Linduino USB Isolated Arduino Working With DACs and ADCs

Linear Technology products, including ADC & DAC

So a lot of microcontroller (MCU) topics I write about in this blog are mini-research projects for me, because Im new to MCUs and to electronics in general. Through my research I get to learn more about MCUs and how theyre used, and, with a little luck, you get to be informed or amused, or both, by the posts here. But todays topic, Linduino, DACs and ADCs, is even further than normal from my experience and knowledge base, so this post will just give you an overview of the Linduino board from Linear Technology.

"Linduino is a USB-isolated Arduino," an August 11 post on EDN.com, caught my interest because of the *duino name and because the post mentioned applications involving temperature sensors (Humboldt MCU Garden project), audio systems (Humboldt Laser Harp and other music-light instruments) and car systems (Ed Smith is a great resource for vehicle-related MCU projects, possibly something with on-board diagnostics, or OBD). Familiarity with the Linduino board isnt required to do any of the aforementioned Humboldt MCU projects, but at some future point a Linduino could provide major benefits for us. If nothing else, it would be worthwhile to connect with some of the *duino people at Linear Technology, the manufacturer of the Linduino, to expand and strengthen the statewide and worldwide network of the Humboldt MCU community. Plus, their headquarters are in Milpitas, California, so maybe theyll get the urge to drive north behind the redwood curtain and participate in a Humboldt Microcontrollers Group meeting or a Humboldt Makers meeting!

Linduino board

Onward to tech specifics about Linduino. The EDN blog post mentioned above says:

"My pals over at Linear Technology have developed the Linduino board to drive their ADCs (analog to digital converters) and DACs (digital to analog converters) as well as temp sensors and other devices...in addition to the normal shield headers on an Arduino, there is a header that Linear Tech has used for years to drive their demo boards. This computer interface function used to be done with their DC590 interface board. Indeed, the firmware that comes shipped with the Linduino emulates that board, so you can run the original Linear Tech interface program on your PC...The Linduino board will accept all the shield mezzanine boards for Arduino, but has this extra header to control Linear Tech demo boards...Linear Tech also used one of their USB isolators on the Linduino board. This means that the board and what you plug into it are galvanically isolated from the computer you have the USB plugged into. This means you can measure things off a car or an audio system without worrying about ground loops polluting the measurement...Since Linear Tech is also a power supply chip company, they beefed up the power supply on the board, using a switching regulator to replace the linear regulator on the Arduino. This means you can get 750mA out of the power system. Since a USB can’t supply this much power, that means you have to feed the board with an external wall wart. Now you have the power to drive actuators or other heavy loads..."

Were in the early stages of refining the Humboldt Laser Harp, and depending how deep we get into developing the Humboldt family of laser harps and other light-music MCU instruments, there may come a time when well need, or at least want, a board that can be used on "an audio system without worrying about ground loops polluting the measurement." Thats one of the reasons I am interested in the Linduino board.

The main Linduino webpage has lots of info and links about the board, including several internal blog posts and an overview video about Linduino. Since getting two viewpoints about what the board is and does might help you better understand its value, heres the Linear Technology webpage description of what Linduino is:

DC2026A-KIT

"Linduino is Linear Technology’s Arduino compatible system for developing and distributing firmware libraries and example code for Linear Technology’s integrated circuits. The code is designed to be highly portable to other microcontroller platforms, and is written in C using as few processor specific functions as possible. The code libraries can be downloaded by clicking the Downloads tab above and used as-is in your project or individual code snippets may be viewed in the Code section of a supported part. The Linduino One board (Demonstration Circuit DC2026A) allows you to test out the code directly, using the standard demo board for the particular IC. The Linduino One board is compatible with the Arduino Uno, using the Atmel ATMEGA328 processor. This board features a 14-pin “QuikEval” connector that can be plugged into nearly 100 daughter boards for various Linear Technology parts, including Analog to Digital converters, Digital to Analog Converters, high-voltage power monitors, temperature measurement devices, RF synthesizers, battery stack monitors, and more."

Humboldt Laser Harp and Ed Smith

Linduino is not inexpensive, so participants of the Humboldt Microcontrollers Group wont be buying them on a whim like a $3 Arduino Micro clone from China. But if someone has a genuine need for the board, especially a business-related, revenue-generating need, it would be good to know its available. You can order the board from this Linear Technology page, and there are two options. One option is the DC2026A-KIT for $125, and the other is just the DC2026A board for $75. Digi-Key, Newark and Arrow are also distributors for Linear Technology.

So now you have a general idea of what the Linduino board is and can do, and youve got links above that lead to more info about this member of the continually-expanding *duino family. Ill have to check in with Ed Smith to find out exactly what value this tool might have for us while working on the Humboldt Laser Harp, the Humboldt MCU Garden or any other MCU projects our MCU group or maker group gets involved with.

**********

Read More..

Solar Energy And Arduino Solar Charge Controller

Theres an intriguing microcontroller (MCU) project in an August 8 article on Design News titled "Gadget Freak Case #260: Arduino Solar Charge Controller." I havet read a lot about solar energy and Arduinos, or any other MCUs, so I took a closer look at the article.

Residential active solar energy system (from Wikipedia CC)

Many Humboldt County people seem interested in solar energy, although the often-foggy or cloudy climate of Arcata, Eureka, and other coastal communities isnt as well suited to solar energy collection as the climate of New Mexico or Arizona cities. However, it is still good to be experienced with technologies used outside the North Coast, and there are plenty parts of Humboldt County not immersed in marine fog banks or redwood forest mists. For this reason it would be useful for participants in the Humboldt Microcontrollers Group to know the basics of active solar energy systems and to have experience with the electronic components and operation of those systems. The topic of the Design News article above isnt an inexpensive basic active solar energy system, but I think Ill do some research regarding different types of inexpensive systems for a future group project.

Solar charge controller schematic from CirKit.com

The solar charge controller that is the topic of this post is located between the solar energy collection device and the energy storage system, usually a battery. The controller regulates both the voltage and the current going to the energy storage system from the energy collection device. The schematic at the right from CirKit.com shows the general concept (although that schematic is not from Gadget Freak project). The Design News article describes the function of the Arduino this way:

"This gadget uses Arduino to control the whole process and takes a voltage reading from the solar panel and the battery to be charged. Then, according to voltage levels on either side, it charges the battery using PWM control signal. Energy flow is driven with MOSFET transistors that ensure low energy loss. The charging controller is equipped with basic filters on both the battery side and the solar panel side. It is also equipped with things like overcurrent, overvoltage, PV panel reverse current, auto load disconnection, and overcharge protection."

Gadget Freak #260: solar charge controller (Design News PDF)

The solar charge controller build instruction PDF is linked to in the article, and seems like a good quality document. It has pictures, circuit drawings, Arduino code, and the type of helpful tips that many project documents do not include. An example of the helpful tips is where the project creator describes how to choose MOSFETs. For people who arent already familiar with MOSFET properties and how theyre used, he says this about drain source voltages for MOSFETs:

"When the MOSFET is turned off, the whole supply voltage will be measurable across it, so this rating should be larger than your supply voltage to provide sufficient protection so that the MOSFET does not fail. The maximum voltage a MOSFET can handle varies with temperature."

He also talks about whether to use an n or p channel MOSFET, continuous drain currents, thermal loss, gate threshold voltage and more. Tips like this are especially useful to people like me who are new to microcontrollers.

In months and years to come, it is my hope that the Humboldt Microcontrollers Group will build many MCU devices and systems. Nicks automated chicken coop door is the first one, as far as I know, and the Humboldt Laser Harp is the second, I think. It would be great if we can develop and put online as much information as possible about these MCU projects, assuming theyre not going to be commercialized so they can earn us millions. Or even thousands. Anyway, part of gathering, organizing and publishing this MCU project information should be a good documentation format. There are many possible formats, but the Gadget Freak build instruction PDF used in the solar charge controller project seems like a good place to start if someone in the MCU group doesnt have a different project information format they prefer.

Gadget Freak (from Design News and Allied Electronics)

This Gadget Freak topic appears to be a regular feature of the Design News website. This solar charge controller is labelled #260. I dont know if that means there are 259 previous Gadget Freaks, but here are links to The Best of Gadget Freak Volume 1 and The Best of Gadget Freak Volume 2. Design News collaborates with Allied Electric, and they invite you to submit your electronics projects for publication. This is just one more way that people in the Humboldt MCU community can participate in the expanding world of microcontrollers and possible earn a few bucks. The Gadget Freak page on Allied Electrics site says:

"Are you a Gadget Freak? Allied Electronics and Design News would like to send you a check for $500 to spend at alliedelec.com or anywhere you please! Submit your design for a gizmo or gadget that any Gadget Freak would appreciate, and you just might win! If your project is selected, you’ll receive a $500 check from Design News and will be featured in an upcoming issue of the magazine with your invention. In addition to the $500 awarded for being selected as a Gadget Freak, all selected gadgets...will be included in the Gadget Freak of the Year contest. Starting in November, the readers of Design News will then vote on the best gadget...The winning gadget will receive an additional $6,000 with two runners-up who will receive $2,000 each."

If youve built solar energy devices or systems with MCUs, it would be great if you came to one of the every other Thursday meetings the MCU group has. The next meeting will be on Thursday, August 24. If you cant make it to the meeting but would be interested in discussing your solar energy device or system, please email me at arcatabob (at) gmail {dott} com

. It would be great to meet you for coffee and a tech discussion, or possibly youd be willing to show the MCU group your MCU in operation!

**********

Read More..