Originally made by Texas Instruments (2003).
In 2007, TI sold its DSL business to Infineon. The part number on the SoCs changed the prefix TNETD to PSB
In 2009, Infineon spins off its wireline division to Lantiq. On November 6, 2009, Lantiq annouced that it became a standalone company
The Architecture is based on a standard MIPS32 Instruction Set, sharing features with the R4600 microprocessor. It can operate in both little and big endian modes. Almost all brands ship their devices configured in little Endian but Zyxel using Big Endian.
adam2: The bootloader commonly used in AR7, with some limitations.
PSPBoot: an evolution of ADAM2, used in the most modern devices
Bootbase: bootloader used by Zyxel in AR7, working in Big endian mode
EVA: not very common in AR7, based on Adam2
In OpenWrt the AR7 GPIOs can be accessed by using the char device /dev/gpio, but first you may need to make them available
mkdir /dev/gpio for i in `seq 0 31`; do mknod /dev/gpio/gpio$i c 254 $i; done
Now you can control GPIOs using the echo command
echo e > /dev/gpio/gpioX
echo d > /dev/gpio/gpioX
echo o > /dev/gpio/gpioX
echo i > /dev/gpio/gpioX
echo 1 > /dev/gpio/gpioX
echo 0 > /dev/gpio/gpioX
Example, use GPIO5 as an output and put it on high state:
echo e > /dev/gpio/gpio5
echo o > /dev/gpio/gpio5
echo 1 > /dev/gpio/gpio5
With latest OpenWrt versions should be possible to control GPIOs by using the /sys/class/gpio/ interface, but it doesn's seeem to be enabled in the kernel. Therefore building your own firmware with GPIO_SYSFS enabled is required.