The Box: Prototyping

So “The Box” project is back, taking on a less ambitious form this time. I’m not going to try and cram every part I have into a box. It’s just going to be a simple temperature and humidity monitor with a clock and some LEDs. It’s nothing fancy, but I’m hoping I end up with a polished final product.IMG_0826I’ve begun prototyping all of the elements of the project together and I think I have a solid base right now. Let me walk through how the prototype currently works.

IMG_0831The system greets you when it’s first powered on. There is actually a reason for this which will be explained shortly.
IMG_0832This is the main screen. The clock can be toggled between 12 and 24 hour formats. The bottom line alternates between the temperature and humidity readings every three seconds.IMG_0835There’s the button to toggle the clock. The system is powered by a 9v power adapter into a 5v regulator. The brains is an Atmega328p microcontroller.IMG_0834Those two perfboards have the temperature/humidity sensor and the real time clock. Oh look, some LEDs!

The LEDs go back and forth signalling a complete second. It’s done using delays which provides a break for the LCD and sensor updating. While the LEDs are going back and forth, it isn’t actually using the RTC. It’s simply delayed so that a cycle back and forth takes a second.  This takes us to the reasoning for the power on screen with the “Hi”. What’s actually going on is there’s a delay so that you can always read the “Hi”, then it waits for the next second change by the RTC. This process syncs the start of the program with the start of a clock second. That way, every time the program loops back to the beginning, it starts at the top of a second since each loop of the program takes a second to complete.

Check out this video to see the prototype in action:


Temperature and Humidity Monitor: Update 1.1.2

Yesterday, I posted about doing over the soldering for the DHT22 temperature/humidity sensor. In the post, I mentioned that the temperature scale appeared to top out at 30ºC. I’m not sure what went wrong, but when I went to fix it, it wasn’t an issue. While I was in Visual Studio, I did a little tinkering and added something new.

new1I removed the status bar that showed the current time and the timer telling you how long the historic values were true. I removed the current time because it was a waste of space, and I removed the historic value timer because it didn’t make a lot of sense with the new pause button. When you click the pause button, it stops requesting data from the Arduino until you click it again.new2The full log also gets a note mentioning the pause if you do decide to pause the logging.

The last minor change was adding a link to the Device Manager how-to window in the manual connection screen. You can get the download on the Temperature & Humidity Monitor project page.

Temperature/Humidity Sensor Soldered. Again.

It’s been a while since I touched the Temperature & Humidity Monitor project. I’ve been thinking about making it a standalone device, combining it with the real time clock and LCD I have sitting around.

IMG_0810I decided to transfer the sensor onto a new board. I cut a piece of perfboard and soldered it on, trying to be neater than last time. IMG_0812Somewhat unnecessary layout but I think it looks nice.testI tested it and it worked fine. This time, I put my soldering iron near it and tried to get the temperature to rise. I’ve never experimented with it like this so I just found out that the graph doesn’t rise past 30ºC. I’ll probably go back in and fix that.

A part of me would be bothered if I couldn’t get the sensor to work with the Visual Basic program once it becomes part of a standalone project without the Arduino board. I haven’t tried making a serial connection with an Atmega328 chip by itself. For now, the sensor would probably not be permanently mounted to anything so I can always plug it back into an Arduino and work on the VB program if I chose to.

Temperature and Humidity Sensor Soldered

With the temperature and humidity monitor Visual Basic program perfectly functional, I wanted to finally package up the hardware into a neat little module I can plug and unplug easily from the Arduino, even if it’s in use for another project. I had tried soldering on a perfboard using the chisel tip that came with my iron but it was too big for me to handle. I went to Sayal today and picked up a thin conical tip (ST7) and it has worked out great, though I can use more practice.
IMG_0570I was trying to make connections between the individual pads using blobs of solder, which was the problem using the larger chisel tip. I couldn’t get the solder to flow over to another pad so I ended up bending the excess wire and soldering them together. It’s a bit of a mess but at least it works. My soldering training was on printed circuits so I just mindlessly soldered components to the board.IMG_0575The top half of the board was scrapped because it was part of my attempt to solder the 7-segment displays which did not go well at all. I plan on removing more of the board so I can make the module even smaller.IMG_0572The only wire I have are black and red so it’s kind of confusing to have two black wires coming out of the board. One is ground and the other is the signal. To remedy that issue, I cut the wires relatively short and am relying on these jumper wires to lengthen and color code them.

In addition to the iron tip, I picked up a couple of mini perfboards that I hope to find use for soon. I also picked up a crimping tool (which came with a bunch of random things like electrical tape and a voltage tester that I’ll never use) and some terminals. A PLC trainer revisit is in the works. Details on that will come soon.

Thanks for reading!

Temperature and Humidity Monitor: Save your data


Version 1.1.1 of the Temperature and Humidity Monitor is up! This update includes ways to save your data. You can now export the two graphs individually as an image. I’ve also added a new log that records all values continuously (unless the log is cleared for whatever reason). You can export the log as a text file.

Get the new version on the Temperature and Humidity Monitor page!