Wednesday, August 7, 2013

SDR Showdown: HackRF vs. bladeRF vs. USRP

This and next year look like the golden age of Software Defined Radio! With three new Software Defined Radios being released by three different companies, there is a lot of choice in terms of hardware. This article compares the HackRF produced by Great Scott Gadgets, the bladeRF produced by nuand, and the USRP produced by Ettus.

Tuesday, April 30, 2013

Using the FPGA of an eeColor Color3

The eeColor Color3 device is designed to enhance the colors in televisions that use HDMI input. The device is supposed to work well in all types of viewing environments, with various lighting situations. But what really got me interested in this device is the chip in the center, which is an Altera Cyclone 4, 30K logic element FPGA (EP4CE30F23C6N). I initially found the device in a post on reddit asking if the header on the board was a JTAG or USB header. The author posted high resolution images and a video of the case being opened. Most of the comments seemed to agree that it was a JTAG header.

The author also noted that these devices were being given out for free (with rebate) by Newegg. So I looked around to see if I could get my hands on one for a reasonable price and found the devices being sold on Amazon (search "eecolor") for about $5 to $15! A development board with one of these FPGAs typically retails for over $100. While 30K logic elements is not huge, it is definitely a good starting place for people want to begin developing on FPGAs.

Sunday, January 6, 2013

Retrieving ST-Link/V2 Firmware from Update Utility


The STM32F3DISCOVERY is a small circuit board with a great microcontroller. The ARM Cortex-M4 chip has 256 KB of flash memory, 48 KB of RAM, USB and more. The board has huge amounts of header pins connected to the microcontroller and has a gyroscope, accelerometer and compass on board. For the 11 USD that this board costs, you definitely get a lot of functionality.

ST-Link/V2 chip is next to Crystal

The board also has 2 USB ports, one which is connected directly to the microcontroller, and the other connected to the smaller microcontroller pictured above (STM32F1) and is used for programming and debugging the device. STMicroelectronics calls the programming solution ST-Link/V2. When used with the proper software, it works quite well. However Linux support was initially lacking, but texane and OpenOCD were able to create working drivers. My goal was to dump the firmware.

Monday, November 12, 2012

Turning Point Clicker Emulation with Arduino and nRF24L01

Turning Point Clicker Emulation with Arduino and nRF24L01

The Turning Point ResponseCard RF, often referred to as a clicker, sends user input to a hub for polling purposes. The user can select a button labeled 1-9 and 0, or A-J and the clicker will send the result to the hub which collects all of the responses. Travis Goodspeed details some of the inter-workings of the Turning Point ResponseCard RF in his blog. He found out that the device always sends it’s answer to the MAC address 0x123456. Then the payload itself is preambled with the clickers MAC address and then the user input, which is ascii 0 through 9 or a question mark. Finally the packet is terminated with a 2-byte CRC.

The heart of the clicker is a Nordic chip, nRF24E1 or nRF24LE1 for later models. This chip includes a nRF24L01 wireless transceiver, which is readily available on ebay for about $2 and can be quickly attached to an Arduino or other microcontroller. This article will discuss how to use an nRF24L01 chip along with an Arduino to emulate and extend the functionality of the Turning Point ResponseCard RF.

Tuesday, March 6, 2012

Dealfun DealWheel - Programming for free stuff

    There was once a website called DealFun. It was a so called "penny auction", It charges customers 60 cents per bid. The item being auctioned starts at zero dollars and every time somebody bids on it, it goes up a penny. Auctions usually had a start time of 24hrs. Within the last few seconds of the auction people really start to bid, every bid placed resets the auction time to 15 seconds. So a $300 item might go for $200, but getting the price up that high requires 20,000, sixty cent bids, or $12000 worth of bids! So there were many people paying for the items, but only one person actually got it.
    In order to incentivise people to use their website, they had various promotions, such as 100 free bids with the purchase of 250 bids. They also implemented something called the Deal Wheel. Which is something like the Wheel of Fortune, so every time the user spun the wheel, they would win a prize. They would win 1-10 free bids or a mystery prize. Spins were limited to once per day. Bids were almost worthless because of the difficulty of actually winning an auction. Mystery prizes were actually physical prizes though. So I decided to write a program that would win a mystery every spin.