15. Layer API GPIO -
USER SPACE USER SPACE USER SPACE
PROGRAM PROGRAM PROGRAM
I2C SPI GPIO
/DEV/I2C-0 /DEV/SPI-TEST /DEV/GPIO SYSFS
I2C API SPI GPIO API
AT91 MUXER LINUX KERNEL
CPU
16. Interfaccie
Driver kernel GPIO
https://dev.openwrt.org/browser/trunk/target/linux/generic-2.6/files/drivers/char/gpio_dev.c
Esempio di programma user-space gpio
https://dev.openwrt.org/browser/trunk/package/gpioctl/src/main.c
Driver SPI
http://lxr.linux.no/#linux+v2.6.32/drivers/spi/spidev.c
Esempio di programma user-space spi
http://lxr.linux.no/#linux+v2.6.32/Documentation/spi/spidev_test.c
Driver I2C
http://lxr.linux.no/#linux+v2.6.32/drivers/i2c/i2c-dev.c
Esempio di programma i2c userspace
http://netus.acmesystems.it/doku.php?id=tutorial:srf02
17. Esempio GPIO
echo 82 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio82/direction
echo 1 > /sys/class/gpio/gpio82/value
echo 0 > /sys/class/gpio/gpio82/value