Difference between revisions of "IoTGateway/BSP/Android/Gettingstarted/How to use GPIO"
From ESS-WIKI
| Line 104: | Line 104: | ||
Export GPIO 27 | Export GPIO 27 | ||
| − | <pre># echo 27 /sys/class/gpio/export | + | <pre># echo 27 > /sys/class/gpio/export |
</pre> | </pre> | ||
Set GPIO direction to in/out | Set GPIO direction to in/out | ||
| − | <pre># echo " | + | <pre># echo "out" > /sys/class/gpio/gpio27/direction |
</pre> | </pre> | ||
Set GPIO value 0/1 if GPIO pin define is output | Set GPIO value 0/1 if GPIO pin define is output | ||
<pre># echo 1 > /sys/class/gpio/gpio27/value | <pre># echo 1 > /sys/class/gpio/gpio27/value | ||
| − | |||
| − | |||
| − | |||
| − | |||
</pre> | </pre> | ||
| Line 131: | Line 127: | ||
Unexport GPIO 27 | Unexport GPIO 27 | ||
| − | <pre># echo 27 /sys/class/gpio/unexport | + | <pre># echo 27 > /sys/class/gpio/unexport |
</pre> | </pre> | ||
Latest revision as of 11:44, 19 June 2017
Configuration/Test
Configuration
The i.MX 6 bank/bit notation for GPIOs must be formed as "GPIO<GPIO_bank>_IO<gpio_bit>"
The numeric value of GPIO is calculated as follows:
32 x (gpio_bank- 1) + gpio_bit
E.g. GPIO2_IO04 becomes 36
ROM-3421
| GPIO Number | GPIO formed | Numeric Representation |
| GPIO0 | GPIO_1 | 1 |
| GPIO1 |
GPIO2_IO2 | 34 |
| GPIO2 |
GPIO2_IO3 |
35 |
| GPIO3 |
GPIO_3 | 3 |
| GPIO4 |
GPIO7_IO12 |
204 |
| GPIO5 |
GPIO7_IO13 |
205 |
| GPIO6 |
GPIO7_IO6 |
198 |
| GPIO7 |
GPIO6_IO08 |
168 |
| GPIO8 |
GPIO2_IO06 |
38 |
ROM7420
| GPIO Number | GPIO formed | Numeric Representation |
| GPIO0 | GPIO6_IO11 | 171 |
| GPIO1 |
GPIO6_IO14 | 174 |
| GPIO2 |
GPIO6_IO15 |
175 |
| GPIO3 |
GPIO6_IO16 | 176 |
| GPIO4 |
GPIO2_IO25 |
57 |
| GPIO5 |
GPIO2_IO23 |
55 |
| GPIO6 |
GPIO2_IO24 |
56 |
| GPIO7 |
GPIO5_IO02 |
130 |
Test
Export GPIO then you can use control GPIO from userr space through sysfs
Export GPIO 27
# echo 27 > /sys/class/gpio/export
Set GPIO direction to in/out
# echo "out" > /sys/class/gpio/gpio27/direction
Set GPIO value 0/1 if GPIO pin define is output
# echo 1 > /sys/class/gpio/gpio27/value
Used as IRQ signal
Note:You have to configure GPIO to input
# echo "rising" > /sys/class/gpio/gpio27/edge
- rising: Trigger on rising edge
- falling: Trigger on falling edge
- both: Trigger on both edges
- none: Disable interrupt on both edges
Unexport GPIO 27
# echo 27 > /sys/class/gpio/unexport
Test
GPIO 27 and GPIO 29 are taken as an example:
- Connect GPIO 27 and GPIO 29
- Export GPIO 27 and GPIO 29
# echo 27 /sys/class/gpio/export # echo 29 /sys/class/gpio/export
- Set GPIO 27 to output
# echo "out" > /sys/class/gpio/gpio27/direction
- Set GPIO 29 to input
# echo "in" > /sys/class/gpio/gpio29/direction
- Change GPIO 27 to 1 and read GPIO 29 value
# echo 1 > /sys/class/gpio/gpio27/value # cat /sys/class/gpio/gpio29/value 1
- Change GPIO 27 to 0 and read GPIO 29 value
# echo 0 > /sys/class/gpio/gpio27/value # cat /sys/class/gpio/gpio29/value 0