Supported Hardware

Microcontroller Peripherals

Raw pins

$ rosservice call /mirte/get_pin_value "{pin: '', type: ''}"
$ rosservice call /mirte/set_pin_value "{pin: '', type: '', value: }"

Setting a pin can be either ‘analog’ (PWM) or ‘digital’. The pin itself can be defined as the print on the MCU (e.g. ‘GP3’). You can have a look in the web interface to see all options.

Warning

Currently there is no check on whether a pin is already in use by some hardware defined in the yaml configuration discussed earlier. Therefore there is no expected behavior when using getting or setting raw pins.

DC Motor

Depending on the interface of your motor controller, the DC motor can be controlled though three different interfaces:

  • ddp (digital, digital, pwm): This interface uses two digital pins to set the direction of the motor, and uses a PWM dignal to set the speed. The L298 can use this interface.

  • dp (digital, pwm): This interface uses one digital pin for teh direction, and pwm for the speed. The downside is that the motor will slightly ‘kick’ when switching between forward and backward. This can be done on both L298 and L9110.

  • pp (pwm, pwm): This interface uses two PWM signals to control the motor. The downside is that this will take up 2 PWM pins. Can be used on both L298 and L9110.

As you can see the choice for interface depends on the actual interface provided by the motor controller, and the number of (PWM) pins you have available on the MCU.

ddp (e.g. L298)

motor:
  left:
    name: left
    device: mirte
    type: ddp
    pins:
      d1: GP19
      d2: GP18
      p1: GP17     # pwm

dp (e.g. L298 or L9110)

motor:
  left:
    name: left
    device: mirte
    type: dp
    pins:
      d1: GP19
      p1: GP18      # pwm

pp (e.g. L298 or L9110)

motor:
  left:
    name: left
    device: mirte
    type: pp
    pins:
      p1: GP19       # pwm
      p2: GP18       # pwm

$ rosservice call /mirte/set_left_speed "speed: "

The motors will be defined separately. In this case there are two motors called ‘left_motor’ and ‘right_motor’, both controlled on the ‘mirte’ device defined above. The pins are set corresponding to the L9110s motor driver.

Warning

Please not that it is adviced to call the motors ‘left’ and ‘right’. You can chose your own names when you are only using these interfaces. In order to also get the ROS twist message (and steering in the web interface to work) you need to have the motors called ‘left’ and ‘right’.

Servo

servo:
  left:
    name: left
    device: mirte
    pins:
      pin: GP3

$ rosservice call /mirte/set_left_servo_angle "angle: 90"

Keypad

encoder:
  left:
    name: left
    device: mirte
    pins:
      pin: GP28     # analog input

As a topic (non-blocking):

$ rostopic echo /mirte/keypad/left

As a service (blocking):

$ rosservice call /mirte/get_keypad_left "{}"

OLED

oled:
  left:
    name: left
    device: mirte
    pins:
      scl: GP5
      sda: GP4

$ rosservice call /mirte/set_left_image "{type: 'text', value: 'hello mirte'}"
$ rosservice call /mirte/set_left_image "{type: 'image', value: 'mirte_logo'}"
$ rosservice call /mirte/set_left_image "{type: 'animation', value: 'eye'}"

Distance sensor

distance:
  left:
    name: left
    device: mirte
    pins:
      trigger: GP7
      echo: GP6

As a topic (non-blocking):

$ rostopic echo /mirte/distance/left

As a service (blocking):

$ rosservice call /mirte/get_distance_left "{}"

IR sensor

intensity:
  left:
    name: left
    device: mirte
    pins:
      digital: GP16
      analog: GP26     # analog input

As a topic (non-blocking):

$ rostopic echo /mirte/intensity/left
$ rostopic echo /mirte/intensity/left_digital

As a service (blocking):

$ rosservice call /mirte/get_intensity_left "{}"
$ rosservice call /mirte/get_intensity_left_digital "{}"

USB Camera

By default the robot assumes you have connected the supported USB cam (see basic hardware). Currently only a ROS interface is defined.

The camera image is published in three ways (using ROS image transport).

$ rostopic echo /webcam/image_raw
$ rostopic echo /webcam/image_raw/compressed
$ rostopic echo /webcam/image_raw/theora

Other USB Cameras

In case you have another USB webcam, you might need to change the parameters of the USB cam to reflect your webcam. This then needs to be changed in the launchfile:

$ v4l2-ctl --list-formats-ext
$ nano /home/mirte/mirte_ws/src/mirte_bringup/launch/minimal.launch