Mar 29: output devices
This weeks task was to design your own microcontroller board and add an output device to control something (led, speaker, video, lcd, etc …). I decided to use the video board to make different kind of patterns and output it on a screen.
Schematics and designing in eagle
At first I looked at the board and the components to understand which components it uses and how I should set up my schematic. Then I started to set up the schematic and design the board to my likings.
I had a hard time to find out which components I will need and to label all the different kind of connections. When I had it done I exported it as a png and made the layout in Photoshop for the traces and the lines.
Milling the board with the Roland SRM-20
Then I put the two files into fabmodules to prepare the files for the milling machine and started to mill. I had a problem with the machine first, which at the end was because the drillbit wasnt attached properly and started to move. After I solved it my milling came out really good.
Soldering the Videoboard
Then it was time to solder all the different components on the board. It wasnt really hard because we already soldered a couple of board.
The components I am used are:
1 Resistor 10K
1 Resistor 499
1 Resistor 1K
1 2x3 ftdi Header
2 2x2 ftdi Header
1 IC2 5V
1 Capacitor 1uF
1 xtal 20mHz
Programming the videoboard
This output device can send a video signal to a NTSC monitor via a standard RCA wire. I think this is an 8bit signal. After that I started to programm the board, which wasnt really working.
I tried to load the bootloader but that wasnt working. Back to the soldering table. I fix all my loose soldering and tried to program in the Arduino IDE for the Attiny44 but stupid like I am i connected the GND and the Voltage wrong, so a small cloud of smoke later and my Attiny44 was toasted. Perfect! After that I realised that I made my connection where wrong for the xtal 20 Mhz and also made other connections wrong. So back to the drawingboard. Made my Schematic new and redesigned the board. Lesson learned! After that back to soldering and programming and finally could work with it. I programmed my board over Arduino. I read the microcontroller datasheet which helped me a lot with the pins. Biggest problem was to find a old TV or Beamer to hang the red video cable on it. Until now i tested the sensors and hung it on a Beamer which doesnt worked. So hopefully I find an old tv and can let my programmed pattern run.
Checking the connections again
I tried to hang the board via a red analog video cable to a beamer that I found in the lab. But I think the beamer is to new to adapt it. At first I looked if my input and output really have a good signal but everything looked fine. I will try it later with the old tv I have at home. With this TV i got it to work finally. I forget to make a video of it but I included a small picture where you see my video output ;) At the end it was really just that most of my technologies where to new for the tiny videoboard I made.
Click here to download all the files.