Mesh Sensors Micron Technology 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.
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.
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
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. 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  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)