Matrix - Ultrasonic Ranger

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1 Introduction

Ultrasonic Ranger01

• The Matrix-Ultrasonic_Ranger is used to measure the distance.
• The module's sensor emits a sound wave, which bounces off a reflective surface and returns to the sensor. Then, using the amount of time it takes for the wave to return to the sensor, the distance to the object can be computed.

2 Features

• 5V Power
• Range: 5 cm - 300 cm，Accuracy: 1 cm
• One wire gpio
• PCB Dimension (mm): 20 x 40

• Pin Description:

Pin	Description
S	GPIO
V	Supply Voltage 5V
G	Ground

3 Basic Device Operation

• The sensor emits a 40kHz, 6 mm sound wave, which bounces off a reflective surface and returns to the sensor. The receiver converts ultrasound waves to electrical signals in mV.
• The master sends a signal to the module starting to emit a sound wave. After the module receives the returned signal it will will generate a high level indicating the elapsed time and the distance will be calculated by distance = (elapsed time * speed of sound)/2.

matrix Ultrasonic Ranger

4 Applications

4.1 Connect to NanoPi M1

Refer to the following connection diagram to connect the module to the NanoPi M1:

Connection Details:

Matrix-Ultrasonic_Ranger	NanoPi M1
S	Pin7
V	Pin4
G	Pin6

4.2 Connect to NanoPi 2

Refer to the following connection diagram to connect the module to the NanoPi 2:

Connection Details:

Matrix-Ultrasonic_Ranger	NanoPi 2
S	Pin7
V	Pin4
G	Pin6

4.3 Connect to NanoPi M2 / NanoPi 2 Fire

Refer to the following connection diagram to connect the module to the NanoPi M2/ NanoPi 2 Fire:

Connection Details:

Matrix-Ultrasonic_Ranger	NanoPi M2
S	Pin7
V	Pin4
G	Pin6

4.4 Connect to NanoPC-T2

Refer to the following connection diagram to connect the module to the NanoPC-T2:
Matrix-Ultrasonic_Ranger_NanoPC-T2

Connection Details:

Matrix-Ultrasonic_Ranger	NanoPC-T2
S	Pin15
V	Pin29
G	Pin30

5 Compile & Run Test Program

Boot your ARM board with Debian and copy the matrix code:

$ apt-get update && apt-get install git
$ git clone https://github.com/friendlyarm/matrix.git

If your cloning is done successfully a "matrix" directory will be generated.

Compile and install Matrix:

$ cd matrix
$ make && make install

Run test program:

$ matrix-ultrasonic_ranger

Note: this module is not plug and play therefore before running the module please make sure it is connected to an ARM board.
Here is what you should observe:

The distance is  24 cm

将超模波模块的正面对准待测距物体，测距完毕后程序会打印距离值。

6 代码说明

所有的开发板都共用一套Matrix代码，本模块的测试示例代码为matrix-ultrasonic_ranger，内容如下:

int main(int argc, char ** argv)
{
    int distance = -1;
    int pin = GPIO_PIN(7);
    int board;
 
    if ((board = boardInit()) < 0) {
        printf("Fail to init board\n");
        return -1;
    }
    if (board == BOARD_NANOPI_T2)
        pin = GPIO_PIN(15);
 
    system("modprobe "DRIVER_MODULE);
    if (Hcsr04Init(pin) == -1) {
        printf("Fail to init hcsr04\n");
        goto err;
    }
    if (Hcsr04Read(&distance) != -1) {
        printf("The distance is %3d cm\n", distance);
    } else {
        printf("Faid to get distance\n");
    }
    Hcsr04DeInit();
err:
    system("rmmod "DRIVER_MODULE);
 
    return 0;
}

API说明参考维基：Matrix API reference manual

8 Update Log

8.1 Feb-23-2016

• Added the description for "NanoPi 2 branch" in Section 4
• Added Section 5: Connect to NanoPi 2