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Cleanup GPIO page and add a dedicated LED page.

This commit is contained in:
Gauthier Provost 2018-10-03 17:12:41 +08:00
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docs/gpio.md
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## User Accessible GPIOs (J12)
Helios4 provide 12 GPIOs on J12 header that are free to use for user application. This header connected to 16-bit IO Expander [PCA9655E](http://www.onsemi.com/PowerSolutions/product.do?id=PCA9655E) using I2C bus 0.
Helios4 provides 12 GPIOs on header J12 which can be used for user application. Those GPIOs are provided via an 16-bit IO Expander [PCA9655E](http://www.onsemi.com/PowerSolutions/product.do?id=PCA9655E) connected to I2C bus 0.
![J12 Pinout](/img/hardware/gpio_pinout_j12.png)
![J12 Pinout](/img/gpio/gpio_pinout_j12.png)
| Pin | GPIO number | Remarks |
### Pinout Table
| Pin | Port | Remarks |
|------------|----------|---------|
| 1 | - | 3.3V supply |
| 2 | IO0_2 | |
@ -23,53 +25,51 @@ Helios4 provide 12 GPIOs on J12 header that are free to use for user application
| 14 | - | GND |
!!! warning
**IO0_0**, **IO0_1**, **IO0_5**, and **IO0_6** are reserved for system use. It is not advisable to access the I2C IO expander directly using I2C.
## LED Expansion (J18)
Helios4 board was designed to either use the on-board LEDs or use custom expansion panel (not-available). To use the header insure to switch to OFF the DIP switch SW2.
![Dipswitch LED](/img/hardware/dipswitch_led_off.png)
- - -
![J18 Pinout](/img/hardware/gpio_pinout_j18.png)
| Pin | LED number | Remarks |
|------------|----------|---------|
| 1 | - | 3.3V supply |
| 2 | - | Not connected |
| 3 | LED1 | Heartbeat LED |
| 4 | LED2 | System Fault LED |
| 5 | LED3 | SATA port 1 LED |
| 6 | LED4 | SATA port 2 LED |
| 7 | LED5 | SATA port 3 LED |
| 8 | LED6 | SATA port 4 LED |
| 9 | LED7 | USB activity LED |
| 10 | - | GND |
Ports **IO0_0**, **IO0_1**, **IO0_5**, and **IO0_6** are reserved for system use.
!!! important
It is not advisable to access the I2C IO Expander directly using I2C utilities.
## Accessing GPIOs under Linux
If the kernel support debugfs (*CONFIG_DEBUG_FS=y*), list of GPIOs can be accessed using
If the kernel supports debugfs (*CONFIG_DEBUG_FS=y*), list of GPIOs can be retrieved with the following command
`sudo cat /sys/kernel/debug/gpio`
```bash
sudo cat /sys/kernel/debug/gpio
```
and look for
Look for the **gpiochip2: GPIOs XXX-YYY** section, whereas **XXX** is first GPIO number and **YYY** is last GPIO number of IO expander.
`gpiochip2: GPIOs XXX-YYY, parent: i2c/0-0020, pca9555, can sleep:`
whereas **XXX** is first GPIO number and **YYY** is last GPIO number of IO expander.
- - -
```
gpiochip2: GPIOs 496-511, parent: i2c/0-0020, pca9555, can sleep:
gpio-496 ( |board-rev-0 ) in lo
gpio-497 ( |board-rev-1 ) in lo
gpio-498 ( |(null) ) out hi
gpio-499 ( |(null) ) in hi
gpio-500 ( |(null) ) in hi
gpio-501 ( |usb-overcurrent-stat) in hi
gpio-502 ( |USB-PWR ) out hi
gpio-503 ( |(null) ) in hi
gpio-504 ( |(null) ) in hi
gpio-505 ( |(null) ) in hi
gpio-506 ( |(null) ) in hi
gpio-507 ( |(null) ) in hi
gpio-508 ( |(null) ) in hi
gpio-509 ( |(null) ) in hi
gpio-510 ( |(null) ) in hi
gpio-511 ( |(null) ) in hi
```
Another way to get first GPIO number of the IO expander
`cat /sys/bus/i2c/devices/0-0020/gpio/gpiochip*/base`
```
cat /sys/bus/i2c/devices/0-0020/gpio/gpiochip*/base
```
- - -
Therefore the mapping between header J12 Pins and Sysfs GPIO numbers will be as described in the following table
** J12 assigned GPIO number in sysfs **
### GPIO Table
| Pin | Sysfs GPIO number | Remarks |
|----|-----|---------|
@ -88,30 +88,42 @@ Another way to get first GPIO number of the IO expander
| 13 | 511 | |
| 14 | - | GND |
!!! info
The GPIO number listed on the table most likely would not changed between kernel version.
!!! note
The mapping table is unlikely to change between Kernel version.
Declare GPIO number to be use.
### GPIO Control
`echo N | sudo tee -a /sys/class/gpio/export`
**1.** Export the GPIO number you want to use
Set the direction, "out" as output and "in" as "input".
```
echo N | sudo tee -a /sys/class/gpio/export
```
`echo DIRECTION | sudo tee -a /sys/class/gpio/gpioN/direction`
**2.** Set the direction, "out" for Output or "in" for Input
To read current GPIO input
```
echo DIRECTION | sudo tee -a /sys/class/gpio/gpioN/direction
```
`cat /sys/class/gpio/gpioN/value`
**3.** Now you can read or change the GPIO value
Write 0 or 1 to GPIO
To read GPIO value
`echo VALUE | sudo tee -a /sys/class/gpio/gpioN/value`
```
cat /sys/class/gpio/gpioN/value
```
To change GPIO value (only if GPIO set as Output)
```
echo VALUE | sudo tee -a /sys/class/gpio/gpioN/value
```
!!! notes
Pay attention to the path, /sys/class/gpio/gpio**N**/
Pay attention to the path, /sys/class/gpio/gpio**N**/ where **N** is the GPIO number.
### Example
#### Example
Set IO1_7 (pin 13) output as high

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## Expansion Panel (J18)
Helios4 board was designed to either use the on-board LEDs or use a custom expansion panel (not-available). If you wish to use the header insure to switch to OFF the DIP switch SW2.
![Dipswitch LED](/img/led/dipswitch_led_off.png)
### Pinout Table
![J18 Pinout](/img/led/gpio_pinout_j18.png)
| Pin | LED number | Remarks |
|------------|----------|---------|
| 1 | - | 3.3V supply |
| 2 | - | Not connected |
| 3 | LED1 | Heartbeat LED |
| 4 | LED2 | System Fault LED |
| 5 | LED3 | SATA port 1 LED |
| 6 | LED4 | SATA port 2 LED |
| 7 | LED5 | SATA port 3 LED |
| 8 | LED6 | SATA port 4 LED |
| 9 | LED7 | USB activity LED |
| 10 | - | GND |

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mkdocs.yml
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@ -61,6 +61,7 @@ pages:
- Hardware:
- Overview : 'hardware.md'
- GPIO : 'gpio.md'
- LED : 'led.md'
- PWM (Fan) : 'pwm.md'
- I2C (OLED) : 'i2c.md'
- SPI (NOR Flash) : 'spi.md'