Difference between revisions of "WiringPi for RK3399"

Revision as of 05:32, 14 November 2018

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1 Introduction to WiringPi

The wiringPi library was initially developed by Gordon Henderson in C. It has libraries to access GPIO, I2C, SPI, UART, PWM and etc. Because its APIs are very similar to Arduino's APIs it is very popular among developers.
The wiringPi library has various libraries, header files and a commandline utility:gpio. The gpio utility can be used to read and write GPIO pins.

The wiringPi library was initially developed for BCM2835, and has been ported to FriendlyELEC-RK3399. It works with NanoPi M4, NanoPi NEO4 and NanoPC-T4.

Current version: 2.44
WiringPi's home page: http://wiringpi.com

FriendlyELEC has developed a Python version too and here is the reference link: WiringPi-Python for RK3399

2 Supported OS

• FriendlyCore
• FriendlyDesktop

Note: by default FriendlyELEC's latest ROMs already have the wiringPi utility. If a ROM doesn't have it you can refer to the instructions in this wiki to manually install it.

3 Supproted Boards

• NanoPC T4
• NanoPi M4
• NanoPi NEO4

4 Install WiringPi on T4/M4/NEO4

Log in a board(T4/M4/NEO4) via SSH and run the following commands:

# Delete "old" version
wget http://112.124.9.243:8888/wiringpi/friendlyelec-rk3399/remove_oldversion_wiringPi.sh
chmod 755 remove_oldversion_wiringPi.sh
sudo ./remove_oldversion_wiringPi.sh
# Download and install wiringPi for RK3399
wget http://112.124.9.243:8888/wiringpi/friendlyelec-rk3399/wiringpi-v2.44-friendlyelec-rk3399.deb
sudo dpkg -i  wiringpi-v2.44-friendlyelec-rk3399.deb

4.1 Test

You can test whether or not your installation is successful:

gpio readall

If your installation is successful your board's pin settings will be listed. For example here is a list of M4's pin settings:

root@NanoPi-M4:~# gpio readall
 +------+-----+----------+------+ Model  NanoPi-M4 +------+----------+-----+------+
 | GPIO | wPi |   Name   | Mode | V | Physical | V | Mode |   Name   | wPi | GPIO |
 +------+-----+----------+------+---+----++----+---+------+----------+-----+------+
 |      |     |     3.3V |      |   |  1 || 2  |   |      | 5V       |     |      |
 |      |     | I2C2_SDA |      |   |  3 || 4  |   |      | 5V       |     |      |
 |      |     | I2C2_SCL |      |   |  5 || 6  |   |      | GND(0V)  |     |      |
 |   32 |   7 | GPIO1_A0 |  OUT | 0 |  7 || 8  |   | ALT  | GPIO4_C1 | 15  |  145 |
 |      |     |  GND(0V) |      |   |  9 || 10 |   | ALT  | GPIO4_C0 | 16  |  144 |
 |   33 |   0 | GPIO1_A1 |   IN | 0 | 11 || 12 | 1 | IN   | GPIO1_C2 | 1   |  50  |
 |   35 |   2 | GPIO1_A3 |   IN | 0 | 13 || 14 |   |      | GND(0V)  |     |      |
 |   36 |   3 | GPIO1_A4 |   IN | 0 | 15 || 16 | 0 | IN   | GPIO1_C6 | 4   |  54  |
 |      |     |     3.3V |      |   | 17 || 18 | 0 | IN   | GPIO1_C7 | 5   |  55  |
 |      |     | UART4_TX |      |   | 19 || 20 |   |      | GND(0V)  |     |      |
 |      |     | UART4_RX |      |   | 21 || 22 | 0 | IN   | GPIO1_D0 | 6   |  56  |
 |      |     | SPI1_CLK |      |   | 23 || 24 |   |      | SPI1_CSn |     |      |
 |      |     |  GND(0V) |      |   | 25 || 26 |   | ALT  | GPIO4_C5 | 11  |  149 |
 |      |     | I2C2_SDA |      |   | 27 || 28 |   |      | I2C2_SCL |     |      |
 |      |     | I2S0_LRX |      |   | 29 || 30 |   |      | GND(0V)  |     |      |
 |      |     | I2S0_LTX |      |   | 31 || 32 |   |      | I2S_CLK  |     |      |
 |      |     | I2S0_SCL |      |   | 33 || 34 |   |      | GND(0V)  |     |      |
 |      |     | I2S0SDI0 |      |   | 35 || 36 |   |      | I2S0SDO0 |     |      |
 |      |     | I2S0I1O3 |      |   | 37 || 38 |   |      | I2S0I2O2 |     |      |
 |      |     |  GND(0V) |      |   | 39 || 40 |   |      | I2S0I3O1 |     |      |
 +------+-----+----------+------+---+----++----+---+------+----------+-----+------+
root@NanoPi-M4:~#

5 Code Samples Using wiringPi

Connect a Matrix - LED module to your board and make sure the hardware setting is as follows:

Here is a code sample showing how to make an LED blink using wiringPi
In the code sample '7' stands for 'Pin7':

5.1 Code Sample in C

Create a source file in C:

vi test.c

Type the following lines:

#include <wiringPi.h>
int main(void)
{
  wiringPiSetup() ;
  pinMode (7, OUTPUT) ;
  for(;;)
  {
    digitalWrite(7, HIGH) ;
    delay (500) ;
    digitalWrite(7,  LOW) ;
    delay (500) ;
  }
}

Compile the test.c file and run it:

gcc -Wall -o test test.c -lwiringPi -lwiringPiDev -lpthread -lrt -lm -lcrypt
sudo ./test

If everything is correct you will observe that the LED blinks.

5.2 Code Sample in Shell

Create a shell script:

vi test.sh

Type the following lines:

LED=7
gpio mode $LED out
while true; do
  gpio write $LED 1
  sleep 0.5
  gpio write $LED 0
  sleep 0.5
done

Run the script:

sudo source test.sh

If everything is correct you will observe that the LED blinks.

5.3 Code Sample in Python

You can refer to this link:WiringPi-Python for RK3399/zh

6 Regular APIs in WiringPi

6.1 Initialization

6.1.1 wiringPiSetup (void)

This function initializes wiringPi and uses the pin specifications defined by wiringPi. To check detailed pin specifications you can command "gpio readall".
You need to call this function as root.

6.1.2 int wiringPiSetupGpio(void)

This function is similar to the wiringPiSetup function. The only difference is that this function assumes the GPIO's pin specifications are the ones defined by CPU and haven't been redefined.
You need to call this function as root.

6.1.3 int wiringPiSetupPhys (void)

This function is similar to the wiringPiSetup function. The only difference is that it only supports P1's interface and doesn't support physical pin specifications.
You need to call this function as root.

6.1.4 int wiringPiSetupSys (void)

This function initializes wiringPi and access hardware by using "/sys/class/gpio" APIs rather than commanding hardware directly.
This function can be called by any users. The GPIO pin numbers used by this function should be the ones defined by CPU. This is similar to the rules followed by the wiringPiSetupGpio function.
Before calling this function make sure to call "/sys/class/gpio" APIs to list the pins you want to access.
You can list the pins you want to access in a separate shell script. Or you can command GPIO pins by calling "system()".

6.2 Core Functions

6.2.1 void pinMode (int pin, int mode)

This function sets a pin to INPUT, OUTPUT, PWM_OUTPUT or GPIO_CLOCK.
Note: after you call the wiringPiSetupSys function to access a pin calling this function will not make change that pin's mode.
You can set a pin's mode in a shell script.

6.2.2 void pullUpDnControl (int pin, int pud)

This function sets a pin to the pull-up or pull-down resistor mode when that pin is set to INPUT.
Unlike the Arduino the RK3399 has both the pull-up and pull-down resistor modes.
The parameter pud can be: PUD_OFF, (no pull up/down), PUD_DOWN (pull to ground) or PUD_UP (pull to 3.3v).
Note: after you call the wiringPiSetupSys function to access a pin calling this function will not make change that pin's mode.
If you need to activate a pull-up/pull-down resistor you can do it by using GPIO commands in a script before you start your program.

6.2.3 void digitalWrite (int pin, int value)

使用该函数可以向指定的管脚写入HIGH（高）或者LOW（低），写入前，需要将管脚设置为输出模式。
wiringPi将任何的非0值作为HIGH（高）来对待，因此，0是唯一能够代表LOW（低）的数值。

6.2.4 void pwmWrite (int pin, int value)

使用该函数可以将值写入指定管脚的PWM寄存器中，可设置的值为0~1024，其他PWM讴备可能有不同的PWM范围。
当在Sys模式时，该函数不可用来控制板上PWM。

6.2.5 digitalRead(int pin);

使用该函数可以读取指定管脚的值，读取到的值为HIGH（1）或者LOW（0），该值取决于该管脚的逻辑电平的高低。

6.2.6 analogRead (int pin) ;

该函数返回所指定的模拟输入管脚的值。你需要添加额外的模拟模块来使用该函数，比如Gertboard，quick2Wire模拟板等。

6.2.7 analogWrite (int pin, int value) ;

该函数将指定的值写入到指定的管脚。你需要添加额外的模拟模块来使用该函数，比如Gertboard等。

7 更新日志

7.1 2018-11-10

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