STR. These devices send every 2-3 minutes off-for-timer or on-for-timers signals. These events get logged in the monthly log file. After this log was bigger then 1MB I have seen these resets. After I emptied/deleted the file the box is running stable again.

After looking into the details, it seems that the 7240 gets a memory problem when log files get bigger than ~800KB. I changed the logging from monthly files to weekly files (using ./log/fhem-%Y-%m-%V.log). This way, files should no longer get that big. Since then, 7240 runs stable without any problems.