DF9GMS 180° Micro Servo

Hardware Information

Duo pinout

DF9GMS 180°

Micro Servo DF9GMS from DFRobot, this servo features a high-strength ABS transparent case with internal high-precision nylon gear set, precision control circuit and high-end lightweight hollow cup motor, resulting in a weight of only 9g for this mini servo, while the output torque reaches an amazing 1.6kg/cm.

Technical Specifications:
Operating Voltage: 4.8V
Torque: 1.6kg/cm (4.8V)
Speed: 0.14 seconds/60 degrees (4.8V)
Operating Temperature: -30 to +60 degrees Celsius
Deadband Width: 0.5 milliseconds
Physical Size: 23x12.2x29mm
Weight: 9g

Composition and Operating Principle of DF9GMS Micro Servo

Reference connection diagram

• Hardware
o 1 x Arduino UNO control board
o 1 x DF9GMS micro servo
o Several Dupont wires
o Gray - GND, red - VCC, yellow - signal line

connected to the development board

DF9GMS: red wire connected to VSYS, brown wire connected to ground, orange wire connected to GP4. Circuit diagram shown below: purple circle represents DF9GMS.

DF9GMS should be connected as follows:

Example Code:

GitHub link: https://github.com/milkv-duo/duo-examples

df9gms.c:

#include <stdio.h>
#include <unistd.h>
#include <wiringx.h>
/*
Duo
------------------------------------------
PWM operation at a fixed frequency clock of 100MHz, writing Period in units of nanoseconds.
	DF9GMS 360-degree PWM Duty Cycle 
	------------------------------------------ 
	0.4ms - 1.4ms CW deceleration 
	1.5ms Stop 
	1.6ms - 3ms CCW acceleration 
*/
static int PWM_PIN = 4; // PWM5@GP4

int main()
{
    long i;

    // Duo:     milkv_duo
    // Duo256M: milkv_duo256m
    // DuoS:    milkv_duos
    if(wiringXSetup("milkv_duo", NULL) == -1) {
        wiringXGC();
        return -1;
    }

    wiringXPWMSetPeriod(PWM_PIN, 20000000);  // 20ms
    wiringXPWMSetDuty(PWM_PIN, 1500000);     // 1.5ms stop
    wiringXPWMSetPolarity(PWM_PIN, 0);       // 0-normal, 1-inversed
    wiringXPWMEnable(PWM_PIN, 1);            // 1-enable, 0-disable

    delayMicroseconds(1000000); // 1s

    for (i = 10000; i< 3000000; i += 10000) // 10 us 
    {
        wiringXPWMSetDuty(PWM_PIN, i);
        printf("Duty: %ld\n", i);
        delayMicroseconds(50000); // 50ms
    }

    wiringXPWMSetDuty(PWM_PIN, 1500000);    // 1.5ms stop

    return 0;
}

Makefile：

TARGET=df9gms

ifeq (,$(TOOLCHAIN_PREFIX))
$(error TOOLCHAIN_PREFIX is not set)
endif

ifeq (,$(CFLAGS))
$(error CFLAGS is not set)
endif

ifeq (,$(LDFLAGS))
$(error LDFLAGS is not set)
endif

CC = $(TOOLCHAIN_PREFIX)gcc

CFLAGS += -I$(SYSROOT)/usr/include

LDFLAGS += -L$(SYSROOT)/lib
LDFLAGS += -L$(SYSROOT)/usr/lib
LDFLAGS += -lwiringx

SOURCE = $(wildcard *.c)
OBJS = $(patsubst %.c,%.o,$(SOURCE))

$(TARGET): $(OBJS)
	$(CC) -o $@ $(OBJS) $(LDFLAGS)

%.o: %.c
	$(CC) $(CFLAGS) -o $@ -c $<

.PHONY: clean
clean:
	@rm *.o -rf
	@rm $(OBJS) -rf
	@rm $(TARGET)

Build environment on Ubuntu20.04

You can also use Ubuntu installed in a virtual machine, Ubuntu installed via WSL on Windows, or Ubuntu-based systems using Docker.

Install the tools that compile dependencies.
```
sudo apt-get install wget git make
```

Get example source code

git clone https://github.com/milkv-duo/duo-examples.git

Prepare compilation environment
```
cd duo-examples
source envsetup.sh
```
The first time you source it, the required SDK package will be automatically downloaded, which is approximately 180MB in size. Once downloaded, it will be automatically extracted to the duo-examples directory with the name duo-sdk. When source it next time, if the directory already exists, it will not be downloaded again.
Compile testing

Take hello-world as an example, enter the hello-world directory and execute make
```
cd hello-world
make
```
After the compilation is successful, send the generated helloworld executable program to the Duo device through the network port or the USB network. For example, the USB-NCM method supported by the default firmware, Duo’s IP is 192.168.42.1, the user name is root, and the password is milkv
```
scp helloworld [email protected]:/root/
```
After sending successfully, run ./helloworld in the terminal logged in via ssh or serial port, and it will print Hello, World!
```
[root@milkv]~# ./helloworld
Hello, World!
```
At this point, our compilation and development environment is ready for use.