OUTPUT DEVICES
WEEK 10
- Add an output device to a microcontroller board you've designed and program it to do something
TWO DC MOTORS
For this assignment I have done an H Bridge board, because o my final project, I didn't know how it's going to be, but clearly it will need motors. I take Gonzalo Siu's board as an example of a board that works with a FABKIT or an Arduino as an external microcontroller and can function for DC motors and stepper motors. So I decided to redraw it more symmetrical to fit the needs of my final project. I find the four LED indicators quite useful.
- EAGLE HBRIDGE SCHEMATIC
- EAGLE HBRIDGE BOARD
When the schematics and board plans were finished, I exported them as a png monochrome image, but I modified it in Photoshop and erased six pads that I assumed would not serve me because they were not connected to any vias.
I mill the board with the Modela MDX, the first attempt did not turn out as expected, a partner kicked the extension plug inadvertently and the milling process stopped, so I had to make another attempt. The sencond one was successful an then I soldered the components.
Unfortunately the pads that I deleted, reduced stability to the connections, which began to break, so I had to put hot silicone to fix them and prevent them from breaking completely.
The next thing to do was to program a simple task for the DC motors, I used Arduino IDE to program and upload de code to the fabkit. I wanted the motors to spin first one to the right, then to the left, then the second one to the right, an then to the left.
- ARDUINO HBRIDGE
When the FABKIT was programmed, I made the connections, first to the fabduino (taking into account the correct order of the pins), then conect the FABKIT to the computer with the FTDI cable, then conected the DC motor to the H Bridge and finally the H Bridge to the power source. I wanted to use a 9v battery as a power source, however the power was not enough, so I had to change to a source that would allow greater voltage, finally I used 12v and 3 amp.
After conecting everything, it still not worked and the H Brige board and the Fabduino board began to warm, I had mistaken the connection of the Vcc and the Gnd and was generating a short circuit. I just corrected the connection and both engines started to work.
xmottex@gmail.com
