Kontron KTT20-pITX - Manual (Page 33)

KTD-S0045-D Page 29 U-Boot Compilation
KTT20/pITX Software Guide
8.1 Hardware Components Compatibility
Between the KTT20/pITX and the 'Harmony' evaluation board there are following conformities/differences:
Component KTT20/pITX vs. 'Harmony' Evalboard
SDRAM Compatible
NAND Compatible
SPI TM Flash Compatible
PMU Compatible
LAN Compatible
DVI ® DVI ® vs. HDMI ®
CRT Compatible
LVDS Compatible
USB Client Compatible
USB Nearly compatible
microSD TM (MMC) Compatible
Audio Compatible
PCI Express ® Compatible
I 2 C TM Not compatible
UARTs Not compatible
GPIOs Not compatible
Temperature Sensor Compatible
8.2 GPIO Declarations
The directory 'drivers/gpio' contains a module named 'tegra2_gpio.c'. It disposes of all needed routines to
declare a GPIO as input or output respectively to read or write a value. An overview:
int gpio_request // Configure as GPIO (only in older versions)
int gpio_direction_input // Set GPIO as input
int gpio_direction_output // Set GPIO as output
int gpio_get_value // Read input value
void gpio_set_value // Set output value
Example (symbolic names see 'arch/arm/include/asm/arch-tegra2/gpio.h'):
// gpio_request is a function from older U-Boot versions - possibly not necessary
ret = gpio_request (GPIO_PT1, NULL); // define GPIO33 as GPIO, also labeled T.01
if (ret) {
do something; // Error
}
gpio_direction_input (GPIO_PT1); // Set GPIO as input
ret = gpio_get_value (GPIO_PT1); // Read value, result is always Bit 0