Archive for category PC Tweakage

Raspberry Pi vs. Avahi

It turns out that the various Avahi daemons performing the magick between whatever.local names and dotted-quad 192.168.1.101 addresses for Raspberry Pi descend into gibbering madness when confronted with:

  • One name corresponding to multiple IP addresses
  • One IP address used for multiple MAC addresses
  • Multiple names for one IP address
  • Multiple names for one MAC address
  • Multiple IP addresses for one MAC address
  • Multiple MAC addresses for one IP address
  • Any and all combinations of the above at various times

The least of the confusion involved an incorrect IP address linked to a familiar name pulled from deep history by a baffled daemon doing the best it can with what it thinks it know. Despite what I concluded, rather early in the process, there’s no real error, other than what amounted to a self-inflicted fast-flux nameserver attack.

Anyhow, I devoted the better part of an afternoon to sorting out the mess, which involved labeling all the streaming radio players with their MAC addresses and rebooting them one-by-one to allow all the daemons time to recognize the current situation:

Raspberry Pi 3 - WiFi MAC address

Raspberry Pi 3 – WiFi MAC address

That label corresponds to the Pi 3’s on-board WiFi adapter.

For Pi 2 boxen, the MAC address travels with the WiFi adapter jammed into a USB port:

SunFounder WiFi Adapter - MAC address

SunFounder WiFi Adapter – MAC address

I didn’t label the (unused) Ethernet jacks, figuring I’d solve that problem after it trips me up.

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Raspberry Pi WiFi Adapters

One might be forgiven for thinking these two USB Wifi adapters are essentially identical:

USB Wifi adapters

USB Wifi adapters

Turns out the SunFounder RT5370 (on the top, with the stylin’ curved case) has better performance than the Wifi With Antenna (on the bottom, with full-frontal chunk goin’ on), by a not inconsiderable 5 to 10 dB. Boosting the received power level in the fringe areas of our house from -70 dBm to -63 dBm makes all the difference between not working and steady streaming.

The built-in WiFi antenna on a Raspberry Pi 3 ticks along 10 dB lower, with -80 dBm (10 pW!) at the receiver making for poor communication: a Pi 3 works perfectly within reasonable line-of-sight of the router (even through our wood floor) and wakes up blind in fringe areas. Hacking an external antenna probably helps, but definitely isn’t a net win compared to ten bucks worth of USB adapter.

The wavemon utility (it’s in the Raspbian repo) comes in handy for figuring that sort of thing.

There is, of course, no way to determine anything important about the adapters from their product descriptions, which are essentially identical, right down to the price. Neither have any product identification on their cases. The back of the package for the SunFounder gadget gives some specs, none of which may mean anything (clicky for more dots):

SunFounder RT5370 USB WiFi Adapter Specs

SunFounder RT5370 USB WiFi Adapter Specs

I ordered another SunFounder adapter, Just In Case it comes in handy, with the hope that both behave the same way.

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Xubuntu 16.04 LTS Bringup

Notes on updating my desktop Optiplex 980 from Xubuntu 14.04 LTS to 16.04 LTS, after being unable to compile OpenSCAD, Slic3r, and GNU Radio from source. Blowing three days on reconfiguration & tweakage after a clean install is the price one pays to get rid of a few years of cruft; the old version remains bootable and lootable on another partition, Just In Case.

Install:

  • nfs-common
  • xfce-goodies
  • hp2xx
  • xsane, xscanimage
  • kate (which hauls in a big hunk of wayland, alas)
  • digikam
  • chromium-browser
  • devilspie2
  • dropbox (from site)
  • remmina

Apply:

The hacks required to ensure NFS mounts happen before signing in seem to be obsolete. Given that systemd now controls everything, I have NFI how to proceed if that’s not the case.

The Xubuntu load progress display looks like it’s scaled up from 640×480.

There seems no way to disable on-screen notifications without deep hackery; some of the collateral damage involves the death of the volume control applet in the indicator panel thingy, so I didn’t try very hard.

The aforementioned volume control now fires up the Pulseaudio control dialog. That display explained why the audio came out of the 980’s crappy internal speaker, but switching it to the HDMI output produced only silence. After blowing away ~/.config/pulse and rebooting that sucker, it’s all good: Linux audio remains a slow-motion train wreck.

The initial sign-on dialog appears on the portrait monitor, minus rotation, because the dialog box follows the mouse pointer: the initial mouse position sits one pixel beyond the landscape monitor. Blind-type the password, whack Enter, and it’s all good.

FWIW, I’ve installed the XFCE flavor of Mint Linux on the laptops, but that’s basically Xubuntu with (some of) the ugly sanded off and really doesn’t buy much for somebody who pays no attention to eyecandy.

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Raspberry Pi Streaming Radio Player: Yet Another Cheap Wireless Keypad

One might think, just from looking, that this black wireless USB numeric keypad:

BonyTek Wireless USB Numeric Keypad

BonyTek Wireless USB Numeric Keypad

Was identical to the white keypads I already used on the streaming media players:

Wireless Keypad - colored labels

Wireless Keypad – colored labels

One would, of course, be wrong.

They both claim to be manufactured by “Creative Labs” with a 0x062a vendor ID, but with different model IDs:

  • White = 0x4101 “Wireless Keyboard/Mouse”
  • Black = 0x4182

Astonishingly, that model ID appears nowhere in Google’s search results, yet it actually works when plugged into my desktop PC.

The new model ID requires Yet Another Udev Rule in /etc/udev/rules.d/Streamer.rules:

ATTRS{idVendor}=="062a", ATTRS{idProduct}=="4182", ENV{ID_INPUT_KEYBOARD}=="1", SYMLINK+="input/keypad"

No big deal by now …

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Raspberry Pi: Forcing VNC Display Resolution

You can use VNC with a headless Raspberry Pi, but, absent a display with which to negotiate the screen resolution, X defaults something uselessly small: 720×480. To force a more reasonable resolution, edit /boot/config.txt and set the framebuffer size:

framebuffer_width=1920
framebuffer_height=1280

You can use a nonstandard resolutions, as with the 1920×1280 that fits neatly on my 2560×1440 landscape monitor, but getting too weird will surely bring its own reward. When you plug in a display, X will ought to negotiate as usual for the highest resolution the display can handle.

The System Configuration dialog has a “Resolution” button offering standard resolutions:

RPi display resolution configuration

RPi display resolution configuration

The shiny RPi Pixel UI bakes the RealVNC server directly into whatever handles the startup process these days, rendering all previous recommendations about forcing VNC resolutions inoperative. I found the trick of editing the config file on StackExchange after the usual flailing around.

Memo to Self: Remmina (the VNC client I use in XFCE on my desktop PC) doesn’t respond well to having the VNC server shut down while it’s connected. Fire up a command prompt, enter this:

sleep 10 ; sudo reboot

Then, quick like a bunny, disconnect the VNC session.

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Kinesis Freestyle2 Keyboard vs. Linux

My old Microsoft Comfort Curve keyboard having gotten on in years, I picked up a Kinesis Freestyle2 (KB800B for PC) split keyboard:

Kinesis Freestyle2 - desk layout

Kinesis Freestyle2 – desk layout

The little hinged dingus (“Pivot Tether”) between the halves (“Keying Modules”) has two posts that pop into into sockets on the back of the halves and are retained by the two sliding latches. The cord connecting the halves allows 9 inches of separation; I don’t need that much, but more than zero seemed about right.

Kinesis also sells various staggeringly expensive (IMO) doodads that attach to the back of the keyboard to “tent” the middle upward with varying degrees of refinement. None of the doodads offer to raise the back of the keyboard, which I vastly prefer to the current flat or reverse-tilted recommendations.

The keyboard & trackballs rest on a homebrew shelf that slides out from where the desk used to have a center drawer, which puts the keyboard slightly above elbow height (heck, slightly above thigh height), whereupon tilting the keyboard puts the keys exactly where they should be. I bandsawed some wood into vaguely triangular sticks, topped them with foam sheets, and tinkered for best tilt. Works for me, anyhow.

The Compatibility section of the Freestyle2 User Manual describes the “special driverless hot keys”: Most will also work with Linux. Four of them do not work, to the extent that they don’t even send key codes to exv. Some searching suggests this is an intractable problem, for reasons that make no sense to me. Their HID Usage Codes, whatever that might mean:

Kinesis Freestyle2 - inert key codes

Kinesis Freestyle2 – inert key codes

That’s only a minor inconvenience; I prefer a physical calculator and don’t spend much of my life listening to anything through the headphones.

For whatever it’s worth, the scroll ring on the most recent warranty replacement Kensington Expert “Mouse” (I think it’s the third) has worked flawlessly for years; they seem to have fixed the sudden death syndrome.

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Epson R380 Printer: Resetting the Waste Ink Counter Again

The Epson R380 printer never gets turned off, so it rarely has a chance to complain. After a powerdown due to refreshing the UPS batteries, it lit up with the dreaded “Service required. Visit your friendly Epson repair center” message that indicates you should just throw the printer out, because replacing the internal ink absorber mats / draining the internal tank is, mmm, economically infeasible when you pay somebody else to do it.

Having done this before, though, it’s almost easy…

  • Pop a PC with a Windows partition off the to-be-recycled stack
  • Boot System Rescue CD
  • Back up the partition to a junk hard drive, just for practice
  • Copy the subdirectory of sketchy utilities to the Windows drive
  • Boot Windows (with no network connection)
  • Run sketchy utility to reset the ink counter
  • Boot SRC, restore partition
  • Return hard drive & PC to their respective piles
  • Declare victory and move on

This time, a sketchy utility that resembled the Official Epson Reset Program actually reset something and the printer started up normally. As before, however, the saved MBR didn’t match the on-disk MBR, suggesting that either I don’t understand how to save / restore the MBR or that something once again meddled with the MBR in between the backup and the restore.

I’ve emptied the waste ink tank maybe three times since the last reset: plenty of ink down the drain. Fortunately, I loves me some good continuous-flow ink supply action…

Sheesh & similar remarks.

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