MPU6050

[superbrew 0]

I have been getting familiar with the Tiva Launchpad and I have started working with the MPU6050. After some help from this forum, I was able to get it up and running and thought I would share some of my results. I have a goal of building a self balancing robot, but I am trying to take tiny steps to get there.

Here is a short video of my progress. I am still a long way off, but I am happy to be progressing.

 

 

PS, is there a way to embed youtube videos?

[bluehash 1,581]

Looks great for a first test!

 

I went ahead and embedded your video. Select the third icon and then media.

[Mr.Cruz 0]

Congrats on the progress! You might consider either running your refresh rate a bit higher, or using a better servo. Those smaller servos, in particular the one that was in the video, can be a bit jittery.

 

Do you have any of your code online? I've been working on a Robotics Booster Pack, and it also has a MPU6050. I'm able to pull the raw angles from it, but have yet to get the DMP in the IMU to work. Can't wait until I can start working with Quaternions!

[superbrew 0]

Thank you both for the replies.

 

Congrats on the progress! You might consider either running your refresh rate a bit higher, or using a better servo. Those smaller servos, in particular the one that was in the video, can be a bit jittery.

 

Do you have any of your code online? I've been working on a Robotics Booster Pack, and it also has a MPU6050. I'm able to pull the raw angles from it, but have yet to get the DMP in the IMU to work. Can't wait until I can start working with Quaternions!

I am thinking it is the servo, it is just a $3 servo, so I was not expecting much. I raised the refresh rate and increased the resolution of the PWM, but the behavior did not change that much. I suspect a lot of that has to do with my filter for the angle and my PID controller.

 

I do not have any code online. I am a beginner and my code most likely would not help you. I began by modifying the airmouse example, then added in a very simple complimentary filter for the angles. Then I added in the servo code, and a rudimentary PID controller. As I become more familiar with the Timer structure of these uC's I hope to imprive the filter and PID.

[pakoh 0]

Wouldn't mind to take a look at that dirty code.

 

Would you mind to share? I was trying to do something similar with mpu-9050 with no luck.

 

Thank you

[superbrew 0]

Here is the function I use to collect the data:

uint32_t newTicks;
float
MotionMain(uint32_t ticks)
{
	float gX, gY, gZ, aX, aY, aZ;
	float gyro_angle_x;
	static float oldAngle;
	volatile float dt;
	float alpha = 0.90;

	MPU6050DataRead(&g_sMPU6050Inst, MotionCallback, &g_sMPU6050Inst);

	MotionI2CWait(__FILE__, __LINE__);

	MPU6050DataGyroGetFloat(&g_sMPU6050Inst, &gX, &gY, &gZ);
	MPU6050DataAccelGetFloat(&g_sMPU6050Inst, &aX, &aY, &aZ);

	aX = ((atanf(aY/sqrtf(pow(aX,2)+pow(aZ,2))))*57.296) - g_faoffsetX;

	dt = (float)ticks/1000;

	gyro_angle_x = oldAngle + ((gX-g_fgoffsetX)*dt)*57.296;

	oldAngle = alpha*gyro_angle_x + (1-alpha)*aX;

	return oldAngle;
}

This is only for one axis, in this case X.

Here is the PID routine, I think there is much room for improvement here:

float PID(float setpoint, float input, float Kp, float Ki, float Kd)
{
	static float oldError;
	float error = setpoint - input;
	static float I_err;
	static float D_err;

	if(input > -0.5 && input < 0.5) error = 0;

	I_err += oldError;
	D_err  = error - oldError;

	oldError = error;
	return Kp*error + Ki*I_err + Kd*D_err;
}

And the main loop, this is messy and needs a lot of work:

    ticks = 0;
    oldticks = 0;

    //
    // Drop into the main loop.
    //
    oldticks = g_ui32SysTickCount;
    while(1)
    {
    	angle = MotionMain(ticks);

    	if(UARTPeek('\r') != -1)
    	{
    		UARTgets(command, sizeof(command));
			sscanf(command, "%f,%f,%f", &Kp, &Ki, &Kd);
    	}
		PIDangle = PID(0.0,angle, Kp, Ki, Kd);

    	ui8Adjust = round((-PIDangle));
    	if(firstTime != 0) ROM_PWMPulseWidthSet(PWM0_BASE, PWM_OUT_4, ui8Adjust * ui32Load / 1000);
    	firstTime = 1;
    	SysCtlDelay(SysCtlClockGet()/300);
        ticks = g_ui32SysTickCount - oldticks;
        oldticks = g_ui32SysTickCount;
    }

This code gets 'lost' easily. If I exceed the travel of the servo or move too quickly it can get stuck at one extreme or the other. I think this project is beyond my level for the time being, so I have put it on hold to work my way up.

[pakoh 0]

Thank you for sharing SuperBrew....

 

Do you think you are facing the same issue I had herewith the MPU-9150 present in the Sensorhub Boosterpack?:

 

 

http://e2e.ti.com/support/microcontrollers/tiva_arm/f/908/t/285768.aspx?pi297168=1

[Mr.Cruz 0]

Imo, it's definitely possible. It's a shame that the SensorHub code doesn't use the DMP in the MPU6050.

 

I've been considering porting the FreeIMU or equivalent MPU6050 code to the Tiva/Stellaris Launchpad since I want to make use of the DMP (I want my Quaternions!), but don't have an eta for it (I want to implement an I2C Master ISR first).

[pakoh 0]

Imo, it's definitely possible. It's a shame that the SensorHub code doesn't use the DMP in the MPU6050.

 

I've been considering porting the FreeIMU or equivalent MPU6050 code to the Tiva/Stellaris Launchpad since I want to make use of the DMP (I want my Quaternions!), but don't have an eta for it (I want to implement an I2C Master ISR first).

 

I do think the same, such a shame!!

 

If you port the MPU6050 to the Launchpad, please, don't hesitate on sharing it here. I think it could have a lot of applications, and probably, the MPU6050 used with FreeIMU is way more consistent.

 

Would also like to check that I2c Master ISR as well, I am using I2c with a DAC by writting directly the commands from the CPU.

 

Thank you.

[superbrew 0]

Not sure if this would help, but I use this firmware on my quadcopter, and I would say the yaw is stable on that. The board I am using in my quad uses an MPU6050 for the accel/gyro. Maybe digging through this will give you some ideas

 

https://github.com/MegaPirateNG

[happysmile09 0]

I am new to Tiva C, i wanna communicate TM4C123GH6PM to MPU 6050. But i have so many unclear points, 

1. Which I2C mode should i use among 4 modes: 

– Master transmit

– Master receive

– Slave transmit

– Slave receive

2. Do we have to configure the MPU 6050 module and what is the order should we do?

Thanks

[Mr.Cruz 0]

I do think the same, such a shame!!

 

If you port the MPU6050 to the Launchpad, please, don't hesitate on sharing it here. I think it could have a lot of applications, and probably, the MPU6050 used with FreeIMU is way more consistent.

 

Would also like to check that I2c Master ISR as well, I am using I2c with a DAC by writting directly the commands from the CPU.

 

Thank you.

 

@@pak, Unfortunately, I haven't had much luck porting the I2CDev implementation to the Tiva Launchpad.

 

I tried porting it before the competition, but was constantly getting values that didn't make sense (the quaternion was not stable at all. Looked more like gibberish). I gave it another shot last night, but still no go.

 

I've started looking into Invensense's library and am thinking I'll give that a shot instead. While I love the community around I2CDev, I trust the manufacturer to provide much better documentation and resources for the port. We'll see how that goes (might work on it this week).

 

The I2C + ISR implementation was halted due to other things taking priority, and I don't think I'll be resuming work on it for the forseable future. I'll post a link to my work as soon as I've uploaded the code.

 

 

@happysmile09: Your best bet at this moment would be to look at the Energia fork of the Arduino IDE and try using the I2CDev libraries with it. I would also suggest reading up on how I2C and the MPU6050 work.

[pakoh 0]

@@pak, Unfortunately, I haven't had much luck porting the I2CDev implementation to the Tiva Launchpad.

 

I tried porting it before the competition, but was constantly getting values that didn't make sense (the quaternion was not stable at all. Looked more like gibberish). I gave it another shot last night, but still no go.

 

I've started looking into Invensense's library and am thinking I'll give that a shot instead. While I love the community around I2CDev, I trust the manufacturer to provide much better documentation and resources for the port. We'll see how that goes (might work on it this week).

 

The I2C + ISR implementation was halted due to other things taking priority, and I don't think I'll be resuming work on it for the forseable future. I'll post a link to my work as soon as I've uploaded the code.

 

 

Thank you MrCruz.

 

I was playing again with MPU9150 without luck, but I already got two GY-521 boards, so I will test your code.

 

Looking forward to hear from you on this topic.

 

Regards

[GrumpyOldPizza 15]

Here some quick and dirty I2C/MPU6050 files. I am using bare metal, so there is not a lot of overhead. The interrupt handler and the enable/priority assignment is done by the RTOS I am using, so it's missing here. The only other RTOS feature used is that the ISR wakes up the calling task (wai_flg/set_flg). I could read the data off the MPU6050 with 1kHz sample rate.
 
Perhaps that will got you going quickly faster.
 

- Thomas
 
 
 

Thank you MrCruz.
 
I was playing again with MPU9150 without luck, but I already got two GY-521 boards, so I will test your code.
 
Looking forward to hear from you on this topic.
 
Regards

lm4f120_i2c.c

lm4f120_i2c.h

mpu6050.c

mpu6050.h

[pakoh 0]

Here some quick and dirty I2C/MPU6050 files. I am using bare metal, so there is not a lot of overhead. The interrupt handler and the enable/priority assignment is done by the RTOS I am using, so it's missing here. The only other RTOS feature used is that the ISR wakes up the calling task (wai_flg/set_flg). I could read the data off the MPU6050 with 1kHz sample rate.

 

Perhaps that will got you going quickly faster.

 

- Thomas

 Thank you  Thomas.

 

 

 

I am using TIvaware under CCS6 (which is free for Stellaris/Tiva devices).

What IDE did you use?

 

Regards