David Nichols made this awesome wireless twitter display by combining a hacked Asus WL-520gU wireless router with a Sparkfun serial-enabled LCD display.  The router is running the same OpenWrt distribution I used for my Wifi Radio project, plus a USB thumbdrive that provides some additional flash storage space.  I really like the custom laser cut base that holds the LCD display and the router!

For more pics and info, check out David’s flickr set for the project.

via Make: Online – Tweetster – Wireless tweets display

Leave a comment below and let me know how your project is coming along.  Even if you’re not building a Wifi Radio but used my firmware or tutorials as a starting point (a great example is the Tweet-a-Watt), I’d love to hear from you.

If you have photos of your project, you can share them with the world by adding them to the Asus Wireless Router Hacks photo pool on flickr.

www.flickr.com More in Asus Wireless Router Hacks pool

I added a link to possible sources for as many parts as I could.  However, there were a few things I scrounged from local surplus electronics stores and couldn’t easily find a good equivalent online.  I’m not expecting everyone to copy my design exactly (not everyone has a woodworking shop at their disposal), so use these numbers as a rough estimate only.

If you shop around you should be able to beat the listed prices on many items, so I see this as sort of a worst case scenario.

To flash the wireless router and create a minimal radio (with no user interface), you will need:

• Asus WL-520gU wireless router – currently $34.99 with MiR
• SYBA SD-CM-UAUD USB Stereo Audio Adapter – $7.99
• FTDI USB TTL-232 3.3V serial adapter cable – $20
• 0.1″ Break-away Header Strip – $2.50

Total: $65.48

To make the LCD display and tuner interface, you’ll also need:

• USBtinyISP AVR programmer – $22
• 16×2 Character LCD (5V) – $13.95
• ATmega168 microcontroller – $4.11
• 28-pin socket – $1.50
  
• 16MHz crystal – $1.50
• 2 x 22pF capacitors – $0.25 ea.
• Contrast trimpot, 1k (or similar) – ~$0.75
• Tuner potentiometer, 10k – $1.40
• Reset microswitch – $0.35
• Serial connector (cut an old CD-ROM audio cable in half) – $0
  
• Protoboard – $5
• Some hookup wire - $0
  
• 0.1uF bypass cap and a few resistors (10Ohm and 1K) - around $1 at any decent electronics store

Total: $52.06

(This is on the high end, the interface can certainly be built for less by using scrounged/surplus components.)

To make the finished radio, add:

• Volume and tune knobs – ~$2 @ HSC
• Cool tuner knob – $8.55
• 5V/12V power supply brick – $10 @ Weird Stuff
• 5-pin mini-DIN power connector – ~$3 @ HSC
• Power switch – ~$1 @ HSC
• Cheap set of PC speakers (gutted for the speakers and amplifier) – $5 @ Weird Stuff

Total: $29.55

Oh yeah, and I almost forgot…

• An awesome friend named Tony with a full woodworking shop in his garage who will make you a killer wooden enclosure for free – $priceless

Grand total (excluding the box) – $147.09

If you take out the cost of the development tools, namely the FTDI cable and the USBtinyISP, the total comes out to $105 (without the box).

By scrounging materials and using parts from your junkbox you should be able to reduce that figure even more, but obviously the grand total hinges on what kind of enclosure you use.  Not everyone has a friend with serious woodworking skills willing to donate time and materials, but use this as an excuse to get creative.

I wanted a box that showcased the time and effort that I spent on the electronics inside, but that doesn’t mean an old boombox from the Salvation Army couldn’t work just as well.

When I first started this project, my goal was to keep the total parts cost under $100.  On paper, it looks like I came pretty close to that, thanks to the donated box and excluding the reusable development tools like the FTDI cable and AVR programmer.  To be honest, I probably spent twice that amount on spare power supplies, extra knobs, a second router to bring to NOTACON, and a bunch of other stuff that I didn’t end up using in the final project.  But I’m pretty ok with that.  I think this just highlights the fact that:

If you just want a Wifi Radio, it will always be cheaper to buy one off the shelf. But if you make your own, it will be infinitely more rewarding.

It certainly has been for me. 

Newegg.com is currently offering the Asus WL-520gU for $34.99 after rebate. This is the lowest price I have seen in a while, so if you’ve been debating picking one of these up to play with, it might be a good time to buy.

The WL-520gU is the very hackable wireless router I used in my Wifi Radio project.  It’s also the router used in LadyAda’s Tweet-a-Watt and the subject of a talk I gave this year at NOTACON.

It’s interesting to note that Newegg recently added the words “DD-WRT Open Source support” to the product title, so obviously they are aware of how many people buy these routers just to toss the stock firmware and throw on DD-WRT, Tomato, OpenWrt, or the oleg.wl500g.info firmware instead.

ASUS WL-520gU Wireless Router with All-in-One Print Server/ DD-WRT Open Source support

It doesn’t matter if it was inspired by my project or developed independently – I’d love to hear from you!

I’m putting together a talk for NOTACON and I’d like to feature as many projects as I can to spread the word about how powerful, flexible, and affordable these routers are, especially when coupled with a Linux package (DD-WRT, Tomato, OpenWrt, etc.) and USB devices.

If you’d like to have your project included in the talk, leave a comment or contact me directly.

www.flickr.com More in Asus Wireless Router Hacks pool

Flickr: Asus Wireless Router Hacks

Newegg.com has the ASUS WL-520gU Wireless Router on sale again for $19.99 after MIR. This is the cheapest I have seen it this year.  You can do a lot of cool stuff with this device, aside from using it as intended – as a very low cost wireless router + print server, for less than half the cost of the famous Linksys WRT54GL.

Sale ends 12/31.

ASUS WL-520gU Wireless Router at Newegg.com

Hacking the Asus WL-520GU Wireless Router:

In the last part of this series, I selected the Asus WL-520GU wireless router as a suitable embedded platform for my Wifi Radio project.  I have since posted some detailed specs on this impressive low-cost router, revealing it’s powerful Broadcom BCM5354 core, 4MB flash, and 16MB SRAM.  Granted, there are many more powerful routers out there that have USB support, will run Linux in various forms, and have built-in WiFi.  However, the WL-520GU does almost everything we need to build a streaming internet radio and costs under $50 (I have seen them for as little as $26 after rebate), which is very impressive indeed.

To convert this router into a powerful embedded system, we need to make a couple modifications.  First, we need to throw out the stock firmware. It turns out that this router, like many others, runs Linux from the factory.  However, because it was designed to be a wireless router and not much else, the stock firmware doesn’t include a very wide set of features (and certainly was not intended to be accessed by the customer).  Thankfully, there are several open source Linux distributions available that support this router, including my favorite, OpenWrt.  In addition, Asus has made it fairly straightforward replace the stock firmware with our own custom Linux build which can include all the programs, drivers, and utilities we can cram into 4MB of flash.

Warning:

Before we start hacking the router, there are a couple things I should mention:

• From this point onward, your warranty is toast. Don’t even THINK about trying to send a modified router back to Asus for warranty service.  In the end it hurts people like us, because Asus will try to make it harder for people to perform the same modifications in future products.
• You may inadvertently destroy your router. If you are not comfortable with the fact that a misstep during the reflash or a stray solder bridge could ruin your hardware, stop now.  Sorry.  If you really take a wrong turn, you could damage your PC as well, but this is extremely unlikely.  If you do somehow damage your router or PC doing these modifications, I assume no responsibility for any damages!

This tutorial assumes that you have already established the router is basically working by assembling it, plugging it in and checking for it’s wireless signal and internal webserver.  The user manual does a good job of leading you through this process, but don’t use the supplied CD – follow the advanced/manual instructions instead.

Accessing the internal serial port:

The OpenWrt install will be easier if we can find a way to access the internal serial port of the router.  The built-in serial port gives us a way to view Linux boot and status messages and get shell access as well.  The serial port will also come in handy later when we want to add a user interface to the radio.

You will need:

• A desktop or laptop computer with an open USB and Ethernet port.
  
• Your shiny new ASUS WL-520GU wireless router (R1.02)
• A strip of breakaway 0.1″ male header
• A FTDI-232-3V3 USB to serial adapter cable ($20 @ Adafruit) or some other means of connecting a 3.3V level serial port to your PC
• A small scrap of perfboard and a strip of female 0.1″ header (not strictly necessary, see below)

-and-

• A basic electronics workbench with ample light, a temperature controlled soldering iron, a solder sucker, solderbraid, wirecutters, and pliers.  Servo Magazine recently held a contest to see who could build the best electronics workbench for under $100, the results should be helpful for anyone just starting out.  If you’re uncomfortable soldering, find someone else to help you with this part at your local hackerspace.

Step 1 – Open the router

Remove the power cord and antenna (the base unscrews).  Flip the router over and look at the bottom.  You should see something like this:

Note there are four screws that hold the router together, two are hidden underneath the rubber feet.  The feet are stuck on really well, but persistent prying with a fingernail will get them off eventually.  Remove the four screws and set them aside.  The top cover should come off without too much trouble.

Now that the router is open, you should see something like this:

Step 2 – Add a serial port header

Remove the PCB from the plastic enclosure by gently pulling it up and towards you (ethernet ports facing away).

Just to the left of the ASUS logo in the photo below, you will see a 4-pin header that I have installed to access the internal serial port of the router, the router ships without this header.  Instead, you will see four solder filled vias in a row in the same spot.

You will need to use your soldering iron and a solder sucker to remove most of the solder so that the header can be installed.  A higher power soldering iron will help with removing solder from the first via on the left (mine is a 60W Weller WTCPT).  This via connects to a ground plane which sucks heat away from the iron and makes the job more difficult.  Be patient and persistent and you should be able to wick any remaining solder away with some soldering braid if necessary.

Break a 4-pin chunk of male header off the strip.  Pop the header into the board and carefully solder it into place.  If it doesn’t fit, chances are there is still some solder left in the vias.  You should end up with something like this:

The pin functions are, from left to right in the photo:

GND   TX   RX   3.3V

Step 3 – Connect your PC

The FTDI-232-3V3 USB to serial adapter cable provides a handy way to add a 3.3V TTL level serial port to a PC or laptop.  The cable has a flat connector on the serial end that can plug directly onto 0.1″ male headers like the one we are using on the router.  Unfortunately, the pinout of the FTDI cable (given in the datasheet) does not match that of the router.  To resolve this, you have two options:

• Use a tiny screwdriver to pull out the pins from the housing at the cable and rearrange them.  Do not connect anything to the 3.3V pin on the router, and swap the TX/RX so that the TX on the router feeds RX on the cable, and vice-versa.  Don’t forget to connect the grounds!  The downside of this is that now you can’t use the FTDI cable for things like the Boarduino without swapping the pins back.

-or-

• Fabricate an adapter board using a small piece of perfboard and some headers, shown below (click for a larger version):

Here is a schematic of the adapter board:

Shown here are the cable and adapter installed on the router.  Make sure the ground side of the cable is connected to the pin on the header that is opposite from the fat angled trace (the 3.3V line).  Ground is the black wire, on my adapter I marked this with a black dot so I won’t forget and plug it in backwards.

Step 4 – Test the connection

Plug the cable into your PC (you may need some drivers) and open your favorite terminal program.  (I like Zterm for the Mac or Hyperterminal on the PC.)   Using the terminal program, open the serial port corresponding to the FTDI cable (something like usbserial-FTDQ23LB on the Mac or COM3 on the PC, but your setup may be different.)   Set the port options to 115200 baud, 8N1.

Connect the antenna and power supply to the router and plug it in.  You should see something like this appear in your terminal program:

Decompressing..........done

CFE version 1.0.37 for BCM947XX (32bit,SP,LE)

Build Date: Thu Mar  6 10:05:04 CST 2008 (root@localhost.localdomain)

Copyright (C) 2000,2001,2002,2003 Broadcom Corporation.

Initializing Arena

Initializing Devices.

Boot partition size = 131072(0x20000)

et0: Broadcom BCM47xx 10/100 Mbps Ethernet Controller 4.130.31.0

Total memory: 16384 KBytes

CPU type 0x29029: 240MHz
...

If you do, congratulations, your serial port is working!

The lines that scroll by are boot messages from the Linux kernel of the stock firmware on the router.  These messages give you a lot of information about the hardware in addition to information about the operating system and software drivers.  Here is a complete transcript of the boot log from my router.  If you wait a couple minutes for the router to finish booting and hit enter, you should see a command prompt.  From here you can explore and play around with the stock firmware, there is really not much to do here until we reflash the router with OpenWrt.

That’s it for part three.  In part four, I’ll talk about installing OpenWrt and connecting the router to your wireless network.

Update: Part four is now available.

Update 2: There is a new Wifi Radio Discussion Forum, hop over there to ask questions about the project or see what other people are working on!  (4/12/09)

In my previous post about the Wifi Radio project I’m working on, I concluded that the Asus WL-520GU wireless router was the perfect choice for an embedded wireless platform, thanks to its builtin 802.11g WiFi, Linux support, and extremely low cost. (In fact, the price after rebate has dropped since my last post – now would probably be a good time to buy one if you’re thinking about hacking it into something eventually).

Here are the specs on this router, based on an inspection of the hardware and the stock firmware Linux kernel boot log (the complete log is here).

• CPU: Broadcom BCM5354KFBG SoC @ 200MHz (240MHz?)
  • Builtin 802.11g wireless transceiver
  • Builtin 10/100 ethernet switch
  • Core supports 2 serial ports, only 1 is available on the PCB (installed 4 pin header shown in photo above)
• RAM: 16MB Samsung K4S281632I SRAM
• Flash: 4MB MX 29LV320CB
• One USB 1.1 port (USB 2.0 support is broken according to the folks at OpenWRT)
• SiGe Semiconductor 2528L discrete RF Power Amplifier IC
• One external TX/RX whip antenna (RPSMA), internal diversity RX antenna on PCB
• Internal 3.3V DC-DC converter
• PCB Dimensions: 4.0″ x 5.6″
• Supply: 5V @ <2A

Here are some images of the PCB, click for a larger version.

Here’s a closeup of the Broadcom BCM5354 SoC – the brains of the router.  It is surrounded by a 4MB MX flash chip above and a Samsung 4MB SRAM chip on the right.

Overall this is a great little router and an even better platform to build an embedded Linux system, provided you don’t need USB 2.0 support.  If you do, look at the WL-500gP v2 instead, it has two working USB 2.0 ports (in addition to much more flash storage and RAM).