Introduction
wiringX is a library that allows developers to control the GPIO of various platforms with generic and uniform functions. By using wiringX, the same code will run on all platforms supported by wiringX, natively.
This article will be divided into the following four parts to introduce how to develop applications on Duo using wiringX:
- wiringX APIs
- Basic usage code demonstration
- Configuration of the application compilation environment based on wiringX
- Introduction to some demos and projects implemented using wiringX
If you are already familiar with the usage of wiringX, you can directly refer to our sample code: duo-examples
The wiringX pin numbering of Milk-V Duo is consistent with the pin name numbering of Duo. However, the LED control pin is not available on the 40-pin physical pinout, and its wiringX pin number is 25
.
wiringX | PIN NAME | Pin# | Pin# | PIN NAME | wiringX |
---|---|---|---|---|---|
0 | GP0 | 1 | 40 | VBUS | |
1 | GP1 | 2 | 39 | VSYS | |
GND | 3 | 38 | GND | ||
2 | GP2 | 4 | 37 | 3V3_EN | |
3 | GP3 | 5 | 36 | 3V3(OUT) | |
4 | GP4 | 6 | 35 | ||
5 | GP5 | 7 | 34 | ||
GND | 8 | 33 | GND | ||
6 | GP6 | 9 | 32 | GP27 | 27 |
7 | GP7 | 10 | 31 | GP26 | 26 |
8 | GP8 | 21 | 30 | RUN | |
9 | GP9 | 12 | 29 | GP22 | 22 |
GND | 13 | 28 | GND | ||
10 | GP10 | 14 | 27 | GP21 | 21 |
11 | GP11 | 15 | 26 | GP20 | 20 |
12 | GP12 | 16 | 25 | GP19 | 19 |
13 | GP13 | 17 | 24 | GP18 | 18 |
GND | 18 | 23 | GND | ||
14 | GP14 | 19 | 22 | GP17 | 17 |
15 | GP15 | 20 | 21 | GP16 | 16 |
25 | GP25 | LED |
Please note that many of Duo's pins have multipurpose functionality. When using wiringX
to control the functions of each pin, it is important to confirm the current state of the pin to ensure it matches the desired functionality. If it doesn't, you can use the duo-pinmux
command to switch it to the desired function.
Please refer to the detailed usage instructions for more information:pinmux.
1. Code example
GPIO Usage Example
Here is an example of working with GPIO. It will toggle pin 20 on Duo every 1 second, pulling it high and then low. The physical pin number for pin 20 is 15
in the WiringX numbering system.
#include <stdio.h>
#include <unistd.h>
#include <wiringx.h>
int main() {
int DUO_GPIO = 15;
if(wiringXSetup("duo", NULL) == -1) {
wiringXGC();
return -1;
}
if(wiringXValidGPIO(DUO_GPIO) != 0) {
printf("Invalid GPIO %d\n", DUO_GPIO);
}
pinMode(DUO_GPIO, PINMODE_OUTPUT);
while(1) {
printf("Duo GPIO (wiringX) %d: High\n", DUO_GPIO);
digitalWrite(DUO_GPIO, HIGH);
sleep(1);
printf("Duo GPIO (wiringX) %d: Low\n", DUO_GPIO);
digitalWrite(DUO_GPIO, LOW);
sleep(1);
}
return 0;
}
After compiling and running it on Duo, you can use a multimeter or an oscilloscope to measure the state of pin 20 and verify if it matches the expected behavior.
You can also use the onboard LED pin to verify the behavior. By observing the on/off state of the LED, you can intuitively determine if the program is executing correctly. The WiringX pin number for the LED is 25
. Simply modify the code mentioned above by replacing pin 15
with pin 25
. However, please note that the default firmware has a script to control LED blinking on startup, which needs to be disabled. You can refer to the example explanation for blink below for instructions on how to disable it.
I2C Usage Example
Here is an example of I2C communication:
#include <stdio.h>
#include <unistd.h>
#include <stdint.h>
#include <wiringx.h>
#define I2C_DEV "/dev/i2c-1"
#define I2C_ADDR 0x04
int main(void)
{
int fd_i2c;
int data = 0;
if(wiringXSetup("duo", NULL) == -1) {
wiringXGC();
return -1;
}
if ((fd_i2c = wiringXI2CSetup(I2C_DEV, I2C_ADDR)) <0) {
printf("I2C Setup failed: %d\n", fd_i2c);
wiringXGC();
return -1;
}
// TODO
}