I2C Sensors with RNBO and Bela Gem

tmarasco125

Hi there!

I'm interested in using various I2C sensors to control parameters in a RNBO patch on my Bela Gem. I wanted to know what the process would be for accessing data from sensors of I2C would be and if there would need to be modifications from one sensor to the next since they'd each mostlikely format and output their data differently. I'm assuming that custom code would need to be written in the render.cpp file, correct? If a sensor has an available Arduino library/driver (like this MPU6050 accelerometer from Adafruit), would those libraries need to be included in the RNBO project directories and referenced in the render.cpp file? Would function calls from the library be used in the custom C++ code put in render to access the data and map it to parameters in the RNBO code?

Thanks in advance for guidance on this!

giuliomoro

assuming that custom code would need to be written in the render.cpp file, correct?

Yes

tmarasco125 Would function calls from the library be used in the custom C++ code put in render to access the data and map it to parameters in the RNBO code?

Yes. You'll need a thread to read the sensors and prepare the data, then from the audio thread (the render() function) you'd assign the values to what you want to control. See how it's done for Trill in the cpp file already.

tmarasco125 sensor has an available Arduino library/driver (like this MPU6050 accelerometer from Adafruit), would those libraries need to be included in the RNBO project directories

Yes, but they will need some wrangling to make them work. More than I wish it did. I made an example for you, see if it works? https://github.com/giuliomoro/Adafruit_MPU6050

tmarasco125

Thank you for your help with getting started on this! I have a few follow up questions:

When adding the modified MPU6050 library to the rnbo.example.bela repo to compile on the Bela, where should the library be placed? If I need to include it in the render.cpp file, is there a default directory location in the project where it should be located?

In the render.cpp, would an example of a thread to grab the sensor readings from the MPU6050 library calls look something like this function found on line 86?:

#ifdef BELA_RNBO_USE_TRILL
static void loop(void*)
{
	while(!Bela_stopRequested())
	{
		for(auto& t : trills)
			t->readI2C();
		usleep(5000);
	}
}
#endif // BELA_RNBO_USE_TRILL

In the audio thread/render() function, is the applicable code to see how Trill sensor data is mapped to RNBO parameters found on line 350?:

#ifdef BELA_RNBO_USE_TRILL
	auto trillShouldSend = trillHold ? [](unsigned int c) -> bool { return trills[c]->compoundTouchSize() > 0; } : [](unsigned int c) -> bool { return true; };
	sendOnChange(trillLocationParametersPast, parametersFromTrillLocation, &trillGetTouches<&Trill::touchLocation, &Trill::compoundTouchLocation>,
			nullptr, trillShouldSend);
	sendOnChange(trillHorizontalLocationParametersPast, parametersFromTrillHorizontalLocation, &trillGetTouches<&Trill::touchHorizontalLocation, &Trill::compoundTouchHorizontalLocation>,
			nullptr, trillShouldSend);
	sendOnChange(trillSizeParametersPast, parametersFromTrillSize, &trillGetTouches<&Trill::touchSize, &Trill::compoundTouchSize>, nullptr, trillShouldSend);
#endif // BELA_RNBO_USE_TRILL

Also: in the new forked repo of the library you sent as an example, there is a render.cpp file. Is this an example of code that should go into the primary render.cpp file included in every RNBO project, or is this a second, seperate file that is needed in order for the library to work and it should be kept in the same location as the rest of the MPU6050 library files?

giuliomoro

the code I sent is a stand-alone example to validate that the library works. Try running that as it is.

tmarasco125

Hello! I've uploaded the repo and ran it to test the build. It looks like it worked as a starting build! I don't have my MPU6050 on my as I'm traveling, but here it the console output that I got after the libraries finished building:
make:...done Build finished Running project... Failed to do ioctl for 1 bytes on I2C at addr 104 with flags 1: -1 Failed to do ioctl for 1 bytes on I2C at addr 104 with flags 1: -1 Failed to do ioctl for 1 bytes on I2C at addr 104 with flags 1: -1 Failed to do ioctl for 1 bytes on I2C at addr 104 with flags 1: -1 Failed to do ioctl for 1 bytes on I2C at addr 104 with flags 1: -1 Failed to find MPU6050 chip Error: unable to initialise audio make: *** [Makefile:745: runide] Error 1 Bela stopped

Since there is no audio code in the project, the error with the audio initialization failure to be expected correct?

What would be the next step for integrating this into the default render.cpp in RNBO projects?

giuliomoro

tmarasco125 don't have my MPU6050 on my as I'm traveling, but here it the console output that I got after the libraries finished building:

I get the same, it's because the sensor is not connected. So...connect one up and see if you are lucky.

"unable to initalise audio" is printed when setup() returns false. In this case, it returns false because the sensor initialisation fails.

tmarasco125

giuliomoro Great! I will try this again next week when I can get back to my sensor. In the meantime, could you explain how you modified the MPU6050 library in order to get it to build on the Bela? I'd like to work on applying that to other Adafruit libraries that work with additional sensors but could use a description of how the process works if you don't mind.

giuliomoro

There's a BelaArduino library on the board, where I implemented a minimal set of Arduino functions and classes. There I implement Wire and also include the I2C files from here https://github.com/adafruit/Adafruit_BusIO. I didn't include all of the Adafruit_BusIO stuff because I didn't have time to sort the SPI one out and I didn't understand the purpose of the "Generic" one.
So for some sensors, it "just works" when dropping in the sensor-specific files and changing the includes to libraries/BelaArduino/{Wire.h,Arduino.h}. However, this specific library also uses https://github.com/adafruit/adafruit_sensor and more files from https://github.com/adafruit/Adafruit_BusIO . So what I did here was to:

import the additional files that were needed
fix the includes
amend such files so that they wouldn't reference any of the SPI and Generic stuff

If I had more time, I would instead adapt the Generic and SPI stuff so that it just works and include it all in the BelaArduino library, or at least include the modified files without SPI support.

Note: BelaArduino goes much beyond this: it additionally contains files to run an Arduino-like file (with void setup() and void loop()), to use Bela's digitals and analogs for Arduino's digitalRead(), digitalWrite(), analogRead(), analogWrite(), adds pwmWrite() and support for shift registers and a messaging system to communicate with the Bela audio thread and support to run a PureData patch alongside all of this and pass data between Pd and Arduino. See the Arduino examples on the board.
You don't need any of these for your application I think, but this explains why I had to define some dummy functions here.

tmarasco125

Hello again! I'm back in front of my MPU6050 sensor and I'm unfortunately running into errror messages even with the sensor attached to the Bela. The sensor isn't being initialized when the project runs.

I've tried attaching the sensor through the built in QWIIC connector on the Gem Stereo and I've also tried connecting it to the pin sockets. I get different error messages with both connection approaches:

Here are the error messages I get with each connection approach:

When connecting to the pin sockets:
Building project... Build finished Running project... Failed to do ioctl for 1 bytes on I2C at addr 104 with flags 1: -1 Failed to do ioctl for 1 bytes on I2C at addr 104 with flags 1: -1 Failed to do ioctl for 1 bytes on I2C at addr 104 with flags 1: -1 Failed to do ioctl for 1 bytes on I2C at addr 104 with flags 1: -1 Failed to do ioctl for 1 bytes on I2C at addr 104 with flags 1: -1 Failed to find MPU6050 chip Error: unable to initialise audio make: *** [Makefile:745: runide] Error 1 Bela stopped

When connecting to the built-in QWIIC connector:
Building project... Build finished Running project... Failed to find MPU6050 chip Error: unable to initialise audio make: *** [Makefile:745: runide] Error 1 Bela stopped

I haven't had any errors when building the MPU6050 libraries that I can see, but is it possible that one of them isn't building and the sensor isn't initializing?

giuliomoro

tmarasco125 When connecting to the pin sockets:

What pins are you using here?

run i2cdetect -y -r 1 in the console at the bottom of the IDE to see if the sensor comes up at the expected address.

tmarasco125

Hi there,

Connecting the sensor to the QWIIC connector and running the i2cdetect command in the console looks like it shows the sensor being recognized. The console returns this:

0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- --

And on the sensor's intel page on Adafruit, the default address is 0X68.

giuliomoro What pins are you using here?

When I tried connecting the sensor to the pins instead of the quick connector, I was using 3.3v, Ground, SDA, and SCL. But I may have had the SDA and SCL wires connected to the wrong pins, so now I get the same set of errors no matter how I connect the sensor and the Bela recognizes the sensor through querying the console both ways. The render file does not recognize that the sensor has been connected and initialized though.

giuliomoro

OK that's the correct address, the wires are correct. The fact that the "ioctl" errors disappear mean it's talking to the actual device and the device is responding, still there's something that prevents the device from initialising correctly and mpu.begin() returns false. To figure out why, in Adafruit_MPU6050.cpp, find the implementation of Adafruit_MPU6050::begin and add printf statements so that we can see which of the return false; statements is executed. If it's the second one, then also add print printf("%#x\n\r", chip_id.read()); before return false.

tmarasco125

Hi again,

It looks like the first return false; statement is the one that prints out. I looked at this block of code in Adafruit_MPU6050.cpp: https://github.com/giuliomoro/Adafruit_MPU6050/blob/8aac6d7732bf39d61b60e96309ba9b69052883ba/Adafruit_MPU6050.cpp#L78-L88

And I added printf("It's the first one!"); right before the return false; at line 88. The Bela IDE console returned:

Build finished Running project... It's the first one!Failed to find MPU6050 chip Error: unable to initialise audio make: *** [Makefile:745: runide] Error 1 Bela stopped

giuliomoro

did you use parentheses for the whole block?

You need something like this:

bool Adafruit_MPU6050::begin(uint8_t i2c_address, TwoWire *wire,
                             int32_t sensor_id) {
  if (i2c_dev) {
    delete i2c_dev; // remove old interface
  }

  i2c_dev = new Adafruit_I2CDevice(i2c_address, wire);

  // For boards with I2C bus power control, may need to delay to allow
  // MPU6050 to come up after initial power.
  bool mpu_found = false;
  for (uint8_t tries = 0; tries < 5; tries++) {
    mpu_found = i2c_dev->begin();
    if (mpu_found)
      break;
    delay(10);
  }
  if (!mpu_found) {
    printf("It's the first one\n");
    return false;
  }

  Adafruit_BusIO_Register chip_id =
      Adafruit_BusIO_Register(i2c_dev, MPU6050_WHO_AM_I, 1);

  // make sure we're talking to the right chip
  if (chip_id.read() != MPU6050_DEVICE_ID) {
    printf("It's the second one: chip_id %#x\n", chip_id.read());
    return false;
  }

  return _init(sensor_id);
}

tmarasco125

Thanks for that! I missed the need for braces. I swapped in the code you wrote in your last post and the error message still prints that the first init test is what is failing. Here is the full console code when building:

Building project... Building Adafruit_MPU6050.cpp... ...done Using library BelaArduino Using library BelaLibpd Using library Fft Using library Gui Using library Midi Using library Scope Using library Serial Using library ShiftRegister Using library Trill Using library WSServer Using library libpd Using library ne10 Linking... ...done Build finished Running project... It's the first one Failed to find MPU6050 chip Error: unable to initialise audio make: *** [Makefile:745: runide] Error 1 Bela stopped root@bela:~/Bela#
And when running the I2C Device check command, the sensor is still able to be found at the correct address.

giuliomoro

It may be a spurious failure, try this instead:

bool Adafruit_MPU6050::begin(uint8_t i2c_address, TwoWire *wire,
                             int32_t sensor_id) {
  if (i2c_dev) {
    delete i2c_dev; // remove old interface
  }

  i2c_dev = new Adafruit_I2CDevice(i2c_address, wire);

  // For boards with I2C bus power control, may need to delay to allow
  // MPU6050 to come up after initial power.
  bool mpu_found = false;
  for (uint8_t tries = 0; tries < 5; tries++) {
    mpu_found = i2c_dev->begin();
    if (mpu_found)
      break;
    delay(10);
  }
  if (!mpu_found) {
    wire->beginTransmission(i2c_address);
    int ret = wire->endTransmission();
    printf("first one: endtransmission returned %d\n", ret);
  }

  Adafruit_BusIO_Register chip_id =
      Adafruit_BusIO_Register(i2c_dev, MPU6050_WHO_AM_I, 1);

  // make sure we're talking to the right chip
  if (chip_id.read() != MPU6050_DEVICE_ID) {
    printf("It's the second one: chip_id %#x\n", chip_id.read());
    return false;
  }

  return _init(sensor_id);
}

tmarasco125

Success! That change did the trick, thank you! I do get a print out from the first check that says first one: endtransmission returned 1, but that's immediatley followed by MPU6050 Found! logged from the render file. It then get sensor values printed out continuously as seen below:

Building project...
Build finished
Running project...
first one: endtransmission returned 1
MPU6050 Found!
Accelerometer range set to: +-8G
Gyro range set to: +- 500 deg/s
Filter bandwidth set to: 21 Hz
Acceleration X: 3.00712, Y: 2.8898, Z: 4.84826 m/s^2
Rotation X: -0.0586217, Y: -0.00319755, Z: -0.0255804 rad/s
Temperature: 28.1859 degC

Acceleration X: 4.42688, Y: 4.24492, Z: 7.15387 m/s^2
Rotation X: -0.0580888, Y: -0.00293109, Z: -0.0250475 rad/s
Temperature: 28.2035 degC

Acceleration X: 4.4197, Y: 4.26407, Z: 7.14909 m/s^2
Rotation X: -0.0588882, Y: -0.00239816, Z: -0.0253139 rad/s
Temperature: 28.2006 degC

If these values are printing, at this point can they be mapped to RNBO parameters? If so, how would I integrate that into the standard RNBO project render.cpp?

giuliomoro

you'll start from including those files in the rnbo project, then in render.cpp follow the blueprint of anything Trill:

above setup()

#include <Adafruit_MPU6050.h>

// dummy functions for BelaArduino
void loop() {}
void setup() {}

Adafruit_MPU6050 mpu;
sensors_event_t accel, gyro, temp;

void mpu6050Loop(void*) {
	while(!Bela_stopRequested()) {
		mpu.getEvent(&a, &g, &temp);
		usleep(100000);
	}
}

in setup()

	// Try to initialize!
	if (!mpu.begin()) {
	    Serial.println("Failed to find MPU6050 chip");
		return false;
	}
	Serial.println("MPU6050 Found!");
	
	mpu.setAccelerometerRange(MPU6050_RANGE_8_G);
	Serial.print("Accelerometer range set to: ");
	switch (mpu.getAccelerometerRange()) {
	case MPU6050_RANGE_2_G:
	Serial.println("+-2G");
	break;
	case MPU6050_RANGE_4_G:
	Serial.println("+-4G");
	break;
	case MPU6050_RANGE_8_G:
	Serial.println("+-8G");
	break;
	case MPU6050_RANGE_16_G:
	Serial.println("+-16G");
	break;
	}
	mpu.setGyroRange(MPU6050_RANGE_500_DEG);
	Serial.print("Gyro range set to: ");
	switch (mpu.getGyroRange()) {
	case MPU6050_RANGE_250_DEG:
	Serial.println("+- 250 deg/s");
	break;
	case MPU6050_RANGE_500_DEG:
	Serial.println("+- 500 deg/s");
	break;
	case MPU6050_RANGE_1000_DEG:
	Serial.println("+- 1000 deg/s");
	break;
	case MPU6050_RANGE_2000_DEG:
	Serial.println("+- 2000 deg/s");
	break;
	}
	
	mpu.setFilterBandwidth(MPU6050_BAND_21_HZ);
	Serial.print("Filter bandwidth set to: ");
	switch (mpu.getFilterBandwidth()) {
	case MPU6050_BAND_260_HZ:
	Serial.println("260 Hz");
	break;
	case MPU6050_BAND_184_HZ:
	Serial.println("184 Hz");
	break;
	case MPU6050_BAND_94_HZ:
	Serial.println("94 Hz");
	break;
	case MPU6050_BAND_44_HZ:
	Serial.println("44 Hz");
	break;
	case MPU6050_BAND_21_HZ:
	Serial.println("21 Hz");
	break;
	case MPU6050_BAND_10_HZ:
	Serial.println("10 Hz");
	break;
	case MPU6050_BAND_5_HZ:
	Serial.println("5 Hz");
	break;
	}

	Bela_runAuxiliaryTask(mpuLoop);

At the top of render(), send the parameters you need. The parameter index (first argument) should match the index
the desired one in the list of exposed parameters that is printed when the program starts. Here are some examples:

rnbo->setParameterValue(0, accel.acceleration.x);
rnbo->setParameterValue(1, gyro.gyro.y);
rnbo->setParameterValue(2, temp.temperature);