I bought this multimeter (Minipa ET-870C) a while ago for $17, great value. I got it because its nice to have around multiple meters for when you wanna measure both input and output voltage/current. I believe it was advertised to have an auto-off feature for 15 mins but it didn’t. This eventually lead to many drained batteries because I often forgot to turn it off after using it. So during a boring weekend when the weather outside was bad I decided to add this nice feature to the meter. I knew it had to be a small circuit to be able to fit inside the multimeter so I picked the tiny25 the smallest micro I had around.
Adding auto turn-off to a cheap multimeter - [Link]
This was actually the first time I ever needed to multiplex analog channels so it was a good opportunity to learn how to use them. My task was to measure the temperature of 32 thermistors (NTC) with a microcontroller and later process that data. Obviously you cant find that much analog input channels on your common microcontroller so you need to multiplex the signals. First I looked for large analog multiplexers with 16 input channels but those are way too expensive. As it turns out its cheaper to use more smaller 8ch multiplexers(example Digikey pricing: 2pcs 16:1 mux from TI is $7.84 while 3pcs of 8:1 mux from TI is $1.53). I was able to get the 74HC4051 at a good price so I started creating the design around it.
74HC4051 Analog Multiplexer - [Link]
320 European cities
The Researchers’ Night is a Europe-wide event bringing together the public at large and researchers once a year on the fourth Friday of September. This year it takes place on 23 September in over 800 venues of 320 European cities in 32 countries.
European Researchers Night 2011 - [Link]
Ever wondered how they test mobile phones for radiation and impact upon the human body? Dave gets a tour of EMC Technologies $1M+ mobile phone (and WiFi) radiation Specific Absorption Rate (SAR) testing facility.
Thanks to Jason Cameron from EMC Tech.
Mobile Cell Phone Radiation SAR Testing - [Link]
Arduino Blog » Blog Archive » Breakfast at Arduino. [via]
For the second year in a row we decided to announce our new products at Maker Faire in NYC.
Tomorrow morning, if you come to the Arduino tent, you will be able to see:
Arduino 1.0, we finally froze the Arduino API, the IDE and the layout of the boards. We’ve made some minor additions to the Arduino connectors to make them more flexible. Tomorrow you will be able to download the release candidate and in 1 month of frantic testing with the community, the platform will be ready and stable.
Arduino Leonardo, a low cost Arduino board with the Atmega32u4. It has the same shape and connectors as the UNO but it has a simpler circuit. On the software side it has a nifty USB driver able to simulate a mouse , a keyboard, a serial port (with more drivers coming later). As usual for Arduino, everything will be released as open source (Core, Bootloader, Hardware).
Arduino Due, a major breakthrough for Arduino because we’re launching an Arduino board with a 32bit Cortex-M3 ARM processor on it. We’re using the SAM3U processor from ATMEL running at 96MHz with 256Kb of Flash, 50Kb of Sram, 5 SPI buses, 2 I2C interfaces, 5 UARTS, 16 Analog Inputs at 12Bit resolution and much more.
Instead of just releasing the finished platform we are opening the process to the community early on. We’re going to be demoing the board and giving away some boards to a selected group of developers who will be invited to shape the platform while it’s been created. After Maker Faire, we will begin selling a small batch of Developer Edition boards on the Arduino store (store.arduino,cc) for members of the community who want to be join the development effort. We plan a final and tested release by the end of 2011
Arduino Wifi Shield. It adds Wi-Fi communication capabilities to any Arduino. Instead of using any of the classic WiFi modules on the market we wanted to have something that will provide the maximum level of hackability to the user. The shield is based on a wifi micro module made by H&D Wireless coupled with a powerful AVR32 processor that carries the full TCP-IP stack leaving room to add your own protocols and customisations. We’ve also worked hard to make sure that you will be able to migrate your code from the Ethernet Shield with minor changes.
We’re also going to show some prototypes of new platforms we’ve been working on: We have robots, new IDEs and more.
It has been a crazy few months and we want to thank ATMEL very much the support that we got on all the new products.
Come over to Maker Faire and have a look for yourself!
Arduino 1.0, Arduino ARM, Arduino Wifi and Arduino Leonardo… – [Link]
Using PWM outputs with an Arduino and a LED @ The Custom Geek. Jeremy writes… [via]
Hi everyone, been a while since my last post, but I have been a busy new daddy. I wanted to demonstrate what PWM output was and how to use it nicely in a sketch. I’m really big on ramping lights on and off (my entire house is set up that way) and would like to share how do accomplish that. I also wanted to use a video to show PWM outputs on a scope to help me explain the process.
Using PWM outputs with an Arduino and a LED - [Link]
The Future of Light Is the LED @ WIRED. – [via]
There’s an excellent reason LEDs have taken on the aura of inevitability: LEDs are semiconductors, and like all solid-state technology, they are getting better and cheaper on a predictable curve. In 1999, a researcher named Roland Haitz, then heading up semiconductor R&D at Hewlett-Packard, coauthored a paper that became the lighting industry’s manifesto. By charting the historical prices of LEDs and projecting forward, Haitz estimated that the amount of light they produced would increase by a factor of 20 per decade, while the cost would correspondingly drop by a factor of 10.
The Future of Light Is the LED - [Link]
Steve has been do some prototyping for his home-built Mac on an Xilinx Spartan 3A FPGA board:
I’ve never been so happy to see a Sad Mac! A boot failure may not seem very exciting, but I’m thrilled that it’s actually doing something recognizably Macintosh-like. That means it’s actually running 68000 code from the Mac ROM, which is drawing stuff to the screen buffer, which is getting read by the video module and displayed to the VGA screen. From here it will be a long, slow road of implementing replacements for the VIA, SCC, IWM, and other components.
It’s trying to play a sound, too, by streaming some data through the sound buffer. With some more work to pull bytes from that buffer at 22 KHz, I could hear the glorious boot beep!
FPGA Mac - [Link]
Nyan Cat – Driving an ‘Adafruit ST7565 Negative LCD Display’ with a Netduino… Fabien writes – [via]
I have been waiting for an excuse to use a Nyan Cat in a blog post and the ‘ST7565 Negative LCD Display’ released by Adafruit being equipped with RGB LED backlights was the perfect occasion. After all, RGB LEDs can create a ‘rainbow’, right? All that’s needed is a cat to go with it and Voila!
Nyan Cat – Driving an ‘Adafruit ST7565 Negative LCD Display’ with a Netduino - [Link]