Pushing VLAN tags through unmanaged switches

2014-03-13 19.47.41

Kenneth Finnegan writes:

This year, I was designated as the computer network zonie, so it’s my job to make sure that there’s IP connectivity between all the major sites in the network. This involves building a computer network that includes a couple Internet hand-off points, multiple routers, several medium-range (2-5km) microwave links, QoS enforcement for a few hundred devices to support VoIP and streaming video while sharing a 15Mbps Internet uplink, a couple 802.1Q VLAN trunks, etc.
Needless to say, we are building a network beyond the budget we’re being given, so duct tape and Linksys devices are being applied liberally throughout this project.

One problem we’ve encountered this year is that we need a few network devices to be on the same layer two network while being two miles apart. These two sites don’t have line of sight, so we’re using two microwave links to bounce off a third site between them, while these links also need to carry a few other L2 domains. A perfect application for VLAN tagging.

Bus Pirate Demo Board 1: 1 Wire devices

2014-03-09-11.47.41

Andrew Rohne writes:

In learning how to use the Bus Pirate, I started with the one-wire area of the demo board.
First off, important notes:
-I’m using the v 3.8 Bus Pirate. The pinout is different than some of the others.
-I’m using a Sparkfun Bus Pirate cable.

The first part of this is based on using the DS2431 1,024 bit (1 kilobit?) EEPROM. The second part is using the DS1822 temperature sensor.

New Energia version available

Energia

The Energia team announces the availability of version 0101E0012.  We wrote about it previously:

Energia is an open-source electronics prototyping platform started by Robert Wessels in January of 2012 with the goal to bring the Wiring and Arduino framework to the Texas Instruments MSP430 based LaunchPad. Energia uses the mspgcc compiler by Peter Bigot and is based on the Wiring and Arduino framework. Energia includes an integrated development environment (IDE) that is based on Processing.

HP LaserJet 4000 front panel with Bus Pirate

hp4000_proto

kbiva has posted a detailed tutorial on how to connect and control HP LaserJet 4000 front panel with Bus Pirate v3.6:

Connected 7 lines from printer front panel to corresponding Bus Pirate pins.
SPI parameters set in Bus Pirate:
-SPI speed is 1Mhz
-Clock polarity: Idle low
-Output clock edge: Active to idle
-Input sample phase: Middle
CS: /CS
-Output type: Normal (H=3.3V, L=GND)

Protocol description – sending 2 bytes and receiving 2 bytes
Command set is HD44780 compatible.

Via the contact form.  Thanks Kevin!

Check out the video after the break.

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors. Continue reading “HP LaserJet 4000 front panel with Bus Pirate”

Free PCB coupon via Facebook to 2 random commenters

probecable-yellow

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Tutorial: solid state drives and Linux


Solid state drives (SSD) are gaining in popularity, particularly as components costs and machine form factors continue to shrink. In this article from Linux Journal online magazine, Brian Trapp gives an in depth presentation on the current state of SSD’s and their advantages and disadvantages in various Linux related operations.

Meet the amazing China power outlet

By ian

Traveling abroad you’ll likely encounter many different outlets. While most of our stuff uses an adapter that will take any local power supply from 100volts to 240volts, the plug shapes are still different. Usually you buy a way over-priced adapter for a specific region before heading out.

Not in China! In Shenzhen most wall outlets and power strips use this amazing universal socket. It accepts US/Japan/China style blades, Australia’s slanty blades, European pins, UK/Hong Kong bulky crazy slugs, and probably some others. I like to think this evolved because appliances made by Chinese OEMs have whatever plug a foreign company ordered and the Chinese adopted this socket to accommodate the general randomness of the stuff available.

This particular outlet is in a “tower” power strip currently popular in Huaqiangbei. It also has 4 USB ports capable of 2.1A (so it claims…) for charging as well. A tower with 16 plugs ran me 60RMB (~$10USD).

P.S. Local voltage is 220AC/50Hz in Shenzhen, China.

Via Hacker Camp Shenzhen mini-site: Meet the amazing China power outlet

Week in (p)review March 21, 2014

microMsg.1394359546454-W6001

Here’s a summary of major developments over the last week. Free PCB Friday is coming up soon.

Coming up:

  • Free PCBs via Facebook on Friday
  • App notes on the weekend
  • Free PCB Sunday
  • Free PCBs via Twitter on Tuesday
  • Weekly roundup and preview every Friday

BJT in reverse avalanche mode

Flasher

Kerry Wong writes:

Transistors operating in their avalanche regions are often used to generate fast rise pulses (see avalanche pulse generator using 2N3904). Many transistors can also avalanche when the connections to collector and emitter are reversed. When operating in reverse avalanche region, these transistors are sometimes referred to as negistors.
Because the asymmetry and doping differences between the base-emitter and base-collector junctions, the avalanche voltages for reversely connected BTJs are usually magnitudes lower than their normal avalanche voltages. Here, I decided to test a few different transistors and see at what voltages the reverse avalanche occur.

The circuit I used is a simple LED flasher, similar to what was described here. As with any circuit that exhibits negative differential resistance, the principle of operation is quite simple. The capacitor is charged via a current limiting resistor…

µ-Wire: USB on ATtiny10 controlling a WS2812 LED

u-wire-test

cpldcpu writes:

I tried to push the ATtiny10 to its limits and succeeded – I implemented a seriously gutted version of V-USB on an SOT23 ATtiny10 with just 1kb flash and 32b of RAM. It implements a subset of the little-wire protocol to control a single WS2812 LED.

I am currently also working on size optimized hardware. Already got it down to 0.3″x0.4″. I wonder why OSH Park is still putting up with me ;)

Via the project log forum.

Shenzhen workshop hackerspace passport stamps

By ian

Everyone attending Hacker Camp Shenzhen will get a Chinese-style hackerspace passport made by Seeed Studio. We created two stamps for the camp. One is for the market tour, the other for the soldering workshop. Hold onto the passports, there will be many more opportunities to get stamps at the Shenzhen Maker Faire following the camp.

Via Hacker Camp Shenzhen mini-site: Shenzhen workshop hackerspace passport stamps

Bus Pirate v3.6 back in stock

Bus Pirate v3.6 universal serial interface is back in stock at Seeed Studio. This is the updated v3.6 in a standard PCB footprint. You can get a simple laser-cut acrylic protector for this board for only 3 bucks.

Bus Pirate is a hacking multi-tool that has the capability to interface with most IC bus protocols used in the electronics industry today.

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Nutaq’s SDR project idea contest


Tristan Martin from Nutaq writes to inform us of their academic contest (US only) for winning a PicoSDR kit with MIMO OFDM ref design (FPGA), it supports GNU Radio (GigE and PCIe).

“You can submit with an existing (ongoing) project, it doesn’t have to be a “new” project. We do NOT get involved in the project execution or ask for any actual results. The contest is just about giving away an SDR platform based on submitted “project ideas”. Points are attributed for the use of GNU Radio.”

Visit Nutaq’s contest page for details or to register. Deadline is March 31, 2014.

Piezoelectric crystal speaker build

This video by RimstarOrg demonstrates how to build a Piezoelectric crystal speaker:

I make a loud speaker for a clock radio using a piezoelectric crystal. Actually I experiment with a variety of piezo crystals. That includes a piezoelectric igniter crystal from a BBQ lighter and a homemade/DIY rochelle salt piezoelectric crystal. I also try out a piezo buzzer from Radio Shack and also a crystal earpiece normally used with a crystal radio. To increase the voltage coming from the radio I first try stepping it up using a doorbell transformer and then I use a microwave oven transformer.

Via Hacked Gadgets.

DIY digital desk clock with temperature display -part 1

digital-desk-clock-front-operational

A digital desk clock with temperature display feature by Electro-Labs:

The brain of the circuit is a Microchip PIC18F252 microcontroller. It acquires precise time information from DS1307 real time clock via I2C interface and displays it on four digit 38 mm seven-segment display with the help of MAX7219CNG display driver. The temperature data is read by the on-chip ADC module of the microcontroller from LM335 temperature sensor which outputs 10mV per kelvin degree linearly. The temperature data is also displayed periodically.

The PIC microcontroller and the peripheral ICs mentioned above needs 5V regulated supply to operate. The step-down converter in the power section of the circuit, LM2574N-5.0, converts 12VDC input voltage to 5VDC and lets to draw 500mA without any significant heating problem.
There are two LEDs on the board indicates power and functional status and the buttons let the user adjust the time and display the temperature manually.

Hacked GTP USB LITE pic programmer

2014-03-18_2139

cmardone of Valpoder wrote an article on hacking the GTP USB LITE usb pic programmer, we wrote about it previously:

GTP USB LITE is a pic programmer based on the pic18F2550 disgned by SISPIC from spain
A lot of people built this circuit , and it became obsolete..
The firmware has several limitations(ex: driver only for xp) so i decided to hack firmware…

GOOD NEWS
-Now it runs in windows, linux and mac .
-firmware is opensource..

Via the forum.

Video tutorial: OFDM packet transceivers with GNU radio


Orthogonal frequency-division multiplexing or OFDM is a method of encoding digital data on multiple carrier frequencies.

At this presentation from them recent FOSDEM 2014 conference in Brussels, Martin Braun explained the use of GNU Radio software and an SDR transceiver to explore OFDM block basics, how to set up links between nodes and how to start working on MACs.

Martin explains, “GNU Radio is a powerful tool for signal processing of any kind. It is very much suited for setting up any kind of communication link. In this tutorial, we will discuss how to set up a PHY that can be attached to an application and MAC layer in order to experiment with arbitrarily configured wireless networks.”