February 18th, 2010

Mobile 2.4 GHz Spectrum Analyzer

Mobile 2.4 GHz Spectrum AnalyzerMobile 2.4 GHz Spectrum Analyzer

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]

November 17th, 2009

Chumby One released for 99$

Chumby One

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.

November 4th, 2009

DIY iPhone like device

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320240 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]

DSO nano - portable digital oscilloscope

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.

In-Depth FPGA Interfacing of HD44780 Based LCD

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]

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