How To Make Almost Anything Class
Lassiter's WEEK #5 Assignment
The assignment for this week was to mill a "Hello World" board , stuff it and program it.
I have milled many a board to date, but never one that worked. Or at least, they disappear
before I can test them so I've never known whether or not they worked. Plus which, historically,
I had to make my own cables, and have not yet succeeded in making a working cable. So the fact
that cables were provided for this week's assignment was most encouraging.
Downloaded hello.sch, hello.brd, and hello.asm from fab.cba.mit.edu/fab page. Opened hello.sch in
Eagle program. Processed the board such that layers 1, 17 and 18 were selected and by doing so
created a hello.cmp file. Opened hello.cmp in the cam tool and contoured the boundaries, rastered
the interior and created my hello.rml file.
Milled the file on the Modela MDX20 machine with no difficulty. I cheated and used the PHM machine
and did not experience the same difficulties as the rest of the class. Seems the machine in the
laser cutter space is having trouble-- bed uneven. Have ordered a new Modela for the laser cutter
Stuffing went fine, Neil's trick of putting solder on the copper leads first before attaching the
component made the process go very very quickly (compared to what I am used to anyway!). Had
some troubles with cables for programming. Seems the good cables were never made, so we had to hunt
around and make cables. Shani made a sucessful pair of cables so we used hers.
Opened rx.py to get the program running. After attaching both cables-- one for power, one
for programming, I attached the 8 pin clip to the microprocessor. After many attempts to hold the
clip perfectly on top of the leads on the microprocessor, I typed the avrdude in circuit programmer code
into the linux shell,hit return, and "Hello World" typed out nicely on the computer screen in rx.py.
I decided to changethe program to read "Voila! Success!". To do so I had to open the hello.asm file (Ithink it was that
file) in Kwrite, change the programmed text to be "Voila! Success!", saved the file, and then
reprogrammed the board via cable and avr language to read "Voila! Success". And succeed I did.
What a relief!
Here is a picture of my Voila! board, and of an efe board I milled this week as well.
Hello/Voila and Efe boards.
UPDATE on Final Project
This week I found the sonar board files on the Norway site. I milled the boards and
had a bit of a problem with the Receiver board-- Ithink the end mill on the Modela broke
about 2/3rds of the way through. The Transmitter board milled perfectly. I am concerned that
the copper traces on the boards are too thin/small. The are quite small, and in looking closely at the
surface of the boards you can see little gaps in the copper traces. Which I suspect is not a good
thing-- might not allow electricity to pass. Will need to check with more experienced folk. Also,
not sure I processed the board correctly. I found lots of different layering options when I
set the cmp file up, and I could easily have not selected the right layers. I choose the same as for
Hello World-- 1, 17, 18-- and this may require something somewhat different.
I am wondering if the unidentified pads on the circuit boards are the places that one connects
the ultrasonic devices. I'm betting yes. also, how to power them? Need to look into batteries.
This just in from Yvgne:
The sender were powered from battery, but the receiver used a adjustable
power supply that we took from Troms¿ University College. Both boards used
the "large" power connectors. The ultrasonic parts were soldered directly
on the circuit board, after drilling a hole for the pins in the soldering
pads. Dag HŒkon made a library part to Eagle for making the pads, but i'm
not sure where to get that file. You might be able to open the board file
and copy it from there...or send a email directly to Dag HŒkon asking for
it. If you find a smart way for connecting the ultrasonic parts temporarly
to the boards (without soldering) please let us know...
I'll try to take some picture of what we have/had, it should not be to
hard to get that.
We have quite a lot of things that has to be done before the ultrasonic
rangeing is ok. The first/biggest problem is to syncronize the start of
the ultrasonic burst from the transmitter with the timer in the receiver
to get the correct flight time through the air. This is very important to
be able to calculate the range correctly, and we have been thinking about
using infrared light to transmitt the syncronizing pulse (or request from
receiver to transmitter about starting sending the ultrasonic burst). I
think that there was some project using infrared light in Boston, but I
have checked this out yet.
Our progress on LPS has not been to great lately. Still, I'm working
mostly with the assambly programming and Dag HŒkon mostly with the
electronics (and the board and schematic).
Keep us posted about you project!
As for the solenoid/linear motor-- no progress this week, other than to determine that this is
in fact what I want to try to make and use for the heart. I will try to get the parts and get
started on a motor this week.
Also will design a prototype for the telescoping mechanism this week.
TX13 transmitter board and RX1 reciever board from Norway.