NEAR SPACE
that works well with the UltraLight.
Commit Pin
The last input to the UltraLight is the Commit pin.
The Commit pin was built into the UltraLight because
GPS receivers require time to get their satellite lock. So,
rather than have the UltraLight record data while the
near spacecraft is on the ground waiting for the GPS to
catch up, the Commit pin inhibits the UltraLight from
operating in flight mode. This doesn’t mean the
UltraLight can’t operate experiments on the ground,
however. It just means the UltraLight only performs
actions on the ground that you
desire. If you’re like me, you don’t
want the camera taking lots of
pictures of the launch crew filling the
weather balloon — you want to save
the SD card for pictures in flight.
The UltraLight Commit pin can
be used in at least two ways. To start
with, it can signal the UltraLight to
download mission data when it is
first powered up. Doing so permits
recovery crews to download flight
data in the field without having to
reprogram the UltraLight. If the
Commit pin is missing when the
UltraLight starts up, then the PICAXE
assumes the mission has been
completed and the data is ready to
be downloaded. Use this code to
signal the UltraLight to download
data:
mentioned before, Nuts & Volts readers are allowed to
make their own UltraLight computer. I just ask that no one
make copies to sell. Let me know how your project goes
and I’ll be happy to help readers get their own flight
computer up and running.
Onwards and Upwards,
Your near space guide NV
if pin6 = 1 then Download
To use the Commit pin to inhibit
data collection until closer to launch,
use this code:
Wait_to_Commit:
if pin6 = 0 then
Wait_to_Commit
‘ wait for commit pin to be
pulled
If this code occurs after the
download detection, then the
Commit pin does double-duty of
downloading data and starting data
logging.
THAT’S A WRAP
That completes the UltraLight
flight computer. You now have all the
information needed to construct and
program your own. As I’ve
September 2011 55
