Tasks -Select and use software for circuit board design.
-Demonstrate workflows used in circuit board design.
-Redraw the echo hello-world board, add (at least) a button and LED (with current-limiting resistor), check the design rules, and make it. Eagle The Software I am going to use for this assignment is Eagle
Eagle (Easily Applicable Graphical Layout Editor) application with schematic capture, printed circuit board (PCB) layout, auto-router and computer-aided manufacturing (CAM) features. ATtiny 44 The microcontroller that we have to work with is ATtiny 44. We have already used it 1 Week ago for the FabISP Library In order to work properly, have to download and use special Libraries. Eagle has a a huge amount of build in libraries that we can use. I my case, I have used Fab Academy Libraries. After you forward the link, you have to choose, the program you are working with and than download the proper Library. Eagle Schematic Eagle has two windows that are used simultaneously to design a board:
-Schematic (.sch) - logical components
-Board Layout (.brd) for the actual board that we mill
Now we are at the Schematic window. Okay first we have to add the needed Library, to do this first click to the Add button, like in the picture below. Now Open the Bibliothek Manager and add the libraly, you have downlaoded before. Attiny44 Now click to the same Add button, that I mentioned before and you will be able to find a fab library, that you have included, with the previous step. Here you can find all needed logical components, that you need. For example ATTiny44 First steps One nice this, that i like about the Eagle is that the pins have names, and you can easily figure out which pins you have to use for Power, GND and programming, the Crystal pins are also highlighted there. To add Labels and connections you have buttons at the left menu side of the window. In order to change the values and names of the components, you have to zoom in to the placed component and right-click on it. Okay this is how my logical pin layot looks like. Crystal I have used 20 Mhz Crystal, and for this specific crystal we need 8 pF Capasitors connected to the ground. Button I have added a button, the buttons requires 10k resistors to limit the curren tflow. Reset Button I have also added a reset button. LED Here we have a LED it requires 499 Ohm resistor again the same, to limit the current flow. According to the DC Forward Current of the datasheet I have to use 499 Resistor Pins These are FTDI and AVRISP pins Power GND Analog Pins I have also mentioned, that we have got two analog pins, that we can use later, so I have made pins for them. I have also added 0Ohm resistor as Jumper, but I have done after I have placed all my components in boardlayout. Okay after we have have finished with the logical connections, we have to play all aour componens in a proper way in Board Layout. to switch the window click circled to the button above. Routes To create the routes, you have got an icon in the bottom-left corner. You can also specify th thickness of the routes above. In my case I have use 0.12 mm. Ground I some cases you can skip the connections of the GND. Make the whole unused space of the board to the GND. To do this, we have first to create a polygon. You can also find it in the bottom-left corner. Fill the GND Fill the unused spaces, we have to click Ratsnest Properties of the GND Than zoom in to the border of the GND, right-click on it and click Properties. Isolation In the Properties we have to change the isolation. Isolation, is the space, between GND and Traces or components. It is recomended to change it according to the width of the routes. 0 Ohm Jumper Okay, here you can clearly see why I have used the 0 Ohm Jumper. After I have placed and connected all components. I had an issue with the Ground. The Gounds were not connected. So i have added the 0 Ohm resistor as a solution. Export Now we have to export out Board Layout as an image. Export Settings These are recomended exporting settings. Exporting Settings Now you have to crop the unnecessary borders from your image. It should look something like this. Now you have to cut out the engraving space sout and save the image for the cutout(Roland). Milling I will not explain how, we have to create a GCode out of the images. It is explained here. After Milling After Soldering Programming Okay now I am going to program my Board with FabISP Okay first of all we have to connect our Board in a proper way.
-MOSI to -MOSI
-MISO to -MISO
-SCK to -SCK
-RESET to -RESET
-GND to -GND
To power my HelloBoard I have used the FTDI cable. Arduino IDE Okay after we conneted everything in a proper way, we have to open ArduinoISP in Arduino IDE Select everything in a proper way. And burn boot loader.
*If you are programmint Attiny 44 at first time, you may have to install the needed library. to do this open this Link and follow the instructions. Text Now we can load a program to our board. I have loaded a Blink example for the testing purposes. We have to load a program to our board using programmer. Done Downloads fab.lbr Schematic Board