getting rfid rc522 to work with raspberry pi 2 Image from https://raspberrypi.stackexchange.com/questions/37021/.

Running Overclocked Raspberry Pi 2 B With FreeBSD Overclocking options: arm=1000MHz, core=500MHz, sdram=500MHz, overvolt=2

1 echo 'kernel.panic = 10' >> /etc/sysctl.conf 1 2 3 // kern.coredump=0 // kern.corefile=/dev/null // background_fsck="NO" # on zfs ;)

SoC (Broadcom BCM2835 ARMv6) thermal range is up to +85 °C. Orginal /boot/config.txt: 1 2 3 4 5 disable_commandline_tags=1 gpu_mem=32 device_tree=rpi.dtb device_tree_address=0x100 kernel=uboot.img My additional options (stable system): 1 2 3 4 5 6 7 8 9 10 11 12 arm_freq=900 arm_freq_min=700 gpu_freq=250 gpu_freq_min=250 core_freq=450 core_freq_min=250 sdram_freq=500 sdram_freq_min=400 over_voltage=0 over_voltage_min=0 initial_turbo=15 temp_limit=75 Based on http://elinux.org/RPiconfig#Overclocking_options.

1 echo 'hw.bcm2835.sdhci.hs="0"' >> /boot/loader.conf

The ESP8266 is a low price SoC with WLAN / UART / SPI interface (ardoino alternative). https://www.mikrocontroller.net/articles/ESP8266