Miguel writes :

The analyzer has become my best travel companion. It’s very discrete: everyone think you are playing with a mobile phone!. You can see in a moment what are the used frecuencies / channels at your location. One of the most interesting things if to carry it in the pocket in exposure mode and walk sometime in your neighborhood. In this way you can find easily what are the free frecuencies or channels. With the time, I learned how to distinguish between different device

Mobile 2.4 GHz Spectrum Analyzer: [via HackADay]

Chumby One was just announced on bunnie’s blog. You can get it now for 99$ pre-order price but once they start shipping the price will go up to 119$. You can read here about the story behing Chumby One and how bunnie tried to keep the price low by using every feature of this new processor from Freescale the i.MX233.  It turns out the i.MX233 has 3 internal switching regulators and it uses only one inductor to do the job. Next to the switching regulators the i.MX233 has even more analog features integrated like : audio codec,  speaker amplifier, USB PHY, video DAC, battery charger and more. This played out an important role in the final price of the Chumby One. You can read more about it on bunnie’s blog.

320×240 LCD with resistive touch screen, USB, SD card, 3d engine, USB, movie playback, UI interface, sprite engine , would you believe all of this is handled by an AVR 8 bit device with 4K RAM running at just 12 MHz ? You’d better believe it because it’s real. Well the ATmega644 runs at only 12 MHz because it’s powered at 3.3 V so as you can imagine it’s stretched to it’s limit. The LCD with the integrated controller helps allot taking the job from the microcontroller.

The Pacman demo just fits in 8K flash and 512 bytes of RAM. It uses the sprite engine and runs at > 60fps. The images and animations don’t even touch the RAM they go straight from the SD card to the display. It turns out reading a 512 byte block from the SD takes ~1ms.

Source code, demo files, Eagle PCB and schematics are provided at the projects SF page.

DIY iPhone like device: [via Hackaday] – [Link]

I was really interested about it when Seeed Studio first announced the DSO nano on their blog, unfortunately I was not able to get one of the beta’s which they offered in a limited number at a lower price. The specs they released don’t advertise for too much power from this portable but it’s style and the fact that is portable together with the low price tag should compensate for the lack of power. And don’t get me wrong on the power issue, the 1 MHz bandwidth is still enough to cover your hobby needs. For me the only big disadvantage is the fact that it has only one channel, but it compensates with the ability of recording readings that you can later compare with the actual reading.

I would love to give you more details about this portable oscilloscope, but I have to wait until I can get my hands on the DSO nano. I’m currently waiting for Seeed to list it on their product page so i can place an order.

This project illustrates the interfacing of a HD44780 based LCD to the Xilinx Spartan-2 XCS200 FPGA using delayed Finite State Machine (FSM). While using a microcontroller to display text on the LCD is a fairly simple task, interfacing the LCD with a programmable logic device is a different story. The FSM controls the timing and generation of the signals required for data communication, making the process a lot easier.

The HD44780 LCD uses minimum 2.2V voltage for logic ’1′ and maximum 0.6V voltage for logic ’0′ for a given Vcc of 4.5 to 5.5V. These voltages are easily managed by the FPGA, using LVTTL mode. The project makes use of the write operation only in communicating with the LCD, so the RW pin is not used. The execution time delay, used to determine that the current write operation is completed, is 40ns. A 4-bit counter is used to control the instructions (the counter is controlled with the CE signal).

When electrical power is applied to the circuit the FSM enters its first state, the Pwr_Up state (check the diagram). The next state is the Pwr_Up_Delay state which lasts 45ms. The device has a multiplexer that puts the CE signal of the counter on high during these two first states. The next state is the Off_Pwr_Up_Delay, after which the FSM enters the Write_Data state (Enable pulse generation state machine). Next is the Data_Setup_Delay state, in which a delay is generated to make sure the setup time before the rising edge of the Enable pulse is adequate.

The Enable must has to be at least 240ns to be valid, and this is handled in the E_Pulse_Hi, E_Hi_Time and E_Pulse_Lo states. The E pin of the LCD is set on high during E_Pulse_Hi and E_Hi_Time states, and low on E_Pulse_Lo state. The next state is the Proc_Comp_Delay state, in which the delay for the current instruction is activated. The next state is Load_Next_Data and the FSM can either move back to Write_Data state and continue to send instructions to the LCD or go to the End_State.

The FSM and hardware layout is using the Xilinx ISE 8.1i VHDL Compiler. Check the article for a pdf file with additional instructions, diagrams and schematics and look into the datasheet of the HD44780 Based LCD for detailed specifications.

In-Depth FPGA Interfacing of HD44780 Based LCD: [Link] – [Link2]

For all tweeter users that possess some hardware hacking skills, this is the Tweeter Wireless Display. It is basically a modified wireless router, stripped of its original case and mounted on a custom made wooden chassis. The text is displayed on a small screen which is mounted on the top side of the chassis.

The router used in this project is the WL-520-GU from Asus, which features a 4-port switch and supports both IEEE 802.11b and IEEE 802.11g. The device uses OpenWRT to run a Python script that fetches the 20 most recent tweets. The script is taken from a USB flash memory and the information is displayed on a serial alphanumeric LCD from Sparkfun.

The project is entitled Tweetser, a combination from ‘tweet’ and ‘serial’ and is surely an appealing piece of equipment for any tweeter lover out there, especially for the ones that are also hardware enthusiasts. I personally still think that a PC would be more suitable for this kind of things as it also features… you know, a keyboard and a slightly bigger screen. Nevertheless, it’s still a nifty little project that can be useful if you’re a tweeter maniac.

Tweeter Wireless Display: [Link] – [via]

Also entitled Arduino LCD Backpack ‘Sandwich’ by its illustrious creator, this is a simple do-it-yourself project using an Arduino microcontroller and a small LCD display. The MCU runs at 16Mhz thanks to the ceramic resonator (the light-brown one, located near the microcontroller). The LCD is an alphanumeric one with two lines of 16 characters (the color used is amber/orange, which gives it a nice, old-school feeling). The contrast of the LCD can be adjusted using a potentiometer.

The Backpack has an IR input receiver module connected (the small silver box on the left side) and a 6 pin FTDI style serial header soldered directly to the wires, which is used for software download and also for the 5V DC power supply. The project is free, for non-commercial use only. More details, pictures and source code available in the link below.

Arduino LCD Backpack: [Link] – [via]

An older project (but quite interesting nevertheless), this is an RDS decoder that is able to display various information on a 2 lines with 16 characters alphanumeric LCD. The decoder is connected to an old radio receiver and was originally designed to use the Atmel AT90S2313 as its brain, coupled with TDA7330B RDS demodulator as the decoding-chip. The newer version had the AT90S2313 replaced with the ATtiny2313 microcontroller.

The device can display service name, RDS clock, TA (Traffic Announcement) flag status and scrolling 64 characters long radio text. The decoder requires a Stereo multiplex signal as input, which can be found at the input pin of a Stereo decoder integrated circuit in most radio receivers. The code is written in assembler, which provides for the fastest implementation. There is also a C version of the code, but apparently it’s too big for the 2KB flash memory of the ATtiny2313. However, an improved, smaller C version might be available sometime in the future.

Check links for .zip with PCB layout, schematics and source code (for both the ATtiny and the AT90).

RDS Decoder using Atmel Microcontroller: [Link] – [via]

Central heating systems has been a good solution for many homes and even offices for quite some time now. If you own such a system I’m sure you would like to be able to control it remotely from your bed or even from a computer. This project presents such a controller. It has a 5/2 days programmer, that is 5 week days, 2 weekend days or for entire week.

The control panel allows you to turn on and off heat and hot water independently. It has 10 program entries that you can save and you have the possibility to manually override the program. Basically it is composed of two modules: the relay module that is placed at the boiler, which also has the 9 pin D connector for serial connection and the programmer panel which is connected to the relay module by a UTP cable.

The programmer panel has a 2×16 LCD display and five switches to select the desired program or manually control the central heating. PIC16F628A microcontroller was used in this project as the system’s brain. Dallas DS1307 was used for time management and for saving time settings in its memory. It is powered by a backup battery so it will not lose the memory data when mains power is taken. Max202 IC takes care of the serial communication.

Because of the UTP wire lenght the rellay output of the PIC can not drive the rellays directly, so a driver is used from Quasar Electronics. It is also a good idea to use protection diodes on those outputs to take care of spikes.

LCD will show the current operation mode for central heating and hot water, the on/ off state and the time. Switch 1 and 2 turns the system on/off , switches 3 and 4 are used for manual control and switch 5 is used for programmer setup. A detailed explanation of the programmer’s operation is presented in the link with all schematics and construction procedures as well as the software for the microcontroller.

PIC-based Central Heating Controller: [Link]

When using different types of batteries it can be quite a pain in the neck to be able to find a single tool to recharge them all with, because most chargers only work with one or a few types of batteries. But here is a charger that can do it all, from sealed lead acid batteries to Lithium Ion and Lithium Polymer – the multi-chemistry battery charger.

The device has two channels and can charge two different types of batteries simultaneously up to 2 amps each. One of the channels can also be used as a discharger. The types currently supported are Nicad, NiMH, LiIon (or LiPoly), sealed lead acid and rechargeable alkaline batteries. The charger uses an ATMega32 microcontroller and a 2 x16 LCD display with a 5 key keypad that enables the user to set and view all necessary parameters, which are saved in an EEPROM and charging and discharging values. A fixed voltage, current limited output, a fixed current, voltage limited output and a variable PWM output are also provided as a bonus.

Two separate circuits are used for charging and discharging, respectively. The brain of the charger is the microcontroller working on 16MHz that generates two 10 bit 16 kHz PWM signals. It also manages the LCD and the keypad and executes the algorithms needed. Powering the microcontroller section is done using a 0.5A 5V regulator. The charger automatically detects if a battery is connected and starts charging/discharging according to the parameters entered by the user.

This project is developed as a commercial product, so no code is released by the designer. Still, he is willing to give additional information about charger design and share some of his experiences with various battery types. Also, the charger, discharger and microcontroller schematics are available in the link below.

Universal Battery Charger: [Link]