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z1rqdym
Joined: 14 Dec 2014
Posts: 24
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| MPU6050 Interfacing via I2C |
 Posted: Sun Dec 14, 2014 11:18 am |
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Hello everyone...
I'm making of quadcopter controller card and software with PIC18F4431 and GY-521 ( MPU6050 ) 3axis gyro + accel.
I have a problem about MPU6050 sensor.
I read a lot of things about it on this forum and in google...
so i am confused.
i learned I2C protocol well. my problem is not about that.
what is the mpu6050 device adress ? is it 0x68? 0x69? (these ones writing on the RM of the mpu6050 pdf.)
but on this forum i see that the device adress is 0xD0 or 0xD1.
in binary 0x68 = 01101000
0xD0 = 11010000
i see that the 0xD0 is shifted to left. why?
i2c use 7bit or 10bit data tarnsfer.
if its about 7bit data transfering maybe i could understand why 0x68 was shifted to left 1 bit.
if its that do like this should i do shifting to left all the data that i get from mpu6050? example for accel_x_high etc... to getting the right data from the sensor?
i write some code about to getting the gyro and accel data .
| Code: | int16 accel_x, gyro_x;
// reg_L is the adress for ACCEL_XOUT_L or GYRO_XOUT_L
// reg_H is the adress for ACCEL_XOUT_L or GYRO_XOUT_H
int16 MPU6050_READ_ACCEL_X(int reg_L, int reg_H)
{
unsigned int accel_x_h, accel_x_l;
i2c_start();
i2c_write(0x68);
i2c_write(reg_H);
i2c_start();
i2c_write(0x69);
accel_x_h=i2c_read(0);
i2c_stop();
delay_ms(50);
i2c_start();
i2c_write(0x68);
i2c_write(reg_L);
i2c_start();
i2c_write(0x69);
accel_x_l=i2c_read(0);
i2c_stop();
accel_x=make16(accel_x_h,accel_x_l);
return accel_x;
}
int16 MPU6050_READ_GYRO_X(int reg_L, int reg_H)
{
int gyro_x_h, gyro_x_l;
i2c_start();
i2c_write(0x68);
i2c_write(reg_H);
i2c_start();
i2c_write(0x69);
gyro_x_h=i2c_read(0);
i2c_stop();
delay_ms(50);
i2c_start();
i2c_write(0x68);
i2c_write(reg_L);
i2c_start();
i2c_write(0x69);
gyro_x_l=i2c_read(0);
i2c_stop();
gyro_x=make16(gyro_x_h,gyro_x_l);
return gyro_x;
} |
so is there any mistakes?
i can't write in english well but i can understand well  |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Sun Dec 14, 2014 11:56 am |
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also be sure to use proper logic level translators if you're running the PIC at 5 V ! As teh sensor is a 3V only device !!
it's always a great idea to run PCM Ps' 'i2C scanner program( on this forum) as a 'base line' test to confirm your PIC WILL access any I2C device.
jay |
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z1rqdym
Joined: 14 Dec 2014
Posts: 24
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| Posted: Sun Dec 14, 2014 12:14 pm |
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well, i read it and i understand it.
in the RegisterMap PDF of MPU6050 there write the DevAdress is 0x68.
that's mean in binary (MSB 0bX1101000 LSB) , the X is unimportent.
in i2c data transfering we send first the MSB to LSB . the last bit is R/W bit to say to slave IC to "I will read on you!" or "I will write to you!" is it right?
so we will shift left 1 bit to get first 7 bit MSB to LSB and then we have all ready the last bit to R/W too.
#define MPU6050_ADRESS 0x68
| Code: |
#define MPU6050_ADRESS 0x68
int16 accel_x, gyro_x;
// reg_L is the adress for ACCEL_XOUT_L or GYRO_XOUT_L
// reg_H is the adress for ACCEL_XOUT_L or GYRO_XOUT_H
int8 ADRESS_SHIFT_I2C_W(int8 adrss)
{
adress = adrss << 1;
return adress;
}
int8 ADRESS_SHIFT_I2C_R(int8 adrss)
{
adress = adrss << 1;
bit_set(adress,0);
return adress;
}
int16 MPU6050_READ_ACCEL_X(int reg_L, int reg_H)
{
unsigned int accel_x_h, accel_x_l;
i2c_start();
i2c_write(ADRESS_SHIFT(MPU6050_ADRESS));
i2c_write(reg_H);
i2c_start();
i2c_write(ADRESS_SHIFT_I2C_R(MPU6050_ADRESS));
accel_x_h=i2c_read(0);
i2c_stop();
delay_ms(50);
i2c_start();
i2c_write(ADRESS_SHIFT_I2C_W(MPU6050_ADRESS));
i2c_write(reg_L);
i2c_start();
i2c_write(ADRESS_SHIFT_I2C_R(MPU6050_ADRESS));
accel_x_l=i2c_read(0);
i2c_stop();
accel_x=make16(accel_x_h,accel_x_l);
return accel_x;
}
int16 MPU6050_READ_GYRO_X(int reg_L, int reg_H)
{
int gyro_x_h, gyro_x_l;
i2c_start();
i2c_write(ADRESS_SHIFT_I2C_W(MPU6050_ADRESS));
i2c_write(reg_H);
i2c_start();
i2c_write(ADRESS_SHIFT_I2C_R(MPU6050_ADRESS));
gyro_x_h=i2c_read(0);
i2c_stop();
delay_ms(50);
i2c_start();
i2c_write(ADRESS_SHIFT_I2C_W(MPU6050_ADRESS));
i2c_write(reg_L);
i2c_start();
i2c_write(ADRESS_SHIFT_I2C_R(MPU6050_ADRESS));
gyro_x_l=i2c_read(0);
i2c_stop();
gyro_x=make16(gyro_x_h,gyro_x_l);
return gyro_x;
}
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so i correct my code, is there now any mistakes? |
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z1rqdym
Joined: 14 Dec 2014
Posts: 24
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| Posted: Sun Dec 14, 2014 12:22 pm |
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I use 5V for my PIC18F4431. GY-521 has a low dropout regulator for 5V to 3,3V. and the sensors SDA and SCL pins are pull-up to 3,3V with 2,2kOhm resistors.
i read about this discussion too. some one makes it work without change anything. someone can't get ACK. maybe i should use 3,3V dsPIC.
but i haven't a programmer for dsPIC.
or i should use software I2C, with TTL buffered ports on the pic like portB.
if i will use software I2C, my quadcopters' responsiblity may be getting poor. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Dec 14, 2014 12:26 pm |
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| Quote: | | some one makes it work without change anything |
There is a large thread here on the MPU-6050 which tells you how to do it.
http://www.ccsinfo.com/forum/viewtopic.php?t=52866
Post a link to the website for your MPU-6050 board. |
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z1rqdym
Joined: 14 Dec 2014
Posts: 24
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| Posted: Sun Dec 14, 2014 12:45 pm |
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thanks a lot to PCM Programmer and thanks to you to temtronic for your responses
when i working my quadcopter i will take a video there |
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z1rqdym
Joined: 14 Dec 2014
Posts: 24
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| Posted: Tue Dec 16, 2014 6:06 am |
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http://www.ccsinfo.com/forum/viewtopic.php?t=52866&postdays=0&postorder=asc&start=15
the last thread on page2 that posted from PCM programmer,
I examine all the code and compare all of with the InvenSens MPU6000/6050 PDFs'.
So, I have new questions...
the first is, whats that mean
| Code: |
//-----------------------------------------
void Get_Accel_Angles()
{
accel_xangle = 57.295*atan((float)accel_yout/ sqrt(pow((float)accel_zout,2)+pow((float)accel_xout,2)));
accel_yangle = 57.295*atan((float)-accel_xout/ sqrt(pow((float)accel_zout,2)+pow((float)accel_yout,2)));
}
//--------------------------------------------------
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In this code I see to find the yangel by accelerometer. But why we are multiply the atan with 57.295?
accel_xout, accel_yout, accel_zout values are already g forces in hex/dec etc...
why we need to multiply 57,295 with atan?
and the second question is...
that question is about my level of c programming.
| Code: | | gyro_xrate = (float)gyro_xout/gyro_xsensitivity; |
| Code: | | gyro_xrate = gyro_xout/gyro_xsensitivity; |
whats the different in these codes? |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Tue Dec 16, 2014 6:20 am |
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I'll take a try..
1) the CCS 'math' library is coded for RADIANS not DEGREES...so you need to convert from radians to degrees.the 'magical' 57 number is the hint.
2) the first one 'casts'( forces) the result to be a floating point number regardless of the 'type' of the variables on the right side.
Jay |
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z1rqdym
Joined: 14 Dec 2014
Posts: 24
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| Posted: Tue Dec 16, 2014 6:33 am |
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Thanks for answering my first question.
"1radian = 180/Pi degrees" and 180/Pi = 57.295 thanks again
But I'm so sorry but your second answer. I didn't understand it :/
Could you tell a bit more detail, please? |
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z1rqdym
Joined: 14 Dec 2014
Posts: 24
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| Posted: Tue Dec 16, 2014 8:06 am |
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i thought about "(float)x/y;"
(float) makes the solution a float ? is it right? |
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z1rqdym
Joined: 14 Dec 2014
Posts: 24
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| Posted: Tue Dec 16, 2014 9:21 am |
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please help please :(
why are we multiply 1/400 with "gyro_xrate"
| Quote: |
dt=0,0025; //0,0025=1/400
gyro_xangle += gyro_xrate * dt;
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is gyro_xrate not already radian/s ?
if it's true, why don't we multiply with 57,295 as like for accel?
if it's false, how and where are we found the dt value 1/400=0,0025?
i think there is a mistake... |
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