Homemade GPS Receiver Pictured above is the front-end, first mixer and IF amplifier of an experimental GPS receiver. The leftmost SMA is connected to a commercial antenna with integral LNA and SAW filter. A synthesized first local oscillator drives the bottom SMA. Pin headers to the right are power input and IF output. The latter is connected to a Xilinx FPGA which not only performs DSP, but also hosts a fractional-N frequency synthesizer. More on this later. I was motivated to design this receiver after reading the work [1] of Matjaž Vidmar, S53MV, who developed a GPS receiver from scratch, using mainly discrete components, over 20 years ago. All GPS satellites transmit on the same frequency, 1575.42 MHz, using direct sequence spread spectrum (DSSS). GPS relies on the correlation properties of pseudo-random sequences called Gold Codes to separate signals from noise and each other. May 2013 Update Currently, the Pi is running Raspbian Linux. Architecture Front-end Search FFT(y) = CONJUGATE(FFT(s)) * FFT(c)
Dream. Design. Do. » Blog Archive » Reversing an RGB LED remote I have this dream to someday light our basement with RGB LEDs. They often come with remotes and controllers, which are surprisingly inexpensive. The problem with the remotes you get for cheap on ebay is that you *have* to use the remote to change the lights, and that of course limits you to the buttons on the remote. I’d like to make an in-wall dimmer/color changer for LED mood lighting, but with the added feature of being compatible with the existing cheap LED remotes on the market. That means reverse-engineering one. Hardware What’s the first thing I do when I get a new gadget? There’s a 256-Byte two-wire serial EEPROM in the top left, a 5V linear regulator along the lower edge, and an unmarked 16-pin IC that is the main controller. I’m really not sure what the serial EEPROM is there for–perhaps the memory setting I couldn’t get to work? IR Protocol I soldered a couple leads to appropriate points and hooked it up to the oscilloscope to capture the incoming signals. Outputs
SB-Projects: IR Remote Control, NEC Protocol NEC Protocol To my knowledge the protocol I describe here was developed by NEC (Now Renesas). I've seen very similar protocol descriptions on the internet, and there the protocol is called Japanese Format. I do admit that I don't know exactly who developed it. Features 8 bit address and 8 bit command length. Modulation The NEC protocol uses pulse distance encoding of the bits. Protocol The picture above shows a typical pulse train of the NEC protocol. A command is transmitted only once, even when the key on the remote control remains pressed. Extended NEC protocol The NEC protocol is so widely used that soon all possible addresses were used up. The command redundancy is still preserved. Keep in mind that 256 address values of the extended protocol are invalid because they are in fact normal NEC protocol addresses. External Links NEC Electronics, now called Renesas. Navigation How to navigate Sponsors My way of keeping this site alive. You are apparently using an ad‑blocker.
16-Channel 12-bit PWM/Servo Shield - I2C interface ID: 1411 - $17.50 You want to make a cool Arduino robot, maybe a hexapod walker, or maybe just a piece of art with a lot of moving parts. Or maybe you want to drive a lot of LEDs with precise PWM output. Then you realize that the Arduino has only a few PWM outputs, and maybe those outputs are conflicting with another shield! What now? You could give up OR you could just get our handy PWM and Servo driver shield. It's just like our popular PWM/Servo Breakout but now Arduino-ready and works with any Arduino that uses shields: Uno, Leo, Mega, ADK, its all good. When we saw this chip, we quickly realized what an excellent add-on this would be. There's an I2C-controlled PWM driver with a built in clock. Check out our tutorial with Arduino and you can get our documented Arduino library which has both PWM and Servo examples!
Raspberry Pi: 15 Accessories Elevate Pi From Novelty to Workhorse The Pi is indeed moving along at a rapid rate (for the hobyist/Education), as well as interfacing to the Arduino boards, there now exists a small FPGA solution: Bugblat TIF (Tiny FPGA Board) & PIF (FPGA for Raspberry Pi) The TIF is a tiny board (25mm long, 18mm wide). There are two PIF variants available, both of which feature a MachXO2 FPGA. General-purpose microcontrollers such as the one powering the Raspberry Pi are very good at performing a wide variety of tasks. Visit www.bugblat.com/products/pif for more details on the PIF. Visit www.bugblat.com/products/tif for more details on the TIF. Onwards & upwards!!
Mesh Sensors Grove - Moisture Sensor - Wiki This Moisture Sensor can be used to detect the moisture of soil or judge if there is water around the sensor, let the plants in your garden reach out for human help. They can be very easy to use, just insert it into the soil and then read it. With the help of this sensor, it will be realizable to make the plant remind you : hey, i am thirsty now, please give me some water. Note:This sensor isn't hardened against contamination or exposure of the control circuitry to water and may be prone to electrolytic corrosion across the probes, so it is not advisable to be left in place or used outdoors. Features Soil moisture sensor based on soil resistivity measurement Easy to use 2.0cmX6.0cm grove module Specification Specification Platforms Supported Arduino Raspberry Pi TI LaunchPad Application Ideas Botanical gardening Moisture sensoring Getting Started Grove - Help Following documents help in getting the user started with Grove. With Arduino The hardware installation as shown below: With TI LaunchPad
LCD Smartie - A free open-source LCD program! EE Homepage.com Reports: 20080214 Michael Stanley & EE HomePage.comThis report is licensed under a Creative Commons Attribution 3.0 Unported License. Introduction Computer mice are ubiquitous. Figure 1: An LED illuminates the desktop surface, which is imaged by the mouse sensor. Theory In past times, mariners could tell how far they had travelled in a given day by sighting the stars each day, and noting the differences from one sighting to the next. Figure 2: A detail of our example surface.Elaborating on this, Figure 2 shows a hypothetical surface area under the mouse. The mouse sensor is essentially a camera. From these, we can tell that the mouse has traveled a distance equal to -3 "pixels" in the X direction and +2 "pixels" in the Y direction. Figure 3: The world from the mouse's perspective at times A & B. Mouse navigation is by dead reconning. The discussion above covered mouse navigation in two-dimensions. Figure 4: Block diagram of an optical mouse. SW1, SW2 and SW3 The ceramic resonator provides a timebase for IC2.
Inside Tessel, The JavaScript Microcontroller That Is Changing Everything ⚙ Co In early October, startup Technical Machine blew up the crowdfunding scene with its first product: Tessel, an open-source, Arduino-like microcontroller that runs JavaScript on the chip. Finally, web developers could have an easy way to prototype hardware projects. People went crazy for it. Enthusiasm was so high that the campaign met its $50,000 goal in just three hours. (Full disclosure: enthusiastic myself, I was one of the first customers). So why do people care so much about a little microcontroller running a popular web language? Now Technical Machine is shipping its first units to beta users and taking pre-orders for the next round of devices. How did the idea for the Tessel come about? Jon: Last year, we did a senior capstone project at school for Facebook and we were asked to make Internet-connected devices beyond the phone and laptop. What exactly was hard about developing these devices? Jon: Just connecting to Internet was really difficult. The first was a programming language.
Smart contact lenses for health and head-up displays - tech - 10 January 2011 Lenses that monitor eye health are on the way, and in-eye 3D image displays are being developed too – welcome to the world of augmented vision THE next time you gaze deep into someone's eyes, you might be shocked at what you see: tiny circuits ringing their irises, their pupils dancing with pinpricks of light. These smart contact lenses aren't intended to improve vision. Instead, they will monitor blood sugar levels in people with diabetes or look for signs of glaucoma. The lenses could also map images directly onto the field of view, creating head-up displays for the ultimate augmented reality experience, without wearing glasses or a headset. In 2008, as a proof of concept, Babak Parviz at the University of Washington in Seattle created a prototype contact lens containing a single red LED. It works because glucose levels in tear fluid correspond directly to those found in the blood, making continuous measurement possible without the need for thumb pricks, he says. More from the web
Many Signals, One Chip The human ear is a marvel of efficient engineering–using very little energy, it can detect a stunningly broad range of frequencies. Inspired by that prowess, MIT engineers have built a fast, ultrabroadband, low-power radio chip that could be used in wireless devices capable of receiving many different kinds of signals. Rahul Sarpeshkar ‘90, associate professor of electrical engineering and computer science, and his graduate student Soumyajit Mandal, SM ‘04, designed the chip to mimic the inner ear, or cochlea. The chip separates radio signals into their individual frequencies faster than any other human-designed spectrum analyzer and operates at much lower power. Traditional radio chips that could do this would consume too much power to be practical. “The cochlea quickly gets the big picture of what’s going on in the sound spectrum,” says Sarpeshkar.
Skyhook: How It Works > Overview Wi-Fi positioning performs best where GPS is weakest, in urban areas and indoors. Click here for details on Wi-Fi data collection methodology and coverage. GPS provides highly accurate location results in "open sky" environments, like rural areas and on highways. But in urban areas and indoors, tall buildings and ceilings block GPS' view of satellites, resulting in serious performance deficiencies in time to first fix, accuracy and availability. GPS or A-GPS alone cannot provide fast and accurate location results in all environments. Cell tower triangulation provides generalized location results with only 200 - 1000 meter accuracy. Opportunities and Challenges of Connected K-Covered Wireless Sensor Networks ... - Habib M. Ammari Wireless sensor networks have received significant attention because of their important role and many conveniences in our lives. Indeed, the recent and fast advances in inexpensive sensor technology and wireless communications has made the design and development of large-scale wireless sensor networks cost-effective and appealing to a wide range of mission-critical situations, including civilian, natural, industrial, and military applications, such as health and environmental monitoring, seism monitoring, industrial process automation, and battlefields surveillance, respectively. A wireless sensor network consists of a large number of tiny, low-powered devices, called sensors, which are randomly or deterministically deployed in a field of interest while collaborating and coordinating for the successful accomplishment of their mission.