Binary Communications Example Project¶

This IS Communications Example project demonstrates binary communications with the
Inertial Sense Products (IMX, uAHRS, and uIMU) using the Inertial Sense SDK.

Files¶

Project Files¶

ISCommunicationsExample.c

SDK Files¶

Implementation¶

Step 1: Add Includes¶

// Change these include paths to the correct paths for your project
#include "../../src/ISComm.h"
#include "../../src/serialPortPlatform.h"
#include "../../src/ISPose.h"

Step 2: Init comm instance¶

    is_comm_instance_t comm;
    uint8_t buffer[2048];

    // Initialize the comm instance, sets up state tracking, packet parsing, etc.
    is_comm_init(&comm, buffer, sizeof(buffer));

Step 3: Initialize and open serial port¶

    serial_port_t serialPort;

    // Initialize the serial port (Windows, MAC or Linux) - if using an embedded system like Arduino,
    //  you will need to handle the serial port creation, open and reads yourself. In this
    //  case, you do not need to include serialPort.h/.c and serialPortPlatform.h/.c in your project.
    serialPortPlatformInit(&serialPort);

    // Open serial, last parameter is a 1 which means a blocking read, you can set as 0 for non-blocking
    // you can change the baudrate to a supported baud rate (IS_BAUDRATE_*), make sure to reboot the IMX
    //  if you are changing baud rates, you only need to do this when you are changing baud rates.
    if (!serialPortOpen(&serialPort, argv[1], IS_BAUDRATE_921600, 1))
    {
        printf("Failed to open serial port on com port %s\r\n", argv[1]);
        return -2;
    }

Step 4: Stop any message broadcasting¶

    int messageSize = is_comm_stop_broadcasts_all_ports(comm);
    if (messageSize != serialPortWrite(serialPort, comm->buf.start, messageSize))
    {
        printf("Failed to encode and write stop broadcasts message\r\n");
    }

Step 5: Set configuration (optional)¶

    // Set INS output Euler rotation in radians to 90 degrees roll for mounting
    float rotation[3] = { 90.0f*C_DEG2RAD_F, 0.0f, 0.0f };
    int messageSize = is_comm_set_data(comm, _DID_FLASH_CONFIG, offsetof(nvm_flash_cfg_t, insRotation), sizeof(float) * 3, rotation);
    if (messageSize != serialPortWrite(serialPort, comm->buf.start, messageSize))
    {
        printf("Failed to encode and write set INS rotation\r\n");
    }

Step 6: Enable message broadcasting¶

    // Ask for INS message w/ update 40ms period (4ms source period x 10).  Set data rate to zero to disable broadcast and pull a single packet.
    int messageSize = is_comm_get_data(comm, _DID_INS_LLA_EULER_NED, 0, 0, 10);
    if (messageSize != serialPortWrite(serialPort, comm->buf.start, messageSize))
    {
        printf("Failed to encode and write get INS message\r\n");
    }

    // Ask for GPS message at period of 200ms (200ms source period x 1).  Offset and size can be left at 0 unless you want to just pull a specific field from a data set.
    messageSize = is_comm_get_data(comm, _DID_GPS1_POS, 0, 0, 1);
    if (messageSize != serialPortWrite(serialPort, comm->buf.start, messageSize))
    {
        printf("Failed to encode and write get GPS message\r\n");
    }

    // Ask for IMU message at period of 96ms (DID_FLASH_CONFIG.startupNavDtMs (16ms default) source period x 6).  This could be as high as 1000 times a second (period multiple of 1)
    messageSize = is_comm_get_data(comm, _DID_IMU, 0, 0, 6);
    if (messageSize != serialPortWrite(serialPort, comm->buf.start, messageSize))
    {
        printf("Failed to encode and write get IMU message\r\n");
    }

Step 7: Save Persistent Messages¶

(OPTIONAL) Save currently enabled streams as persistent messages enabled after reboot.

    system_command_t cfg;
    cfg.command = SYS_CMD_SAVE_PERSISTENT_MESSAGES;
    cfg.invCommand = ~cfg.command;

    int messageSize = is_comm_set_data(comm, DID_SYS_CMD, 0, sizeof(system_command_t), &cfg);
    if (messageSize != serialPortWrite(serialPort, comm->buf.start, messageSize))
    {
        printf("Failed to write save persistent message\r\n");
    }

Step 8: Handle received data¶

    int count;
    uint8_t inByte;

    // You can set running to false with some other piece of code to break out of the loop and end the program
    while (running)
    {
        // Read one byte with a 20 millisecond timeout
        while ((count = serialPortReadCharTimeout(&serialPort, &inByte, 20)) > 0)
        {
            switch (is_comm_parse_byte(&comm, inByte))
            {
            case _PTYPE_INERTIAL_SENSE_DATA:
                switch (comm.dataHdr.id)
                {
                case _DID_INS_LLA_EULER_NED:
                    handleIns1Message((ins_1_t*)comm.dataPtr);
                    break;

                case DID_INS_2:
                    handleIns2Message((ins_2_t*)comm.dataPtr);
                    break;

                case _DID_GPS1_POS:
                    handleGpsMessage((gps_pos_t*)comm.dataPtr);
                    break;

                case _DID_IMU_DUAL:
                    handleImuMessage((dual_imu_t*)comm.dataPtr);
                    break;

                // TODO: add other cases for other data ids that you care about
                }
                break;

            default:
                break;
            }
        }
    }

Compile & Run (Linux/Mac)¶

Create build directory

$ cd InertialSenseSDK/ExampleProjects/Communications
$ mkdir build

Run cmake from within build directory
```
$ cd build
$ cmake ..
```
Compile using make
```
$ make
```
If necessary, add current user to the "dialout" group in order to read and write to the USB serial communication ports:
```
$ sudo usermod -a -G dialout $USER
$ sudo usermod -a -G plugdev $USER
(reboot computer)
```

Run executable

$ ./ISCommunicationsExample /dev/ttyUSB0

Compile & Run (Windows MS Visual Studio)¶

Install and Configure Visual Studio
Open Visual Studio solution file (InertialSenseSDK\ExampleProjects\Communications\VS_project\ISCommunicationsExample.sln)
Build (F7)

Run executable

C:\InertialSenseSDK\ExampleProjects\Communications\VS_project\Release\ISCommunicationsExample.exe COM3

Summary¶

This section has covered the basic functionality you need to set up and communicate with Inertial Sense products. If this doesn't cover everything you need, feel free to reach out to us on the Inertial Sense SDK GitHub repository, and we will be happy to help.