Serial echo

Click on the terminal. Once the window opens type ‘cad’

This is the bit used for machining the part inside de board. (1/64’’ end mill)

We are making the echo board, so you can download it from http://fab.cba.mit.edu/about/fab/ . The one to choose is ‘hello.echo.44.MTA.cad’ since we are using MTA connectors. Don’t forget that everything must be in the same file! After opening cad, look for the file in ‘input’. Then click on ‘cam’ and in ‘output format’ choose ‘modella’. Uncomment ‘dpi=500#high resolution for machining’. Adjust the values: tool diameter=0.0156, #contours=-1, xy and z speed=4 .Click on ‘contour’ to see how it’ll look like, and ‘move’ to adjust the height of the bit. Once it is ready, click on ‘send to machine’.

Now, wait until the 1/64’’ bit finishes its work.

This is the bit used for the contour of the board (1/32’’ end mill)

This time, uncomment ‘cad function = frame’ and ‘z = -.065’. Adjust the values: tool diameter=0.0312, #contours=1, xy and z speed=0.5.Click on ‘contour’ to see how it’ll look like, and ‘move’ to adjust the height of the bit. Once it is ready, click on ‘send to machine’.

Now, wait until the 1/32’’ bit finishes its work.

It is ready to be soldered. After getting all the items (components and tools), it is recommended to stick the board on the table to avoid it moves.

I think this part requires patience. You have to be very careful when soldering the parts. Check that the line in the diode and the LED are in

the proper direction, and the 4-pin MTA connector too!

To program you have to download ‘hello.echo.44.MTA.asm’. Remember to save everything in the same file!! Open the terminal and get into the folder where all files are located

Once you have the .asm, you have to change it to .hex. Like below, you would type ‘gavrasm hello.echo.44.MTA.asm’

Then send power to the PCB. In my case , it was ‘python rx.py /dev/ttyS0 9600’

Fro the crystal (resonator) you will have to type this ‘avrdude –p t44 –c bsd –U lfuse:w:0x7E:m

Then, send the program typing this ‘avrdude –p t44 –c bsd –U flash:w:hello.echo.44.MTA.hex’

Finally, to see if it really works, you type ‘python term.py /dev/ttyS0 9600’.

You MUST check that the serial cable is working properly!. Sometimes I thought me PCB wasn’t working. Then, we realized it was the cable. So, how does this work? When you type what is above, another window will open. Press any character form the keypad and the LED will turn

on.

This board is the dasa.MTA. This board is used as a voltage limiter. The process to machine this board is completely the same as the others. You can find the file (dasa.MTA.cad) in http://fab.cba.mit.edu/about/fab/ .

External power supply

serial AMP MTA plug <-> DB9F cable (wire side view)

5-pin AMP connector to another 5-pin AMP

5-pin AMP to a DB-9 female

Connection