Issues with basic motion

Autonomous Machines Jetson & Embedded Systems Jetson Nano
#1

Hello,
i just setup my jetson nano development board and made it to open it remotly via Wifi and get to open the JupyterLab.
Here I wanted to start with the notebooks. The first one is the basic_motion. With the second command where he is supposed to initialize the Robot class the first errors appear. Can anyone give me an idea, what the problem could be.
Thank you in advance,
Matt

[2] robot = Robot()

–> the following error message appears.

OSErrorTraceback (most recent call last)
in
----> 1 robot = Robot()

/usr/local/lib/python3.6/dist-packages/jetbot-0.4.1-py3.6.egg/jetbot/robot.py in init(self, *args, **kwargs)
20 def init(self, *args, **kwargs):
21 super(Robot, self).init(*args, **kwargs)
—> 22 self.motor_driver = Adafruit_MotorHAT(i2c_bus=self.i2c_bus)
23 self.left_motor = Motor(self.motor_driver, channel=self.left_motor_channel, alpha=self.left_motor_alpha)
24 self.right_motor = Motor(self.motor_driver, channel=self.right_motor_channel, alpha=self.right_motor_alpha)

/usr/local/lib/python3.6/dist-packages/Adafruit_MotorHAT-1.4.0-py3.6.egg/Adafruit_MotorHAT/Adafruit_MotorHAT_Motors.py in init(self, addr, freq, i2c, i2c_bus)
229 self.motors = [ Adafruit_DCMotor(self, m) for m in range(4) ]
230 self.steppers = [ Adafruit_StepperMotor(self, 1), Adafruit_StepperMotor(self, 2) ]
–> 231 self._pwm = PWM(addr, debug=False, i2c=i2c, i2c_bus=i2c_bus)
232 self._pwm.setPWMFreq(self._frequency)
233

/usr/local/lib/python3.6/dist-packages/Adafruit_MotorHAT-1.4.0-py3.6.egg/Adafruit_MotorHAT/Adafruit_PWM_Servo_Driver.py in init(self, address, debug, i2c, i2c_bus)
57 self.i2c = get_i2c_device(address, i2c, i2c_bus)
58 logger.debug(“Reseting PCA9685 MODE1 (without SLEEP) and MODE2”)
—> 59 self.setAllPWM(0, 0)
60 self.i2c.write8(self.__MODE2, self.__OUTDRV)
61 self.i2c.write8(self.__MODE1, self.__ALLCALL)

/usr/local/lib/python3.6/dist-packages/Adafruit_MotorHAT-1.4.0-py3.6.egg/Adafruit_MotorHAT/Adafruit_PWM_Servo_Driver.py in setAllPWM(self, on, off)
93 def setAllPWM(self, on, off):
94 “Sets a all PWM channels”
—> 95 self.i2c.write8(self.__ALL_LED_ON_L, on & 0xFF)
96 self.i2c.write8(self.__ALL_LED_ON_H, on >> 8)
97 self.i2c.write8(self.__ALL_LED_OFF_L, off & 0xFF)

/usr/local/lib/python3.6/dist-packages/Adafruit_GPIO-1.0.4-py3.6.egg/Adafruit_GPIO/I2C.py in write8(self, register, value)
114 “”“Write an 8-bit value to the specified register.”""
115 value = value & 0xFF
–> 116 self._bus.write_byte_data(self._address, register, value)
117 self._logger.debug(“Wrote 0x%02X to register 0x%02X”,
118 value, register)

/usr/local/lib/python3.6/dist-packages/Adafruit_PureIO-1.1.7-py3.6.egg/Adafruit_PureIO/smbus.py in write_byte_data(self, addr, cmd, val)
320 # Send the data to the device.
321 self._select_device(addr)
–> 322 self._device.write(data)
323
324 def write_word_data(self, addr, cmd, val):

OSError: [Errno 121] Remote I/O error

#9

Hi funk.mat,

Thanks for reaching out!

This error is typically means that the Jetson nano is having trouble communicating with the motor driver over I2C. This arises from a few causes

  1. Hardware connection issue
  2. I2C permissions issue

Do you mind sharing which JetBot you are using, and the installation steps you took?

Best,
John

#10

Dear Johan,
Thank you for your answer. I followed this instruction:

I tried both versions:

Jetson Nano (4GB) 4.4.1 0.4.1 jetbot-041_nano-4gb-jp441.zip
Jetson Nano (4GB) 4.3 0.4.0 jetbot_image_v0p4p0.zip

Even though i am not 100% sure, which image is on the SD card now.
I switched the SDA & SCL pins, but this doesn’t solve the problem. I also checked the wiring on the OLED.
The power comes from a 5V- power adapter and goes directly to the NVIDIA board. I don’t use a battery pack.
The motor driver is connected and gets 5V from a USB-port of my PC.

Could that be the problem?

Kind regards,
Matthias

#13

Hi Matthias,

It’s possible insufficient power could cause issues. Assuming the entire system has enough power, are you able to use the following library (directly from jetson) to test the motors?

You should be able to easily install this on Jetson.

Please let me know if this helps or you have questions.

Best,
John

#15

Dear John,
thanks for your help. I connected the motor-driver board to a power supply at 5.5 V.
The jetson is connected to another power supply. I can access the jetbot via my windows PC and upload the scripts from the library that you recommended and start them in jupyter notebook scripts.
.
But it gives me always error massage like this one:
RuntimeErrorTraceback (most recent call last)
in
28 # - left_id: The ID of the left motor, default is 1.
29 # - right_id: The ID of the right motor, default is 2.
—> 30 robot = Robot.Robot(left_trim=LEFT_TRIM, right_trim=RIGHT_TRIM)
31
32 # Now move the robot around!

/workspace/jetbot/notebooks/HAT_Library/Robot.py in init(self, addr, left_id, right_id, left_trim, right_trim, stop_at_exit)
27 “”"
28 # Initialize motor HAT and left, right motor.
—> 29 self._mh = Adafruit_MotorHAT(addr)
30 self._left = self._mh.getMotor(left_id)
31 self._right = self._mh.getMotor(right_id)

/usr/local/lib/python3.6/dist-packages/Adafruit_MotorHAT-1.4.0-py3.6.egg/Adafruit_MotorHAT/Adafruit_MotorHAT_Motors.py in init(self, addr, freq, i2c, i2c_bus)
229 self.motors = [ Adafruit_DCMotor(self, m) for m in range(4) ]
230 self.steppers = [ Adafruit_StepperMotor(self, 1), Adafruit_StepperMotor(self, 2) ]
–> 231 self._pwm = PWM(addr, debug=False, i2c=i2c, i2c_bus=i2c_bus)
232 self._pwm.setPWMFreq(self._frequency)
233

/usr/local/lib/python3.6/dist-packages/Adafruit_MotorHAT-1.4.0-py3.6.egg/Adafruit_MotorHAT/Adafruit_PWM_Servo_Driver.py in init(self, address, debug, i2c, i2c_bus)
55
56 def init(self, address=0x40, debug=False, i2c=None, i2c_bus=None):
—> 57 self.i2c = get_i2c_device(address, i2c, i2c_bus)
58 logger.debug(“Reseting PCA9685 MODE1 (without SLEEP) and MODE2”)
59 self.setAllPWM(0, 0)

/usr/local/lib/python3.6/dist-packages/Adafruit_MotorHAT-1.4.0-py3.6.egg/Adafruit_MotorHAT/Adafruit_PWM_Servo_Driver.py in get_i2c_device(address, i2c, i2c_bus)
19 import Adafruit_GPIO.I2C as I2C
20 if i2c_bus is None:
—> 21 return I2C.get_i2c_device(address)
22 else:
23 return I2C.get_i2c_device(address, busnum=i2c_bus)

/usr/local/lib/python3.6/dist-packages/Adafruit_GPIO-1.0.4-py3.6.egg/Adafruit_GPIO/I2C.py in get_i2c_device(address, busnum, i2c_interface, **kwargs)
63 “”"
64 if busnum is None:
—> 65 busnum = get_default_bus()
66 return Device(address, busnum, i2c_interface, **kwargs)
67

/usr/local/lib/python3.6/dist-packages/Adafruit_GPIO-1.0.4-py3.6.egg/Adafruit_GPIO/I2C.py in get_default_bus()
55 return 1
56 else:
—> 57 raise RuntimeError(‘Could not determine default I2C bus for platform.’)
58
59 def get_i2c_device(address, busnum=None, i2c_interface=None, **kwargs):

RuntimeError: Could not determine default I2C bus for platform.

thanks agian for your help,
Matt

#16

… one thing i just figured out and want to add.
When I connect the motor driver board to 5 V the LED on the board is on. But i don’t get 3,3 V on the PINs on the opposite side of the 5 V connection like in this image.
Figure: motor driver board

#17

… i found the problem. There was some bad solderings.
Now it works.
Thanks. :-)

Matt

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