Towards the end of 2011, I have been moving several websites to a new hosting provider. All have been moved, except this one. The details are technical, but that is the main reason I did not update anything here, as I was preparing the move. As it turned out moving everything to a new host, and keeping everything together was not as easy as expected. To be continued this year.

Then, on the greenhouse project: weather has been lousy for growing anything since july. Low temperatures, *lots* of rain. Winter has not given any frost, which is what the ground and some plants need in order to provide good fruits next summer (such as strawberries). This was all monitored by the greenhouse project until it stopped working. Turned out that the waterproof housing for the battery was not so water proof Electronics are largely ruined so I am in the process of rebuilding that. I want to replace the Xbee’s with WiFi connections though as I have a wifi network already up and running, plus it would eliminate the need for a Xbee/Internet gateway. Additionally, it frees up the internet gateway Arduino for another sensor node. I am thinking about turning it into a weather station…

Finally, I have spend quite some time on building my own arcade cabinet! I wanted to relive those games from my youth (donkey kong, zaxxon, defender, 1943, and later Mortal Kombat, Street Fighter, etc). I wanted to develop my woodworking skills as I had never worked with a large saw-table or router. So, I figured this would be a great project. I have made *many many* pictures and am in the process of doing a writeup. I will share as much as I can so you can build your own machine if you want to. But, there is a lot to write, and the cabinet itself is not yet fully finished, so the writeup may take a bit before its here, but its coming!

This is what the thing looks like at this point:

Finally, the LED matrix word-clock is still in development. I have ordered a second batch of PCB’s with some slight improvements (though it did not come out perfect yet, lots to learn). I want to share all that stuff, designs, schema’s, etc as well, but I am still looking for a way to do so. Maybe put it into a sourceforge or google code account so I can keep track of versions. Please keep in mind that all this stuff (PCB design, electronics, woodworking and all) is all new stuff for me, so I am learning as I go. If you have any tips and tricks to share, please do so!

The greenhouse sensor though is now completely off-grid: A 11W solar panel is connected to a solar charge controller which charges a 12V-2Ah lead acid battery, which in turn poweres the greenhouse controller and radio. And in a few weeks the relays for lights and pump will be hooked up. And there is still some code changes to be made to the gateway and the controller node, but all that will be later. For now, let’s see how this off-grid setup holds up.
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[UPDATE 5 JULY 2011] After checking the results of about a month of consecutive monitoring and controlling, we found that it requires a bit of tweaking here and there, but mostly functions as hoped. However, the goal is to have the greenhouse controller powered off grid by solar cells. That has been tested and works fine, except that the XBee radio we use, currently consumes too much power and will eventually drain the battery slowly but surely over the period of a few weeks. To battle that, we are reading up on our XBee skills and implementing some changes in configuration and code to improve the radio’s power consumption by having it go to sleep when not transmitting.

We hope to be back online somewhere next week.
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A brief update to tell you that the greenhouse is currently offline for maintenance. It has been running non-stop for about a month and we are evaluating the data we gathered and are planning to add some more functionality. More specifically: the ability to tune the threshold values for the actuators via a webpage (the moisture level before the pump switches on, desired amount of light per day, etc).

This will require us to learn a bit more about the Xbee radio’s and the API protocol. We’ll keep you posted!

Until we are back, why not read a good book about the subject of building wireless sensor networks (See all Networks Books)? We just received this great book and absolutely love it. It is such a great resource for everything Xbee/Zigbee related. There is a lot to be found online, but we found that to be sometimes incomplete, very specific, etc. This book presents you with 8 chapters and 7 projects to build.

Please consider buying this book via our Amazon-affiliate link. It helps pay the bill

To send the messages, the pachube feed is used. Pachube offers a feature called “triggers” that allow the owner of the feed to setup a call to a URL when the value of a datastream meets certain criteria. For example: the greenhouse’s temperature datastream has two triggers setup: one if the temperature gets below 10C and one if the temperature gets above 30C. When those criteria are met, a PHP script is called. The script reads the data values and sends a tweet on behalf of @SageBySindono

In its current form, this is pretty basic and we consider it to be a proof-of-concept. But, if succesful, future versions could be more elaborate. A lot can be done within the PHP scripts with the values from the datastream.

We plan to do a writeup on how to twitter values from your sensors using Pachube triggers somewhere in the near future, so you too can setup something similar for your project.

Until then, follow @SageBySindono to see what is possible.

But, we did not really like the name very much, so we decided to come up with a new one. An acronym, because we love acronyms:

S.A.G.E. you know, from the herb sage… which could grow inside the greenhouse.. I’m sure you get it

It stands for Sindono’s Arduino Greenhouse Environment. Nice eh?

And so, from now on, we’ll call this thing SAGE. And with the start of the new name, we also want to start with sharing more of the sources of the project with you, such as Arduino sketches, hardware setup and settings, php code (in development in order to send twitter messages from the Arduino).

So, stay tuned for more to come from SAGE!

When chaining that many TLC’s together on a breadboard, according to the way described in the Arduino library for the TLC5940 (see Hardware Setup section), the chain does not perform correctly. TLC 6 lights the attached LEDs much less bright than TLC’s 1-5 and number 7 does not light up at all. Also, when TLC5 is “active”, some LED’s connected to TLC’s 6 and 7 show erratic flickering.

The Arduino playground page for TLC5940 is not very helpful in this as to why this happens, so I went to the forums and started a new thread. An interesting answer was posted by Mike Cook (aka Grumpy_Mike) on the forums. According to his knowledgable comments, I need to add de-coupling capacitors to each IC in order to smooth out the fluctuations on the VCC line. He has written a clear tutorial on the de-coupling subject on his website. Also, the Easy Electrons series by Jean-Claude Wippler (JeeLabs.org) is very helpful for general knowledge on understanding components and circuits (check out his cafe section), and this post in particular for understanding de-coupling capacitors.

Unfortunately, I do not have 7 condensators capacitors with equal values in my toolbox. However, I did have 3x 10uF and 4x 100uF, so I added that and guess what? Different results, promising results! All TLC’s now light up, more or less uncontrollably, but the improvement is that all TLC’s seem to light up LED’s with equal brightness. Next up: getting equal capacitors for all IC’s and try again.

Other tips Mike gave are: Getting separate power lines to each TLC, instead of chaining the VCC and GND lines, and plave the TLC as close together as possible (in order to keep (signal) lines as short as possible).

To be continued…

Some time ago I read about the Texas Instruments TLC5940 LED driver IC. It features 16 channels of PWM control with a 12-bit resolution, which means you can control 16 LED’s per chip and dim each LED form off to fully lit in 4096 steps. Or, you could use those channels to control RGB LED’s in which case you could address 5 RGB LED’s per IC and have one channel to spare. In addition to this, it is quite easy to daisy-chain multiple TLC5940′s together.

Texas Instruments TLC5940

I ordered a sample from TI to experiment with in combination with an Arduino Uno and with the help of the Arduino Playground I found out how to hook them up and a library to easily address each channel. And before I knew it I was able to get some example code running:

This was exciting! However, doing knight-rider style light-effects on a breadboard is only going to entertain for so long. I have a bunch of (200+) white 5mm LED’s laying around here, which cannot be easily fitted to the breadboard in large quantities, so I decided to finally take the plunge and try to come up with a custom PCB to make a modular PCB that contains one TLC5940 and 16 LED’s and connectors to string multiple units together. And with the help of two great tutorials by SparkFun (“Beginning embedded electronics 8: Eagle Schematics” and “Beginning embedded electronics 9: Eagle PCB Layout“), I designed this schematic and PCB:

Modular 16ch LED driver board schema

Modular-16ch-LED-driver-board-PCB

I had them looked at by an electronics guy at work, who did not see any obvious issues with it, so I decided to order 10 of these from MakePCB.com today. From what I have heard their communication skills are below par, but the PCB’s are of good quality and the costs were lowest I could find with shipping to my address. Now the long wait begins!

Just to be clear: I do not have a background in electrical engineering, I am test engineer by trade. I did not know *anything* about pcb’s apart from what they look like in a device before I started this and regardless of if the PCB’s are completely correct or not: I was able to pick up all this knowledge online and practice with free and often open-source software, making this a very low barrier to entry.

As soon as I have those PCB’s I will solder the components to it, and maybe fix an error here or there, but hopefully show a great result! And of course, once the design has proven to be correct and functional, I will share them here with you!

To Be Continued…

Very exciting stuff! And to get you started quickly: there is a tutorial section with an example to log sensor-data using an Arduino and ethershield.

Looks like an interesting service to use with the greenhouse monitor!

The measurement unit contains the sensors for temperature, ambient light and soil moisture level and is measuring the environment of a basil plant in the living room. It transmits its data wirelessly to the other Arduino board upstairs, which is connected to the internet by means of an ethernet shield.

I have learned *a lot* about the Xbee radio’s and how to set them up, thanks to a great community. So, I want to share more knowledge at a later stage. But for now, I just want to see what the (near) realtime data looks like embedded on this site. The bar on the right on this website shows the temperature, light and moisture graphs (below the twitter stream). Below is an interactive graph for the temperature measurements.

Temperature (ambient light and moisture are not visualized here yet):

See all the feed data at: pachube.com/feeds/11261

I got some great help from Hardik Pandya (http://prospekts.wordpress.com/) and eventually with the Xbee-api code (http://code.google.com/p/xbee-api/) I was able to get an example running, sending a value read from an input pin to the receiving Xbee.

With both Xbee’s running in API mode, a mesh network can be built using many more xbee’s exchanging data.

In the near future I will post more info on how I got it setup as it took me a while myself to get things going.