loading its data, the program waits for
the Launch Commit pin to be pulled.
So, after programming the BFC to
download data, switch the serial
cable, and start a terminal program (I
use Tera Terminal to download data).
Tera Terminal is a free communications program available over the Internet
teraterm.html. Before starting Tera
Terminal, you’ll need a text file to save
the data. So, create a near space directory with subdirectories for each of your
missions. Use Notepad to write the
name of the mission into a new text document and save the file in its mission
directory. When you start Tera Terminal,
you’ll need to make these changes to
the program’s default settings. First, after
starting Tera Terminal, a pop-up screen
asks for information about the connection it will use. Select Serial Port and
click on the com port you’ll download
data over. Click on the OK button. Next,
click on SETUP at the top of the
program. In the drop down menu, select
SERIAL PORT and select a Baud Rate of
2400. Click the OK button to close.
Next click FILE and then click Log in the
drop down menu. Navigate to the text
file you want to save the downloaded
data into. Don’t check the Append
option. Close the window and get ready
to download the data.
Now, pull the Launch Commit pin
out and watch the data as it downloads.
At the end of the recorded data, click
on FILE and then click on Disconnect.
This closes the text file your data has
been saved in. You’ll still have to edit
the downloaded data slightly because
either Tera Terminal or Notepad (I don’t
know which yet) is ignoring some of the
formatting commands in the downloading code. But since the file contains a
maximum of 1 kb of data, the editing
goes pretty fast. The resulting file is
comma delimited and can be imported
directly into Excel for processing.
In the text file, each sensor value
is separated by a comma and there’s a
carriage return (CR) and Line Feed
(LF) after each block of data. So, for
example, if the BFC recorded data
from three sensors, NoADC is set to 3
and the downloaded data should be
formatted like this.
Rec, ADC-0, ADC-1, ADC-2, ADC- 3
1, 124, 89,250
2, 123, 90,250
3, 122, 91,250
But, as I said, you’ll still have to edit
the file slightly to whip it into shape.
By using the programs in this
month’s column, you can test your
BFC’s ADC and EEPROM by connecting some of the analog channels to
ground and the others to +5V with a
10K resistor. You must use a resistor to
do this, if you short the ADC inputs
with a wire, you’ll damage the ADC.
Well, that’s it for this month. Next
time, I’ll have more on BalloonSats
and my experiments with PongSats.
You can begin reading about
PongSats at the JP Aerospace website
Onwards and Upwards,
Your Near Space Guide NV
November 2006 107