Arduino GPS

Just to get my hands dirty and wrap it up with the AVR's, I created a GPS data logger - using an Arduino board, GPS receiver chip, 4x20 LCD, and a uALFAT microSD board. A good document on NMEA commands and data formats used by GPS chips is here. Regarding the GPS unit, it was... Continue Reading →


Arduino LCD

My first step, in my foray into embedded systems: interfaced a 4x20 character LCD panel to the Arduino. Details on interfacing any Hitachi HD44780 based LCD panel can be found here. Went for the default parallel LCD's. They're cheap, about $15 for a 20x4 panel on eBay (HD44780). The serial ones cost about 2-3 more.... Continue Reading →

The Arduino

Just got it today :-). The Arduino is a great learning platform for anyone interested in the embedded world. The entire platform is open (hardware schematics, bootloader, lots of examples, etc.). Comes with a programming language that abstracts out lot of the bit-level stuff... but for learning purposes I'd recommend just using straight C -... Continue Reading →


The Atmel ATmega128 AVR is a nice little full featured general purpose 8-bit MCU (i.e. not including MCUs which add on a host of other features like controllers for LCD, USB, Ethernet MAC, DSP, MMU, etc.). For my own quick reference: Feature ATmega128 ATmega168 ATmega8 Flash 128K 16K 8K SRAM 4K 1K 512 EEPROM 4K... Continue Reading →

Which RTOS?

After scouring through a number of MCU's I've decided to go with the Atmel AVR, in particular the ATmega168. But then, my recent adventure into the Slug's hardware, got me thinking ARM. I settled for Atmel's AT91SAM7 series of ARM MCU's. My next thought was how I can run Debian/ARM on it. But unfortunately that... Continue Reading →

Where to get parts ?!

Where do you go for basic electronic parts in the USA!? like discrete components and small chips -- in single quantities, i.e. without having to bulk order them? Back in India (and I think in most South Asian countries) most major cities have streets/bazaars full of electronic component shops (not consumer electronics, but components, semiconductors,...).... Continue Reading →

Choosing a Microcontroller

As I went about choosing what is the good microcontroller to get started on, here's my shortlist: 8/16 bit: Atmel AVR 8-bit RISC Texas Instruments MSP430 16-bit RISC Zilog Z8 Encore! 8-bit RISC Freescale 8-bit Maxim MAXQ Microchip PIC 32-bit: ARM ARM7 series, ARM9 series NXP LPC2000 and LPC3000 series Atmel SAM7 and SAM9 series... Continue Reading →

Slug – Tips

Reducing Memory Given that it has only 32MB of RAM, NSLU2 runs Asterisk as is very well, but if you want to add more daemons you might need to miser down on the memory. Dropbear Dropbear consumes only 2.4MB vs 8.2MB of SSH (who would've ever thought I'd be concerned about savings of 6MB of... Continue Reading →

De-Underclocked Slug

Following the instructions at Overclocking the Slug, I decided to overclock my NSLU2 today, and pulled out my soldering iron. It seems you're not really overclocking it... but restoring it to its normal/full speed of 266MHz. For some reason these units shipped configured to run at 133MHz, done via a pull down resistor (R83) -... Continue Reading →

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