You might have noticed that my site was down for maintenance on Wednesday, 2014-09-17. For better WordPress performance, I decided to migrate my blog to a brand-new Banana Pi server, featuring a Cortex-A7/ Allwinner A20 Dual-core CPU with Mali-400M2 GPU — that’s cheating — I know 😀.
It took me a couple of hours and some tinkering to move my WordPress installation including the MySQL database onto the new server. So here are my first impressions:
I’ve been a little reluctant to connect a DS18S20 temperature sensor to my RasPi, since there were rumors that the w1_gpio.ko kernel module exclusively requires a connection to GPIO #4, because of being hard coded. At least that’s what Lady Ada’s tutorial says about it and what one can read in several user forums. Unfortunately GPIO #4 was already occupied on my Pi. Therefore I searched through several Blogs for advice how to change the hard-coded GPIO in the kernel module. It turned out that I wasn’t the only one – so here’s the good news: In Raspbian Wheezy with Kernel 3.10.25+ it is possible to pass the desired GPIO in /boot/cmdline.txt to the kernel using the option:
bcm2708.w1_gpio_pin=<GPIO#>
To be able to read temperatures from the sensor, modprobe the wire, w1_gpio and w1_therm kernel modules. The temperature can be read from /sys/bus/w1/devices/<device_serial_number>/w1_slave.
I’m using the the sensor for outdoor temperature measurement. I soldered about 1 m wire to the sensor (TO92 housing), insulated the solder joints with heat shrink tube and embedded the sensor into an old metal ballpoint cap using epoxy glue.