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BeagleBone SBC Cheatsheet

A comprehensive cheat sheet covering the BeagleBone Single Board Computer, including setup, GPIO, and common commands. This guide provides a quick reference for developers and hobbyists using BeagleBone for embedded projects.

Getting Started with BeagleBone

Initial Setup

Connecting to BeagleBone:

Connect BeagleBone to your computer via USB. It should appear as a network drive.

Accessing via SSH:

Use an SSH client (e.g., PuTTY, Terminal) to connect to the BeagleBone. Default IP address is 192.168.7.2. The default username is debian and the password is temppwd.

Updating the System:

After logging in, update the system using:

sudo apt update
sudo apt upgrade

Installing Essential Tools:

Install essential development tools:

sudo apt install git python3-pip build-essential

Configuring Network:

Edit /etc/network/interfaces to set up static IP address or other network configurations.

Basic Commands

pwd

Print working directory.

ls

List directory contents.

cd

Change directory.

mkdir

Create a new directory.

rm

Remove a file.

nano or vim

Text editors for file editing.

Boot Configuration

U-Boot:

BeagleBone uses U-Boot as its bootloader. Configuration files are located in /boot/uEnv.txt.

Kernel Configuration:

Kernel parameters can be modified via uEnv.txt. Changes require a reboot.

Device Tree Overlays:

Device tree overlays (.dtbo) are used to configure hardware peripherals. Enable overlays by adding lines to uEnv.txt.

Example Overlay Enable:

##Enable I2C1
dt overlay=BB-I2C1-00A0.dtbo

GPIO Programming

Accessing GPIO

GPIO Pins:

GPIO pins can be accessed via the command line or through programming languages like Python.

Using config-pin:

config-pin is a utility to configure pin modes.

sudo config-pin p9.12 gpio
sudo config-pin p9.12 out

Checking Pin State:

Read the value of the GPIO pin:

cat /sys/class/gpio/gpio60/value

Finding the GPIO Number:

Each pin has a GPIO number associated with it. Use the BeagleBone Black System Reference Manual to find the number.

Python GPIO Control

Installing py-gpio:

Install the py-gpio library for Python:

sudo pip3 install py-gpio

Python Code Example:

import gpio

pin = gpio.GPIO(60) # Example GPIO pin
pin.export()
pin.direction = 'out'
pin.value = 1  # Set pin high

Cleaning Up:

Always unexport the pin when done:

pin.unexport()

Alternative Library - Adafruit BBIO:

Another popular library is Adafruit_BBIO. Install with sudo pip3 install Adafruit_BBIO.

Device Tree Overlays for GPIO

Creating a Custom Overlay:

Create a device tree source (.dts) file. This defines the hardware configuration.

Compiling the Overlay:

Use the device tree compiler to create the .dtbo file:

dtc -O dtb -I dts -o my_overlay.dtbo my_overlay.dts

Example DTS file:

/dts-v1/;
/plugin/;

/{ 
	compatible = "ti,beaglebone-black";

	fragment@0 {
		target = <&am33xx_pinmux>;
		__overlay__ {
			pinctrl_bonnet_gpio: pinmux_bonnet_gpio {
				pinctrl-single,pins = <0x030 (PIN_OUTPUT_PULLUP | MUX_MODE7)>; /* P9_12, GPIO1_28 */
			};
		};
	};

	fragment@1 {
		target = <&ocp>;
		__overlay__ {
			bonnet_gpio {
				compatible = "gpio-leds";
			
gpios = <&gpio1 28 GPIO_ACTIVE_HIGH>;
				status = "okay";
			};
		};
	};
};

Networking

Configuring Network Interfaces

Listing Network Interfaces:

Use ifconfig or ip addr to list available network interfaces.

Editing /etc/network/interfaces:

Manually configure network interfaces by editing /etc/network/interfaces.

auto eth0
iface eth0 inet static
address 192.168.1.100
netmask 255.255.255.0
gateway 192.168.1.1
dns-nameservers 8.8.8.8 8.8.4.4

Using dhcpcd:

For dynamic IP configuration, ensure dhcpcd is running.

sudo systemctl enable dhcpcd
sudo systemctl start dhcpcd

Wireless Setup

Connecting to Wi-Fi:

Use iwconfig and wpa_supplicant to connect to Wi-Fi networks. First, identify wireless interface using iwconfig

Configuring wpa_supplicant:

Create/edit /etc/wpa_supplicant/wpa_supplicant.conf:

network={
	ssid="YourNetworkName"
	psk="YourWiFiPassword"
}

Bringing up the interface:

sudo ifconfig wlan0 up
sudo wpa_supplicant -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf
sudo dhclient wlan0

Firewall Configuration

Using iptables:

iptables is used for setting up firewall rules. Example: Allowing SSH traffic:

sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT

Saving Rules:

Save iptables rules using iptables-save.

Using ufw (Uncomplicated Firewall):

A more user-friendly firewall configuration tool:

sudo apt install ufw
sudo ufw enable
sudo ufw allow ssh

Peripherals and Hardware

I2C Communication

Enabling I2C:

Ensure I2C is enabled in uEnv.txt via device tree overlay. Example:

dt overlay=BB-I2C1-00A0.dtbo

Detecting I2C Devices:

Use i2cdetect to scan the I2C bus for connected devices:

sudo i2cdetect -y 1

Using i2cget and i2cset:

Read and write to I2C devices using i2cget and i2cset respectively.

UART Serial Communication

Accessing UART Ports:

UART ports are available as /dev/ttyO0, /dev/ttyO1, etc.

Using minicom:

Use minicom or screen to communicate over UART. First, install minicom:

sudo apt install minicom

Then, configure minicom:

sudo minicom -s

Example minicom Configuration:

Set serial device to /dev/ttyO1, baud rate to 115200, and disable hardware flow control.

PWM

Accessing PWM:

PWM functionality is available via device tree overlays. Enable PWM overlay in uEnv.txt.

PWM Control:

Control PWM parameters such as period and duty cycle via /sys/class/pwm/....

Example:

echo 1000000 > /sys/class/pwm/pwmchip0/pwm0/period
echo 500000 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle
echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable
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