jasonmnemonic

000000	Officially Xerox
000001	SuperLAN-2U
000002	BBN (was internal usage only, no longer used)
000003	XEROX CORPORATION
000004	XEROX CORPORATION
000005	XEROX CORPORATION
000006	XEROX CORPORATION
000007	XEROX CORPORATION
000008	XEROX CORPORATION
000009	powerpipes?

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#!/bin/bash
cd /sys/kernel/config/usb_gadget/
mkdir -p pi4
cd pi4

echo 0x1d6b > idVendor # Linux Foundation
echo 0x0100 > idProduct # change to get Windows to rescan while testing
echo 0x0100 > bcdDevice # v1.0.0
echo 0x0200 > bcdUSB # USB2

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Preface

I owe my very rapid learning journey in the world of ConfigFs to several key sources which aren't necessarily relevant to this result, but I feel deserve a mention anyway.

• This really demystified configfs for me, and stopped me being afraid of it: http://events.linuxfoundation.org/sites/events/files/slides/USB%20Gadget%20Configfs%20API_0.pdf
• I borrowed heavily from this Mindstorms EV3 script: https://github.com/ev3dev/ev3-systemd/blob/ev3dev-jessie/scripts/ev3-usb.sh
• Desperately trawled this thread for answers: https://answers.microsoft.com/en-us/windows/forum/windows_10-networking-winpc/windows-10-vs-remote-ndis-ethernet-usbgadget-not/cb30520a-753c-4219-b908-ad3d45590447?auth=1
• This guide is handy: http://irq5.io/2016/12/22/raspberry-pi-zero-as-multiple-usb-gadgets/

jasonmnemonic

#!/bin/bash
# Set up a Raspberry Pi 4 as a USB-C Ethernet Gadget
# Based on:
#     - https://www.hardill.me.uk/wordpress/2019/11/02/pi4-usb-c-gadget/
#     - https://pastebin.com/VtAusEmf

if ! $(grep -q dtoverlay=dwc2 /boot/config.txt) ; then
    echo "Add the line dtoverlay=dwc2 to /boot/config.txt"
    exit
fi

jasonmnemonic

RTSP streaming from Raspberry PI

Introduction

This gist describes the necessary software installation steps for a Raspberry PI in order to enable the PI's camera to act as an external camera for the Dragonfly Java application. This gist shows, how to make a Raspberry PI an RTSP streaming server. The resulting feed can then be used as input for the Dragonfly Java app or the Accuware Dragonfly Demo - Calibration Mode server. The RTSP server on the Raspberry PI must be made publicly available, if calibration is a requirement.

Prerequisites

• Raspberry PI Zero W, 2, 3, 3b, 3b+, 4 with a Raspberry PI-Cam 5 MP or a [SainSmart Wide Angle Fish-Eye Cam](https://www.amazon.de/SainSmart-Fish-Eye-Camera-Raspberry-Arduino/dp/B00N1YJKFS/ref=asc_df_B00N1YJKFS/?tag=googshopde-21&linkCode=df0&hvadid=310638483583&hvpos=1o3&hvnetw=g&hvrand=12314684975119410116&hvpone=&hvptwo=&hvqmt=&hvdev=c&h

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Comparing node.js GPIO implementations

Here are two simple programs testing the performance of my rpio library against popular alternatives which use the /sys interface (with the number of npm stars indicated for a rough idea of popularity).

rpi-gpio (9 stars)

This test is based on an example on the rpi-gpio page.

As modules which uses /sys depend upon asynchronous behaviour they require callbacks to ensure that the next operation starts only when the previous one has completed.

jasonmnemonic

#include <stdio.h>
#include <string.h>
#include <fcntl.h>

#include <linux/i2c-dev.h>
// Terrible portability hack between arm-linux-gnueabihf-gcc on Mac OS X and native gcc on raspbian.
#ifndef I2C_M_RD
#include <linux/i2c.h>
#endif

jasonmnemonic

GCC compiler optimization for ARM-based systems

2017-03-03 fm4dd

The gcc compiler can optimize code by taking advantage of CPU specific features. Especially for ARM CPU's, this can have impact on application performance. ARM CPU's, even under the same architecture, could be implemented with different versions of floating point units (FPU). Utilizing full FPU potential improves performance of heavier operating systems such as full Linux distributions.

-mcpu, -march: Defining the CPU type and architecture

These flags can both be used to set the CPU type. Setting one or the other is sufficient.

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/**
  * Mosquitto C++ Wrapper
  * (C) 2017, Felix Niederwanger
  * MIT License
  */

#ifndef _MOSQUITTO_HPP_
#define _MOSQUITTO_HPP_

#include <string>

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
 * MCrypt API available online:
 * http://linux.die.net/man/3/mcrypt
 */
#include <mcrypt.h>