Arduino DS1621 Based Temperature Monitor

I just got some DS1621 I2C 5V PDIP-8 Temperature Sensors and with a quick google search I found some code from Jon McPhalen.

 http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1198065647

I added my LCD screen code and a Celsius to Fahrenheit float conversion and I had an easy Temperature Monitor built up in less than a 30mins. Fun lunch hour project! .... Now back to work :P

Click the link below to get to my modified code:
http://www.divshare.com/download/15351662-27b

Now I have to clean up the code and combine the Real-Time-Clock and Temp Sensor into one build... but that is for another lunch hour;P

DesignSpark PCB for Touchstone Contest

Well I finally finished up my PCB for my entry in the Touchstone Semiconductor TS1001 Design Contest... and not a moment too soon (the deadline is July 29th). I ordered a 5 day turn on the PCB and next day shipping from PCBnet.com and should have just a couple days to build it up, test it, and get my video done for the contest.... always cutting it close.

This was my first PCB done with DesignSpark and I have to say I am pretty impressed. I easily created new library's for my custom components, edited the DRC rules, and kicked out some Gerber and drill files. I don't think DesignSpark has the full capabilities of EagleCad, but for just kicking out protoboards I am happy with DesignSpark.

Work Hard.... Play Hard

Well I believe I have officially solved a doosy of an electronics problem, which now seems pretty obvious (Isn't that always the case).

I have been banging my head against the wall for weeks trying to understand why a bit of RF noise in the 100MHz range would cause a product I was working on to lock up? Also once I fixed that issue, why one type of display would work and the other would break?

It all boils down to the two displays even though schematically the same used different amounts of ITO to connect the SDA line and GND line of the Chip-On-Glass LCD controller to the metal flex cable. That increased resistance on the SDA & GND line (~400 Ohms on one display and ~200 Ohms on the other) casue the Ack I2C signal coming back from the LCD controller to read as a logic "1" instead of the proper "0". By changing the SDA & SCL to higher value pullups on the display the ITO resistance effect is less noticable. Obvious now right :p

Well I am going to celebrate with one of my favorite beers (Crow Peak Porter brewed in Spearfish, South Dakota, USA) and sulk a bit because I now have a lot of work ahead of me documenting this issue and updating the three pieces of my design that now need correcting.

Free Beer Tomorrow.... The Sequel

Back in Sept 2010 I blogged about some of my favorite "Free" software tools and over the years I have just found a ton of neat tools that people have freely distributed, so here are some more!

I am defiantly a Texas Instruments Graphic Calculator lover. Even though I do have several Slide Rules... and know how to use them; I pick up and use my TI-89 daily.

I found this Virtual TI Calculator Emulator written by Rusty Wagner. This program uses a ROM image from the actual TI calculator and emulates it on a PC. He has also provided some picture "skins" to match the actual calculator.  This program comes in real handy when I'm in the lab or out of the office without my calc and need to crunch some numbers.

http://www.ticalc.org/archives/files/fileinfo/84/8442.html

I've never been much for RPN calculators, but I do love the HP calcs easy Unit conversion function. This was one of the huge disappointments with the TI-89; you have to actually go into menus to assign units to be able to convert them; the HP calc does it with a couple quick button presses.  Below is a screen shot from the EMu48 HP Calc Emulator by Christoph Giesselink.
http://hp.giesselink.com/emu48.htm

It has been a couple years since I've spun a set of PCB Gerbers for a home project; I've been busy trying to save the USA's Social Security program by having a few kids!

I was pretty familiar with Cadsoft's Eagle CAD but I figured if I am going to switch tools I might as well do it now while I am rusty. I downloaded and have started making a board with RS Components DesignSpark PCB. and I have to say for a Schematic/PCB tool that has no limitations on PCB size and is free.... I am impressed.

DesignSpark's Library and tool wizard is really intuitive and the pdf tutorials that come with the software are great. I would highly recommend checking out DesignSpark for an entry level SCH/PCB tool.
http://www.designspark.com/pcb

Ridiculously Simple Arduino LCD Clock

Well I got my Arduino Uno board a month or so ago and I've been dying to build up a quick project. I already got my Parallax Serial 16x2 Character LCD up and running, so I thought a simple add-on would be a basic Real-Time-Clock. The Dallas/Maxim DS1307 is a 5V I2C based RTC that looked pretty popular.

I soldered up the DS1307 to an Ardunio proto board and placed a CR2032 Coincell holder on the bottom. It fits nicely in between the boards when they are stacked.

(Schematic from http://www.ladyada.net/learn/breakoutplus/ds1307rtc.html)


A quick search on Google brought me to Maurice's software and a cut and paste later with a few LCD tweaks I had a working Arduino LCD Clock. Too simple; this literally took me less than 30mins to throw together.... I did this over a lunch hour and still had plenty of time to finish my sandwich :-)

I2C Rant

Just wondering why the I2C Users Manual/Spec doesn't have this picture in it. This is exactly what I was looking for to determine how much rise time my I2C signals can tolerate. Section 6.2 does cover this a bit, but I like pretty plots.

The passing of two Greats!

Two great role models of mine have passed. I have enjoyed reading their articles and getting the opportunity to sit in on one of Bob's "Analog Power Point" presentations at Arrowfest a few years ago.

Bob Pease


Jim Williams

It will be interesting to see who will fill these shoes at Electronic Design and EDN; there are no shortage of talented Application Engineers, but I wonder if ..... In today's fast paced do more with less engineering depts; can someone obtain the "depth" of knowledge to replace Bob & Jim in a world that requires so much "breath" of knowledge to be successful.

I like Chris's spin on this topic.

P.S my favorite Programming Language is solder as well :)

It's ALIVE!!!!

My hacked up circuit for the Touchstone Semiconductor TS1001 Opamp Design Contest works!!!! I wasn't too worried about it working, but I wasn't sure if I could squeak under the 1V @ 5uA power consumption requirement the design contest entries must meet.... I've got 0.5uA to spare. Like Dave Jones says "I could fly half way to the moon on 0.5uA"

More details to come, but I have a board to layout, video to shoot, and documentation to pull together before I can divulge all the details.

If you haven't signed up for the design contest; sign up deadline is the end of June and entries must be in by July 29th.

Extra Large Seven-Segments

I was digging through my closet of goodies the other day and found several extra large seven segment displays. I glued them together and wired them up to make a nice new sign for my office.

 I used some 100 Ohm DIP resistor networks for series current limiters and hot glued them to the back of the displays. Not super high techy since I hardwired the "Eric", but I figure I could easily wire up the rest of the segments and drive them via my new Arduino.... maybe a project for a rainy day.

Arduino, Open Source Sexyness!

I just got my Arduino Uno board in the mail this week and I am pumped. Why would a guy whose designed embedded platforms around a dozen or so different micros be interested in a "Beginner" Atmel AVR platform. Other than it's cool.... I've been looking for a new embedded platform for my home/hobby projects. 

Back 8 years ago or so I fell in love with the Zilog Z8 microcontroller it had a ton of application notes and software code samples which made hobby projects a ton easier to implement. I have always considered myself a Hardware guy, but I can blink LEDs, light up Character Displays, and talk to SPI and I2C peripherals without too much trouble. But I always love it when I have a really well written software oriented app note to help me along. I started to steer away from Zilog, because even though they were great for my "hobby" projects I didn't see myself using these parts in a commercial product, for my day job.

Then back in 2006 or so I managed to get my hands on one of these cute dev kits, Silicon Labs C8051F300 Toolstick.

This was one of the first USB based Devkits that I noticed on the market, I am pretty sure it even came out before the TI MSP430 one. I loved the concept of an extremely low cost dev kit to get me started. Silicon Labs has a reasonably good IDE and a Keil 4KB code limited version of the 8051 compiler to get you started. The 4KB limit bugged me because I had 8KB of Flash to use up, so I quickly switched over to the open source SDCC 8051 compiler and even though the code wasn't compiling near as tight I was happy. But then Silicon labs forgot about the hobbyists and discontinued the PDIP package version of the parts and left me with the QFN/"Belly" pad commercial parts.... this sucked! I have relatively good soldering skills and even though I have successfully soldered these types of parts on boards hundreds of times.... I just didn't want to screw around with that anymore.

I came late to the Cypress PSoC party; these parts were already being used in a ton of commercial products and almost every other Circuit Cellar article used a PSoC as well. The IDE was free, the Imagecraft M8C compiler was essentially free, and best of all they still offered the parts in PDIP and non-belly pad SMT versions.... thank you Cypress!!!! I have used PSoC's in a half a dozen or so commercial products and just as many small hobby projects. There is a bit of a front-end loaded learning curve with the PSoC, but that is compensated by the huge app note offering and public support in the forums. The thing I love about PsoC is how configurable it is, the thing I hate about PSoC is how configurable it is.... most times I don't need 12 configurable analog blocks and a butt load of digital blocks, I need a simple 8-bit micro to bang out commands out of a serial port or toggle a few GPIOs.... so the PSoC is a bit of over kill for most of my hobby projects.

The Arduino is an open source hardware platform based off the Atmel 8-bit AVR Microcontroller. The micro has a Serial (USB Device) based boot-loader pre-installed in the AVR, so no external programmer/debugger is needed to program the device. The Arduino team (a handful of Italian dudes) also created an open source IDE that makes use of the GCC AVR compiler. The cool thing is this IDE & Compiler runs perfectly on Windows or Linux...... So I am programing an open source hardware platform, using an open source IDE & compiler, that is running on my open source Ubuntu Linux distribution; now that is sexy!!!!

Now open source is cool, but how well does it work? All I can say is within 5 mins of pulling my Arduino Uno out of the package I downloaded one of the example "Blinky" light projects (Sketch) and had a blinky LED going. Within 15mins I had a Parallax Serial 16x2 LCD up and going.... I remember spending most of my Christmas vacation getting a character LCD lite up on an MC68HC11 eval board in college. To be honest it took me longer to find the Parallax Serial LCD command to turn off the blinking cursor than it did for me to get the Arduino running. The IDE is very intuitive and there are a ton of forums and resources for this platform.

I think I've been converted and the Arduino will be my hardware platform of choice for fun side projects.


Some great Arduino resources are listed below:
http://www.arduino.cc/
http://jeremyblum.com/category/arduino-tutorials/ 
http://www.adafruit.com/ 
http://www.sparkfun.com/