Wednesday, February 22, 2012

PCB, easy as 123!

At last! The printed circuit board that I designed has arrived for my fermentation chamber thermostat.  Actually, I received it just over a week ago but haven't had a chance to document it.  I was very happy to see a package from BatchPCB in the mail.  Even more so to find it contained a second bonus board (not sure why, but it will be nice to have another one if when I ruin the first one.)

As expected, I did realize some mistakes that I made (shocking... I know) in the design of the board .  I, for some reason, didn't allow access to the microcontroller chip for reprogramming purposes.  So I had to add another header on the board for that.   I did this by drilling small holes in the pattern of the header into the PCB. Then after placing the header into the holes, I soldered small stretches of 30 gauge wire between the desired contacts.  There's nothing like going at your new prized possession with some power tools to get the blood flowing!

I also decided that the placement of the LED's on the board were too high (with respect to the faceplate of the case), I resolved this issue by placing the headers and LED's onto the back side of the PCB and then installing the board face-down inside the case.  This moved the LED's further down on the faceplate.

So after performing all the necessary changes, I soldered the remainder of the components.  I still have to test out all of the connections before I can add power and start using troubleshooting it, but all the parts are there... and I'm pretty happy about it!  Here's what it looks like:

You can see the little blue "jumper" wires just below the chip that I added to connect the new ICP (In-Circuit Programmer) header (all of the headers are shown in the top pic, what used to be the backside of the board).  I took these pictures before I cleaned the excess flux off of the board, which makes the board look even more sloppy (it certainly doesn't need any extra help).  Flux is a chemical that aids in the soldering process, it cleans the corrosion off the metal connections and allows the liquid solder to cling to the pads and wires.  However, it leaves a sloppy and dirty looking board afterwards.  The good news is that it comes right off with a little rubbing alcohol.

You'll notice that two of the corners of the board have been beveled.  This is so I can slide the board as close to the edge of the case as possible without interfering with the screw holes for the lid of the case. I'll add another post soon of how everything fits in the case.


Tuesday, February 7, 2012


I know you guys are just dying for more information about microcontrollers.  Well, I've just so happen to come across this presentation on the internet (I'm seeing some potential in this...).
This guy will tell you everything that you want to know about microcontrollers and more (probably WAY more).  It's a good presentation regardless of your existing knowledge of the subject.  If you'd like, you can just listen to parts of it , there are bookmarks on the left side so you can jump to different sections to get some overviews.

Check out the link here.

But more importantly, check out that guy's voice!  It's like SILK!   I'd listen to him describe the procession of an episode of food poisoning. Which is probably a good thing since, for some of you, this presentation will be equivocal to such a description.


Thursday, February 2, 2012

Picture Time!

Welcome to February!  It seems odd that we are already in our second month of 2012.

I've been making pretty good progress lately on my thermostat, however, most of the work done has been updating the software embedded within the microcontroller, which makes it hard to convey physical progress.  I plan on creating and posting a video of the user interface, which should give a pretty good idea of the usability of the thermostat.

I've had this hardware setup for a while now, but haven't really given any indication of it other than a theoretical description of it.  So I thought I'd post a few pics to give you a visual idea of what it is I spend so much time aimlessly staring at with glazed eyes.

This first picture is the main "board" with the complete system attached.  And by board, I mean a scrap piece of wood I had sitting around the garage that I painted.  It just seemed to be a good way to keep all the parts together on a movable object.

The parts along the bottom of the board are components of the user-interface; the Menu, Up and Down buttons are on the bottom left and the LCD screen on the bottom right.
You can see the microcontroller chip in the middle of the white breadboard, the other electronic components are spread out between the remainder of the white breadboard and the blue breadboard at the top-center of the picture.
The PC board in the center of the picture with the USB cable is the PICKit2 board.  This board creates an interface between the microcontroller (the PIC) and my PC.  It allows me to upload the program to the PIC, start, stop, and reset the program as well as may other debug functions.

This next picture is the AC/DC power converter.  This converts the 120 volts of AC (alternating current) power from your outlet to 5 volts of DC (direct current) power.  This is similar to what you will see if you were to take apart one of the big heavy outlet blocks that power the majority of your electronic devices.

And finally, I snapped a picture of all the components as well as the box (seen in the bottom left corner of the picture) that all of this needs to fit in to.

All I need is a shoe horn and a hammer and it will fit just fine!

I'll try and get a video out soon to give you an indication of how the user interface works.