Phytec phyBoard Wega AM335x, Инструкция по применению

Страница: 125 / 130

Advanced Information
©
PHYTEC Messtechnik GmbH 2014 L-792e_1
109
Now you can read the values with
cat GPIOno /value
Example:
cd /sys/class/gpio
echo 106 > export
cat gpio106/value
will read the value at pin 33 (GPIO3_10) at the expansion connector. To get the next
values, just retype
cat gpio106/value
In order to use the GPIOs not used by the LED driver as output you can change the direction
after you have requested the GPIO by entering
echo out > GPIOno /direction
Now you can write to the GPIO with
echo 1 > GPIOno /value
and
echo 0 > GPIOno /value
Example:
cd /sys/class/gpio
echo 63 > export
echo out > 63/direction
echo 1 > 63/value
will result in a high level at pin 44 (GPIO1_31) at the expansion connector.
A different procedure is necessary for the GPIOs already requested by the LED driver
(GPIO2_18, GPIO2_19 and GPIO3_9). For setting and resetting these LED outputs on the
expansion connector switch to the appropriate directory listed in the following table:
Pin # Signal Name Path
31 GPIO3_9
/sys/class/leds/user_led_green
35 GPIO2_18 /sys/class/leds/user_led_red
36 GPIO2_19 /sys/class/leds/user_led_yellow
Table 23: GPO Pins and Device Path
and enter:
echo 255 > brightness
for a high level at the pin, and
echo 0 > brightness
for a low level at the pin