After many months of waiting and more than a few weeks of forgetting I had help Kickstart it, a box was on my front porch Monday about lunch time. I had the grand unboxing of it. I am here to share my first bit of time spent with it.
Now that was over a week ago, hopefully I will pry away some time to start working with it here in the VERY NEAR future.
Early on in my adventures in the Arduino / micro controller world one of my goals has been to usher an idea from paper, to breadboard, to protoboard, to real PCB board. After a long night of soldering, I decided to take a break and start to post my adventure.
I learned early start simple and build on what you know. In that vein I took the idea of making digital dice. To date I am up to the proto-board phase. I am making an actual “digital die” I can give as presents for this Christmas season. By next year I will have time to figure out the CAD software I will need.
I had an idea how to start the project, this will be simple. I grabbed my Arduino Uno, 7 LEDs, and my breadboard. 7 lights, 7 pins, and away I went. After a giggle of joy over seeing it work, I stared at it wondering how I was going to make a box that looked reasonable to fit the Uno. That idea was quickly nixed. In my readings and forum lurkings I had heard of the different chips in the ATmel family of microprocessors. With a little digging I soon found the ATtiny85 which seemed like it would fit the bill I was looking for. Small footprint and just a few pins. Dang, I have 7 LEDs with 7 pins and this little guy sure doesn’t have enough, or does it.
While awaiting my ATtiny order, I used the time to research a little more about this new turn I took (with little foreknowledge save it should work). I also waded through the data sheet for the ATTiny family to find out more of their capabilities. You can find the information here. There is a method to control more than 1 LED pre pin. The method is known as Charliplexing. Here is an example to get you going.
My apologies for a lack of pictures here early on. I was too involved to remember to take any.
With a little more knowledge in hand it is time to draw out how one might control the LEDs. Knowing how a die is made with the numbering scheme as dots we need a total of 5 to replicate what an actual one looks like and how they will light up in turn. With 4 pins I can control the 7 LEDs to make the 6 numbers.
JustNotesv1JPG.jpeg
scheme.jpg
Now that I had my little 85’s in hand I took to the breadboard to see what I could come up with. It took a couple of tries to a) double and triple check my wiring (make sure ground is going to ground!) b) at the same time learning how to program the ATTiny.
So, here is where there is a branch. I am going to take a quick detour on the ATtiny85. The ATT85 is part of the Atmel family of microprocessors. The ATT85 has fewer pins, less memory, and slower than what you find on the Arduino Uno board. None of these are an issue for this project and in all ways a big plus as I want this project to be small in size. There are breakout boards and programming boards one can use to program the ATtiny85 and there is the use-what-you-have-it-works-pretty-darn-well method too. I went with the later of them. Here is one of the sites I researched when planning on how to get my code on the ATTiny85.
The wiring is pretty straight forward, just follow the diagram. If it is your fist time trying this out, the blinking LED exercise if a good one; if for nothing else getting you used to setting up and uploading code to it.
On the right hand side of my breadboard you can see the ATTiny85, wire up and running the die code. In this version I am using a button switch instead of the motion switch.
It works. I have my ATtiny85 programmed with my die code, wired up to the LEDs, and it is working! I have that giddy feeling all over again, but than the sigh. Even if I get a small breadboard it still won’t look quite right. I guess it is time for another plunge and learning experience. That is a good deal of why I started tinkering in this digital world.
I knew what was next, I had to solder it all on some protoboard. You know those green or tan sheets with holes (well some have holes predrilled) that you can solder little parts onto. I made out my list of parts and pulled them all before I began. This hasn’t been your weekend type project. Between family, work, and other of life’s bits it has taken me a few weeks by now. And those boats from China really are slow!). And it has taken me more than one try to get to this point.
This is my first try at a full-on, solder it up type project. I didn’t think I would get it right on the first try, but Oye Vey! It almost worked, but my voltage readings were waaaaaay low by time I measure at the LED pins. Oh well, I will not be deterred and try again.
It is time to move forward, remembering mistakes made, and get it right this time. Before this attempt, I went to a good friend of mine who is an EE and quite the hardware hobbyist. He gave me a couple of quick, and very informative soldering lessons. During my lesson I learned that my lead-free solder was causing me some issues as it takes a higher heat to use and even slightly higher heat to reflow. Before tackling this next part, I was sure to procure some leaded solder and it makes a difference.
The first thing I started to thing about, beyond the predetermined layout for my LEDs, was how to best wire them. My end goal being a manufactured PCB, so why not use this exercise to start to think in that mode. All LEDs have 2 leads, one for ground and one for power. I started by arranging as many LEDs as I could with the ground pin on the outside of the board. This way I can chain them together to create an easy ground path.
The only one I needed to worry about was the inner LED. In its’ case I bent the ground pin over to the main ground path. It reached with some to spare.
Now I started to look at connecting the power for the LEDs. Where I could, for aesthetics, I ran a straight wire on top of the board. This keeps the wire count below down and gives it a nice look (I think).
Working with the back I tried to keep the lines as clean as possible too. The backside is a little more of a challenge.
In a yet another branch, while on my travels, it was noted that the ATtiny13 might work in this case as well. The memory footprint is smaller, but than the sketch for this project isn’t that big to begin with. I ordered a few in one of my bundles. Since I have a socket on the board, it will be easy to test!
I have four pins left to solder and apply power for the big test. That will be tonight. I will be sure and let you know how it goes.
Keep up with my progress over at wrightmac.net I am not done yet. 🙂
BOM (Bill of Materials)
1 Protoboard
1 ATTiny85 (read a little lower for more on this choice)
7 LED, 5mm
1 Motion switch
1 Various 24AWG solid core or stranded wire
1 Soldering iron
So, I am picking up the story a little in the middle, but hopefully you will pick up quickly.
To get up to speed I would suggest you check out where this all started, over at my hackster.io project page. You can also find a weather sensor kit I have put together based on this project over at my Tindie.com store.
A good starting place is here. Yesterday I pulled out a SD card reader I had for my Arduino collection. It was really one of the easier parts of this build. I removed all of the wires from the Uno, mounted up the SD card shield (it is labeled that is uses Pin4, note made), stuck in a card, and fired up an example sketch with the SD.h library. Here is a link to a good SD reference. I am not doing anything fancy, I just want some simple data logging for right now. And boy did this hit the spot.
I did one last test indoors before I set out for the FREEZING night tonight. It is a good night to stress test the gear. The data sheets say the pieces and parts are good the range. The enclosure is what it is as I only need it for testing right now. I am in the processing of reclaiming the shell of an old access point to use as one.
The next morning, today, I went out and it was still running! Now, did it bother to record anything.
And I am happy to report, why yes it did. I had it taking readings once a minute and now have something to start to shift through and see how I want to use it. Not to mention work on finishing the enclosure for it.
I hope you come back and keep up. I have more ideas and branches for this project.
A simple project has run into that infamous scope-creep but in a good way. To that end, I decided to take the little bits and pieces I have scattered on the web and condenses them into one place, a domain I have had sitting around just looking for a purpose and these does seem to be at great one.
This project is for a basic, Arduino based, weather monitoring station. While this project is for indoor use only, one could easily find an appropriate weather proof case; and using battiers or solar power with wireless place it outside. This kit is meant as an introduction to the Arduino platform, using sensors, and a door to a fun world.
Parts needed:
1 x Arduino Uno clone
1 x 25cm micro USB data cable
1 x DHT22 sensor
1 x BMP280 sensor
1 x 5110 84×48 LCD screen
xx x Male to Female Jumper Cables
xx xx Female to female Jumper Cables
2 x 10k resistors – for sensors
1 x 470Ohm resistor – for LCD
Software needed:
Arduino IDE 1.6.x Various Libraries, find links in the docs.
The order of the parts listed below are the order I wired up and tested each part. It makes trouble shooting easier to take each component, wire it up, install the library, load a test sketch, and make sure it works. Nothing is more frustrating than plugging in 14 wires and nothing happening.
Be sure and check your connections. I will admit to pulling an oops and damaging a component by not paying attention to where those pesky Vcc and ground wires were going. If you have issues, check your wiring first. If you have a multimeter, you can also make sure you have continuity and expected voltages.
| DHT22 Pins | Arduino Pins |
|---|---|
| 1 – Vcc | 5v |
| 2 – Signal + 10k | 2 |
| 3 – Open | Open |
| 4 – Gnd | Ground |
The DHT22 is a low-cost, but accurate, digital temperature and humidity sensor. It has a captive humidity sensor and a thermistor for reading the ambient temperature. It is 3-6v tolerant for both the Vcc (power in) and digital signal line (pin 2). The pins are 1 -4, left to right, looking at the front (the grill side).
Arduino pin 2 is used in this sketch, but any other pin could be used.
Here is a link to the DHT22 datasheet.
| BMP280 Pins | Arduino Pins |
|---|---|
| Vcc | 5v |
| Gnd | Ground |
| SCL | A5 |
| SDA | A4 |
| CSB | Open |
| SD0 | High – 0x76 Low – 0x77 |
The BMP280 is a barometric pressure and temperature sensor. It is a sensor with great accuracy. In fact with a little work one can obtain an altimeter reading within +/- 1M the sensors are so accurate. (I haven’t tested that claim yet) It communicates with the Arduino via the I2C interface. The address must be set either high or low as if it is left at default it won’t work. To set the address high (0x76) use a 10k resistor and connect it to power. If you connect it to ground in the same fashion it will use the low address (0x77).
A good troubleshooting tool to use when first working with I2C is an I2C Scanner. There is a copy of it in my github. I have started a cheatsheet list of the devices I have and what addresses they have. Each time I get a new one I will run it against i2c to make sure it works and see what address to use.
Here is a link to the BMP280 datasheet.
And here is the link to the BME280 library used here.
| LCD Pin | Arduino Pin |
|---|---|
| 1 – RST | 12 |
| 2 – CE | 11 |
| 3 – DC | 10 |
| 4 – Dir | 9 |
| 5 -Clk | 8 |
| 6 – Vcc | 3.3v |
| 7 – BL | 7 – with 470Ohm resistor |
| 8 – GND | Ground |
The LCD is based on the old Nokia 5110 LCD screen used in their past phones. It is a decent sreen and easy to find. Its’ display is 48 rows by 84 columns. It has a PCD8544 controller used for all LCD functions. This model uses SPI for its communication with the Arduino. There are other ones out there that use the I2C protocol which only requires 4 pins. There are some different libraries out there too. I used xxx in this project. The basic functions are well-documented and they also have an additional library with graphical functions.
To Do:
Keeping some historical data and being able to graph them over time is a good additional project. One could store the data on an SD card or rely it via wireless. There is a section of code that shows how to output data in a CVS format for later analysis.
The library used is located here.
As of this writing the lastest version of the sketch is 0.6. Check back for updated versions. I have tried to comment the code to make it easy to follow. I know that good comments make it easier to follow along what is happening. And when one is learning this is a good thing.
Launch the Arduino IDE, open up the sketch Weather0.6.ino found in this github. From the Tools, make sure you are working with the right board, both model and serial port used. A quick verify and compile, then upload. If you have not used the Arduino IDE before there are several great tutorials out there. Here is a good starting point for the first timers, head to this Instructable. Launch the Arduino IDE, open the weather sketch.