Open Source Software is Amazing! Our First Data Logging Software:

We just uploaded to our website our earliest attempts at creating an open source version of our full featured SiGZiG software that is used to interact with and collect data from our data loggers. This version will be limited to The Zig-4 hardware for now but may be adapted for more hardware in the future.

We decided to take advantage of the Processing IDE and libraries to make this simple program and want to give a big thank you to all the hard work that is being done at processing.org. It is only because of the ease of use of processing that a simple program written by our engineer for logging during testing could come to rival our closed source (and expensive to make) version.

It is not without bugs and glitches right now but we will be updating it frequently and will do some major fixes when our programmer gets back from vacation.

We are also still working on some visual tweaks but it is coming along as you can see below:

Using Input Impedance to Measure Current

Input impedance on measurement equipment is usually kept as high as it can in an effort to prevent loading down the signals the equipment is measuring. For example most general purpose digital multimeters aim for an input impedance of at least 1M ohm. The Zig-4 has a lower input impedance of 330k ohms but this is still high enough for many/most situations. That being said it is still important to understand input impedance and its affect on your measurements.

In this post I thought it would be fun to actually take advantage of the 330k input impedance of the Zig-4 as a sort of low current sensing.

The goal: To see if we can use the Zig-4 to detect a change in current in the very low nA range.

Even though most everything can be calculated, I thought it would also be nice to back up some of the calculations using actual measurements. I wanted to use a recently acquired Keithley 480 Picoammeter and on the lowest setting so the first order of business was generating a really small known current.

Using a 1G ohm resistor and a 1.25V voltage reference we can generate a current of 1.25nA.

The resistor is 1% and the voltage reference is not exactly 1.25V plus the meter could be off a bit... but overall that's close enough.

I then added a 100M ohm resistor in series with the 1G ohm resistor effectively lowering the current to a calculated 1.136nA

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Again, close enough.

Now lets swap out the Keithley 480 picoammeter with the Zig-4 and do the same change in current to see what kind of signal we get. The current in both cases will be a little lower because now there is the additional 330k of the SiGZiG.

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Above is the setup except I switched back and forth between the 1G and the 1G+100M ohm resistor. Below you can see the signal I was able to get. The Zig-4 does have a small amount of programmable gain, so in all fairness the below plot is with it set to a maximum gain of 8 giving it more bits for the range it was measuring.

So by using the input impedance of the Zig-4 to our advantage we can actually use it to monitor small changes in current down to the sub nA range. In the case above we were able to clearly pickup a change in current of only 115pA (113.5pA to be exact).

Cases are close. Software is sleeker (well, getting there).

Almost finalized our case design before the kickstarter launch.  Small changes, but we are detail freaks over here.  The case on the left is our latest version.  Slightly deeper black, bevel around the logo, and took care of some screw thread issues. 

Data logger cases keep coming

Software is moving along - getting sleeker and smoother but still has a ways to go.  The end result will look very similar to this.  By our next post, we hope to have some video to share with everyone of the Sigzig working full-time with our beta software..

Data Logger Beta Software

As develop cases, software, and high performing analog electronics we are always looking for good resources.  One of these is www.eeweb.com. They recently listed SiGZiG on their website as a "site-of-the-day".  Check out the forum and site!

Using @99designs to make our data logging software look nice and fancy.

Our original software was built specifically to test and evaluate advanced chemical sensors.  It works great for our R&D but is limited to Windows, has a slow refresh rate, and is best for internal use. 

With the development of the SiGZiG, our modern usb data logger, it became apparent that we must create a software package that is silky smooth and works across all desktop operating systems.

For the past 3 months, software has been built up with a focus on functionality.  Here is the prototype:

Data logger dev software

This obviously isn't pretty...so we used @99designs and received multiple design ideas for the user interface.  Here is the concept that we liked and we are heading in this direction:

USB Data Logger Software Concept Sigzig

Additional changes have been made since this concept.  We are currently on version 0.8 of our software and are looking to have version 1.0 by the end of April working full speed on our SiGZiG prototypes.  When we launch our crowd sourcing campaign you'll be able to see all the action.

Why are there Data Logger Cases Everywhere?

When designing the SiGZiG usb logger, we deemed the quality of the case as highly important to help with noise reduction, durability, coolness factor, and to reflect the internal build quality.  Some told us that we should go the plastic route, but that has already been done for decades by the current manufacturers.

While our first prototype cases came from Protolabs (great for quick-turn prototyping), we had to search for a more cost-effective solution for mass production.  Working with different manufacturers on case materials, coatings, sandblasting, metal injection molding, machining, and anything else they/we could think of, we are getting some pretty great results.

Here is the latest batch of test cases.  Enjoy!

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Good Question! Data Logging Outputs, Inputs, and Open Source

Hello World.  We are just getting going here and are already receiving good questions.  We will periodically post some of your questions here.

Very interesting product you have here. I'm interested in the open nature of the hardware and wonder if there is an SDK or API available to perhaps run the device without USB or perhaps an alternate serial UART.

Any info on the pinouts of the device(s)?
Any outputs available on the device?
Can the inputs be configured for discrete digital inputs?
Any other power input options besides the USB connector?
Is the device running firmware which may be modified or updated?

Again, lots of questions might just have to wait for the official release! Thanks

The data logger hardware is not open but we will have open hardware add-on boards and we are going to have open source examples of computer software to interface with the device. That way people can make their own GUI or format the data into a more usable format (i.e. if you are measuring color, it shows the color not just 3 plots for RGB, things like that).  

As far as pin out, there are no digital inputs or outputs on these first two versions but later models will include digital communication to sensors or options to toggle a digital pin based on an event in the analog data.  As far as power, again, only USB for these versions but later versions will include battery power and wireless communication.  The firmware is not user modifiable.  

No problem with asking questions.  Thank you for your interest.