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Showing posts with the label hardware

Troubleshoot USB-Printer Connected to Router

I had complained about a flood of error messages being continuously printed out every time a print job was sent to the USB-printer attached to my Asus AC56U router with merlin-378.55_beta1. Yesterday, after I had reverted to the official asuswrt firmware to troubleshoot the printer-sharing feature, I used nmap on my laptop to see the open common ports on the clients on my network:


Code: # nmap -T4 -F 192.168.1.0-2 The router displayed two ports related to the printer service:


Code: 192.168.1.1 Host is up (0.0065s latency). Not shown: 94 closed ports PORT STATE SERVICE 53/tcp open domain 80/tcp open http 139/tcp open netbios-ssn 445/tcp open microsoft-ds 515/tcp open printer 9100/tcp open jetdirect Anyway, long story short, I had been using the socket://192.168.1.1:9100 path to the printer; changing the configuration on my laptop (CUPS-server) to point to lpd://192.168.1.1:515/AUTO finally resulted in SUCCESS!

Linux: Keyboard-Mapping Control

Remapping Keys Given the variations in physical keyboard layouts across personal computers from different manufacturers, the potential for a configured key to be mapped differently than expected or even to be missing on some keyboards creates the need for System Administrators to be able to remedy this problem by remapping the desired functions to the available key(s) of their choosing.  Luckily, there are a number of powerful tools available for the Linux OS, some of which will be outlined in this note with a few usage examples and scenarios.

xevxmodmapshowkeyloadkeys
How to Map the Super key to Search key The Samsung Chromebook doesn't have a Super key, or "Windows" key, on its keyboard; as a result, the Super key, which is usually mapped to it by default, is missing from the keyboard and the user is missing a useful function from certain applications.
    In order to provide the user with a convenient shortcut on their keyboard, first we need to find find out some mo…

How to Connect a TI Graphing Calculator to a Linux PC

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This post will document how to install a linking program for a TI-83+ on a Fedora18-x86_64 laptop. The purpose of the program is to be able to connect your Graphing Calculator via a USB TI Connectivity Cable, in order to transfer data to/from your Graphing Calculator. I should mention that I am not in any way affiliated with the developers of any of these programs, and I take no credit for any of its development; this is merely meant to help those who are struggling to install this valuable software on their computers.
What you will NeedTI Graphing Calculator (obviously)Connectivity Cable (GraphLink cable)TILP2 (TI Linking Program)TILIBS (the library files for the program)libglade2-dev, libusbx-devel (development files for certain libraries on your Fedora/Linux computer) Installation I will assume that you already have the calculator and the necessary cables for the remainder of this procedure, and so we will proceed to download the necessary files from ticalc.org. That's a g…

Raspberry Pi2 Serial-to-USB Connection on Linux

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Raspi2 Serial In order to connect the raspberry pi 2 to a PC running Linux one must first obtain a "USB-to-TTL" Serial Debugging cable; certain precautions need to be made when selecting the appropriate cable:
it should use 3.3V logic levels to avoid frying your boardSince GPIO headers are not adjacent, it should have separated cables for each pin


















https://www.raspberrypi.org/documentation/usage/gpio-plus-and-raspi2/README.md
http://elinux.org/RPi_Serial_Connection

Samsung Printer Scanner on Linux

Once again, I've been made to feel as just another outcast in the information age of script-kiddies and spreadsheet warriors; yet another instance of a corporation neglecting Linux users with lacking software support and drivers for their devices.  As in most other cases, the linux community provides their own workaround in this instance as well; namely, the SANE (Scanner Access Now Easy) backend and libraries for the Samsung CLX-3185 Multifunction Printer/Scanner device.  The Samsung support website claims to offer a "Universal Linux Driver", but that's just a smokescreen created by the ineffective binaries and poorly constructed installation scripts from Samsung.  Notwithstanding, the SANE backend implementation isn't perfect  either--as there are still issues with certain System setups, USB 3.0, or simply non-supported devices--but it's far better integrated into the Linux ecosystem. 

It can be very frustrating not being able to complete an important task …

CPU Fan Control on ThinkPad Laptop

I have a Lenovo ThinkPad laptop that occasionally displays error messages about "Hardware events/THERMAL EVENTS" during times of high CPU usage.  This is a scary set of messages in the journal logs that could prophecy a short life span of the CPU if neglected; at times I've suspected that it may have been the culprit of system crashes, though, I won't go into further details on that here.

It's worth noting that the performance improves and error messages subside after one disassembles the laptop and cleans out the heat sink; maybe even properly applies a fresh coat of thermal compound on it.  This improvement, however, never lasts too long as the dust accumulates within the heatsink area again.

I can recall reading anecdotal evidence of this problem from other ThinkPad owners on the Lenovo forums and other places when I first came across these scary messages on my system.  Those owners running Linux on their laptops offered explanations about the poor air fl…

Power Management and Performance in Enteprise Linux (EL7)

As with most things in Linux, there are an array of different tools and options available when dealing with the performance and power consumption of hardware components. Nevertheless, certain standard or even non-standard defaults always emerge, either distribution-specific or -agnostic. While a greater number of available tools provides greater control and more possible solutions, it also brings with it the possibility of greater potential for confusion and unclear incompatibilities. One such confusion arose when I noticed the inconsistency in my CPU frequency preference across reboots. I was used to using the cpupower utility from the kernel-utils package; however, options in the configuration file in /etc/sysconfig/cpupower had no effect on the system during the boot up process. It turns out that RHEL7 and, by extension, Centos EL7 use the tuned utility by default for performance tuning. As a result, according to a forum post in the Centos forum, ...that service conflicts …

Ricoh SD-Card Reader and Linux

The linux kernel adds the benefit of making firmware drivers available for a large number of widely-used hardware devices and components. This provides great convenience and ensures portability and sane defaults across the various OS distributions. The open-source nature of the Linux kernel, however, relies on the hardware manufacturers to make the firmware and/or drivers available to the Linux community; a process that can be frustratingly slow at times, depending on the hardware manufacturer. Furthermore, once the driver is included in the kernel, it falls on the various OS distributions to make the kernel or a patch to the kernel available for the users to install.
The functionality of rarely-used hardware like a multimedia card reader (SD-card reader) are often overlooked by users until the day when they try to use the device. Usually, the kernel will load the necessary modules for the device to function properly during the boot-up process. Though, if an SD-card is not …