I'm writing my own Android app for TeleBT that would be optimized for a small
screen format, and I'm looking for documentation on the TeleBT Data Packets.
In particular I need to know what data strings are sent from AltosDroid (or
any app) to the TeleBT module. I'm able to read and process the data
packets that TeleBT sends out over BT, but I haven't seen any documentation
on communication in the other direction. I've noticed that TeleBT forgets
it's 70cm frequency setting when it gets powered down, and I need to be
able to tell it which frequency to use. Other uplink command documentation
could be useful as well.
I'm replying to this via email instead of privately on TRF because I
think the answers are of general interest to our customers, and thus I
want to CC our mailing list. Hope you don't mind!
> I noticed that when I accessed the EM via AltosUI, the battery voltage
> reported is about .5 volt lower than the actual voltage of the lipo.
There are two things going on. The first is that EasyMini v1.0 units
with purple circuit boards like yours have a design glitch, in that the
voltage measurement is actually at the input of the LDO *after* a
blocking diode, not on the battery itself. This means the reading will
always be a fraction of a volt down from what you read at the battery
terminals. We corrected this for the batch currently under assembly
that will be on green circuit boards. For some reason, we failed to
bump the version number, so both purple and green boards will be marked
v1.0 but purple have the bug and green are good. [sigh]
The second issue is that we aren't sure we got the ADC conversion
coefficients right on EasyMini. Keith will investigate this as soon as
the new (green) batch of boards arrives, to make sure we're reporting
the right voltage on the corrected board design. That may result in a
firmware bump, we'll report if so.
> Second (disconnected from Altos), when I turn on the EM, it reports
> Startup, Pad, and then continuity. It does not report the battery
> voltage. So, on the pad, when the EM is powered up, I won't know what
> the voltage state of the lipo is?
> Is there a firmware update that will provide a report of the lipo
Great question. Just hasn't come up before since all our other flight
computers have radio telemetry. Keith says he'll add voltage reporting
to the EasyMini startup beeping. We'll report when that's done and new
firmware is available. The plan is to report two digits so you get
tenths of volts.
> On your next version of the EM, you might consider (if possible
> without increasing power consumption too much) an increase in audio
> volume. As it is right now, the EM beeps away for over 2.5 hours on a
> 110mah lipo..... nice! Still had a reading of 3.90 volts on the lipo
> at that time.
The audio volume is constrained by the combination of our choice of
beeper and the fact that we're operating at 3.3 volts. We use the same
beeper on all our products that have one because it's the best I've been
able to find so far. The same beeper is louder on 5V, but that doesn't
help us. I haven't found a small beeper that's louder, but I do check
our suppliers from time to time hoping something better comes along! If
anyone knows of a better beeper, by all means let me know!
Hope this helps.
Bdale Garbee <bdale(a)gag.com> writes:
> Comment: Hi guys, I have to say, your work looks very
> impressive. Great work!
> In regards to your 850mAh battery, any chance that a more narrow one
> can be substituted or in the works? I have a 29mm minimum diameter
> project right now and it seems that this battery is a bit big for my
I'm going to CC this reply to our mailing list since I suspect the
answer may be of general interest.
You are correct that our "new" nominal 850mAh cells will work great in
38mm and bigger airframes, but won't fit in a 29mm coupler.
Now that we're having flight batteries custom made specifically for our
products, we chose to start with the "850mAh" cells since that's our
default battery for flight computers, and it's also what we use in
TeleBT, so we felt comfortable meeting the suppliers minimum order
quantity for a custom battery in this size.
I'm pleased to report that we're happy enough with the 850mAh cells to
have placed an order for a second cell size. These will be 160mAh
nominal in a 5x20x24mm size that should work great for you. I've run
TeleMetrum boards on 110mAh batteries in several smaller airframes in
the past with great success, so this is definitely enough battery for
Lead time on these is about a month, so I would expect to have them and
be able to add them to the store in early April.
If you need something sooner than that, we have notes on our web site
about how to modify the LiPo cells sold by sparkfun.com to remove the
protection circuit board. They sell both 110mAh and 400mAh cells that
could be made to work for you with this modification:
> I'm looking to use the Telemetrum to record telemetry as well as
> provide GPS tracking since it is likely going to be difficult to track
I hope this info helps, and best of luck on your project!