Connection

ACADA Robotics • Documentation • ROS2RPI • Connection

⚠️ Checkpoint: Permissions

To ensure you’re in the i2c group, check the /etc/group file or run the following command: groups If you're not listed, you'll need to add yourself to the group using the following command: sudo usermod -aG i2c $USER Remember to log out and log back in for the group membership change to take effect.

The image depicts the physical connection between the ROS2RPi HAT and ROSRider cards using a standard QWIC cable. The ROSRider card’s additional QWIC port facilitates cascading configurations, enabling the expansion of the system with multiple ROSRider units or other compatible QWIC devices.

QWIIC cables are a popular choice for connecting various sensors and actuators to microcontrollers and other devices. They feature a 4-wire JST-SH connector on each end. One unique aspect of Qwiic cables is their asymmetrical orientation. One connector will typically be top-facing while the other is bottom-facing. This deliberate design choice helps with cable routing and prevents accidental misconnections, making it easier to create clean and organized setups.

⚠️ Checkpoint: Prerequisites

In order to send I2C commands from your host with Python, you need to install the python3-smbus2 library. For Ubuntu: sudo apt install python3-smbus2 If your Linux distribution does not have the python3-smbus2 package, use pip3 to install package locally: pip3 install smbus2

Sending one byte to I2C address 0x20 we can control all the peripherals on the device.

bit	function	mask	description
0	PSEL_3V3_A	0x01	Powers on I2C Bus Voltage-Level Translator A
1	PSEL_3V3_B	0x02	Powers on I2C Bus Voltage-Level Translator B
2	SERIAL_RX_ON	0x04	Connects the RPIs RX to debug port RX
3	SERIAL_TX_ON	0x08	Connects the RPIs TX to debug port TX
4	PSEL_LIDAR	0x10	LIDAR Power ON
5	LIDAR_TX_ON	0x20	Connects the RPIs RX to Lidars TX
6	LIDAR_PWM_ON	0x40	Connects RPIs GPIO19 to Lidars PWM input

> ROS2RPI_CONFIG

When operating the ROSRider card in conjunction with the ROS2RPI card on a Raspberry Pi platform, the driver provides the capability to transmit commands to the ROS2RPI card. This functionality is particularly valuable for controlling peripheral devices, such as lidar units, during the driver initialization sequence. If the ROSRider card is deployed independently (standalone configuration), set this parameter to 0.

Hat Command	Description
0x00	No Command
0x0F	ROSRider ON, Serial Routed to DEBUG
0x33	ROSRider ON, LIDAR ON, Serial Routed to LIDAR

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