Quanser QBot 2e

The Quanser QBot 2e is an Unmanned Ground Vehicle (UGV) built and sold by Quanser Inc. The Quanser QBot 2e is based around a Raspberry Pi 3 B+, which has a quad-core 1.4 GHz ARM Cortex-A53 processor with 1 GB RAM running Raspbian. The QUARC Target associated with the Quanser QBot 2e is the QUARC Linux Raspberry Pi 3 Target. The Quanser QBot 2e HIL card may only be used with QUARC when this target is selected. The following characteristics are of particular interest when using the Quanser QBot 2e with QUARC:

• 28 reconfigurable digital I/O, 3.3V with some pre-configured as follows:
• 2 PWM output channels, 3.3V
• 1 general purpose +3.3V serial port*
• 1 general purpose SPI port*
• 1 general purpose I2C port*
• Integrated with MATLAB/Simulink/Simulink Coder via Quanser QUARC

* Communications channels are accessed through the Stream API blocks, see Serial protocol, SPI protocol and I2C protocol.

The Quanser QBot 2e also supports specialized quantities such as the following:

• Battery voltage measurement
• Cliff sensors (right, central and left)
• Wheel drop sensors (right and left)
• Wheel encoders (right and left)
• Bumper sensors (left, central and right)
• Three-axis gyroscope providing angular velocity measurements
• Three user-accessible buttons
• Two multicolour LEDs
• Predefined or custom sounds
• Various user-accessible power sources (3.3V, 5V and 12V)
• Motor command measurement (right and left)
• Motor current measurements (right and left)
• Overcurrent detection
• Charger state
• Docking IR sensors (right, central and left, both near and far)

The QUARC driver name for this card is qbot2e.

To select the Quanser QBot 2e HIL board, select the QUARC qbot2e board type from the drop-down list on the Main tab of the HIL Initialize block.

Communications

The communications ports provided on the Quanser QBot 2e board can be utilized through the QUARC Communications blockset and the Quanser Stream API (see QUARC Communications Protocols).

For SPI communications, a sample URI for communications would be:

spi://localhost:0?baud='1000000',phase='off',lsb='off',frame='0'

where the frame option selects the SPI CE line to frame the SPI bus transaction (0 or 1). Note that the SPI port must be enabled using the raspi-config utility for SPI communications to be used. Once the SPI port is enabled, the corresponding digital I/O (pins 19, 21, 23, 24 and 26) will no longer be available as digital I/O.

SPI can also be enabled via the file by setting spi=on in the Device Tree Overlay parameters. For example:

dtparam=spi=on

After changing , reboot the Raspberry Pi for the changes to take effect.

For I2C communications, a sample URI for communications would be:

i2c://localhost:0?baud='400000',address=0x69

where the address option specifies the I2C slave address. Note that the I2C port must be enabled using the raspi-config utility for I2C communications to be used. Once the I2C port is enabled, the corresponding digital I/O (pins 3 and 5) will no longer be available as digital I/O.

To set the baud rate for the I2C, the file must be edited and the Raspbery Pi rebooted. For example, to enable I2C and set the I2C baud rate to 400000 baud, change the Device Tree Overlay parameters to:

dtparam=i2c_arm=on,i2c_arm_baudrate=400000

After changing , reboot the Raspberry Pi for the changes to take effect.

For serial communications, a sample URI for communications would be:

serial://localhost:1?baud='115200',word='8',parity='none',stop='1'

Configuring the Quanser QBot 2e to support serial communications is a bit more involved. First, use the raspi-config utility to disable the serial port use by the kernel console. Then edit the so that:

enable_uart=1

Also add the line:

dtoverlay=pi3-disable-bt

in order to disable bluetooth, which makes use of the UART otherwise (see Pi Zero W WiFi interference with TTY). Alternatively, to maintain bluetooth and use the UART, use the lines:

dtoverlay=pi3-miniuart.txt

core_freq=250

Refer to this Raspberry Pi forum topic for details.

After changing , reboot the Raspberry Pi for the changes to take effect. Use the gpio readall command to confirm that the TxD and RxD pins for the UART are in ALT0 mode. The serial port is /dev/ttyAMA0.

Clocks

There are currently no configuration options for the Quanser QBot 2e clocks.

Analog Inputs

The Quanser QBot 2e supports 6 analog inputs. Hence, analog input channel numbers range from 0 to 5. The full suite of analog inputs are enumerated in the table below:

¹ For the non-linear relationship between the raw voltage from a cliff sensor to actual distance, refer to the Sharp Analog Output Type Distance Measuring Sensor Data Sheet.

Analog Outputs

The Quanser QBot 2e card does not support analog outputs.

Digital Inputs

The Quanser QBot 2e supports 59 digital inputs. The first 28 channels are user-accessible reconfigurable digital I/O lines that may be used as digital inputs. Channels 0 and 1, however, are reserved for a HAT EEPROM I2C interface. A digital I/O line cannot be used as an input and output at the same time. Nor can it be used for communications (SPI, I2C or UART) or PWM at the same time. The full suite of digital inputs are enumerated in the following table:

Since the digital I/O lines may be individually programmed as inputs or outputs on the Quanser QBot 2e, all channels which will be used for digital inputs should be configured on the HIL Initialize block's Digital Inputs tab. Set the Digital input channels field to all the digital I/O channels that will be used as digital inputs on the board for the current diagram. For example, enter 2:4 to designate channels 2 through 4 as digital inputs. Specify [2, 4, 5] to indicate that channels 2, 4 and 5 are to be configured as digital inputs.

Note that the dock IR signals may oscillate when the IR signal is detected. This oscillation is a function of the way the docking IR signals work.

Digital Outputs

The Quanser QBot 2e supports 36 digital outputs. The first 28 channels are user-accessible reconfigurable digital I/O lines that may be used as digital outputs. Channels 0 and 1, however, are reserved for a HAT EEPROM I2C interface. A digital I/O line cannot be used as an input and output at the same time. Nor can it be used for communications (SPI, I2C or UART) or PWM at the same time.

Since the digital I/O lines may be individually programmed as inputs or outputs on the Quanser QBot 2e, all the channels which will be used for digital outputs should be configured on the HIL Initialize block's Digital Outputs tab. Set the Digital output channels field to all the bidirectional digital I/O channels that will be used as digital outputs on the board for the current diagram. For example, enter 2:4 to designate channels 2 through 4 as digital outputs. Specify [2, 4, 5] to indicate that channels 2, 4 and 5 are to be configured as digital outputs.

To set the digital output values when the model is loaded or unloaded, set the Initial digital outputs and Final digital outputs to the desired values respectively. If the vectors specified in these fields are shorter than the channel vector, the value of the last element in the vector will be used for the rest of the channels. Hence, a scalar value will apply to all channels specified in the Digital output channels field.

The full suite of digital outputs are enumerated in the following table:

¹ Disabling the 12V/5A power will power down the Raspbery Pi 3 processor. The chassis will have to be turned off and back on in order to restore power and wireless communications with the Pi 3 target.

Encoder Inputs

The Quanser QBot 2e supports two encoder inputs. The encoder channels are enumerated in the table below:

In order to set the encoder counters to a particular count, the encoder inputs must be configured on the HIL Initialize block's Encoder Inputs tab. Set the Encoder input channels field to all the encoder channels that will be used on the board for the current diagram. For example, enter 0:1 to indicate channels 0 through 1 are used as encoder inputs.

PWM Outputs

The Quanser QBot 2e driver supports up to 2 PWM output channels. Hence, PWM output channels range from 0 to 1. Each PWM channel is completely independent and can have its own duty cycle and frequency.

Before the PWM channels may be used, they must be configured in the file and in the board-specific options. The file must be edited with root privileges. For example, to use the vi editor, enter the command:

sudo vi /boot/config.txt

in a terminal window.

The lines which must be added to the file depend on the number of PWM channels desired, and the pins to which they are assigned. The following table documents the lines that must be added to the file for each combination of options:

In order to configure the PWM mode or frequency, or to set the value of the PWM outputs when the model is loaded or unloaded, the PWM outputs must be configured on the HIL Initialize block's PWM Outputs tab. Set the PWM output channels field to all the PWM output channels that will be used on the board for the current diagram. For example, enter 0:1 to indicate channels 0 and 1. Specify 1 to indicate channel 1 alone.

The PWM outputs are generic PWM outputs that are capable of producing the standard analog ESC protocols, namely standard PWM (1000us to 2000us), Oneshot125 (125us to 250us), Oneshot42 (42us to 84us) and Multishot (5us to 25us). They may also be used to drive R/C servos.

The PWM parameters for each of these protocols are tabulated below:

The PWM outputs are not restricted to these parameter values as they are generic PWM outputs. The maximum output frequency is 50 MHz. The number of bits of resolution decreases with increasing PWM output frequency.

Set the PWM output frequency (a.k.a., pulse rate) in the "Frequencies in Hz or duty cycle" field. The PWM output mode is typically set to duty cycle mode (0) or time mode (4) when driving ESCs or R/C servos. Set the Initial PWM outputs and Final PWM outputs fields to the desired initial and final output values respectively. The interpretation of these output values depends on the PWM mode selected. If the vectors specified in these fields are shorter than the channel vector, the value of the last element in the vector will be used for the rest of the channels. Hence, a scalar value will apply to all channels specified in the PWM output channels field.

Other Inputs

The Quanser QBot 2e supports eight other input channels. The other input channels are defined as follows:

¹ The charger state takes on discrete values depending on whether the docking station is being used and whether the battery is fully charged. The following table shows the charger state values:

As a reference, the generic table for the Other channels for any HIL Data Acquisition Card is reproduced below. SI units are used.

Other Outputs

The Quanser QBot 2e supports four other output channels, allowing the wheel velocities to be controlled and sounds to be generated. Refer to the table below for a list of the channels:

Interrupts

The Quanser QBot 2e card, or its driver, does not support any interrupt sources.

Watchdog

The Quanser QBot 2e card does not support a watchdog timer.

Board-Specific Options

The Quanser QBot 2e has a number of board-specific options to control specialized functionality of the board. These options configure the PWM.

pwm0_en

This option is a boolean value that enable or disables PWM 0. If PWM 0 is disabled then the PWM pin may be used as a regular digital I/O. Valid values are 0, 1, false, true, off, on, no or yes.

pwm1_en

This option is a boolean value that enable or disables PWM 1. If PWM 1 is disabled then the PWM pin may be used as a regular digital I/O. Valid values are 0, 1, false, true, off, on, no or yes.

pwm0_pin

This option determines which pin will be used for PWM 0. Valid values are 12 or 18 corresponding to GPIO 12 or GPIO 18 respectively.

pwm1_pin

This option determines which pin will be used for PWM 1. Valid values are 13 or 19 corresponding to GPIO 13 or GPIO 19 respectively.

Properties

The Quanser QBot 2e driver currently supports the following read-only properties:

The following properties may be both read and written:

Connectors

The Quanser QBot 2e board has one connector for expansion I/O. The pinouts for this connector are listed below. Note that all pins are 3.3V and are not 5V tolerant unless marked otherwise. Exceeding these voltages may damage the board!

Raspberry Pi GPIO Connector

Legend

Targets

See Also

• QUARC Linux Pi 3 Target

Copyright ©2024 Quanser Inc. This page was generated 2024-10-17. Submit feedback to Quanser about this page.

Link to this page.