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15938Re: [tracker2] Small Affordable Self-Contained APRS?

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  • Scott Miller
    Sep 26, 2013
      Might have some first prototypes in a few weeks.  Production is probably months away.  I'm doing a lot of development work on the T3 code right now, but I've already run out of code space - I can only keep working on the new code while I've got other functions (like Garmin support) excluded.  Prior to a new release it's going to have to either get slimmed down quite a bit through optimization (always a painful and time-consuming task) or I'll need to start separating out feature sets.

      I'm also considering a switch to another Coldfire v1 series MCU that has 256 KB of flash.  It's also got some handy on-chip analog components, including op amps, that would reduce the component count for a complete tracker.  I'm laying out a demo board, but I'm anticipating some headaches getting the bootloader ported to the new chip.  In the long run, Freescale's ARM-based Kinetis line is looking like a more viable option.  In either case, the parts I want aren't readily available in production quantities yet.

      I've forked the OTUSB/T3 family from the T2 code base, which has given me some freedom in cleaning up the code.  Lots of architectural changes are in the works that will make it easier to maintain and improve the code.

      The biggest new addition is a user interface module.  The character LCD support in the T2 and OT1+ was very primitive and ad hoc, shoehorned into the APRS parser and built for only one display.  The new architecture provides an API that the display manager and a new historian module can use to tap into the APRS data.  When complete, it'll be relatively easy to support new display formats.

      At the moment, the interface I'm working with most is a 128x64 monochrome display with a D-pad type 5-way switch.  It's the same resolution used by the YagTracker, and consequently looks somewhat similar.  The prototypes I'm working with aren't big dashboard type displays, though - they're small chip-on-glass OLEDs.  The smallest is 0.96" diagonal, and those are cheap enough that I can see them being used for configuration and status information on even entry-level trackers, including the magmount tracker that this thread is supposed to be about.  The 1.3" size is easier to read for a handheld device.  Both are about 1/16" thick, very high contrast, and take very little power.  For dashboard use, it's trivial to swap it out for a larger 128x64 LCD - I've written low-level drivers for a couple already.

      Keep in mind that I can't make any promises about how much of this will make it into the standard T3 firmware release.  Space is tight, and adding a configuration menu to the UI is going to eat up even more space.  Also, the OLEDs aren't easily wired into existing trackers.  I see this work potentially going in three directions - new T3 derivatives with targeted feature sets (e.g., a handheld tracker that doesn't need Garmin FMI support), a T3 successor based on a bigger MCU, and maybe an add-on display head for older devices.

      Then there's the new Bluetooth support, and experimentation with cheap 1-watt UHF transceivers.  Also, I got bored on Monday morning and wrote some code to drive WS2812 addressable RGB LED strings from the T3's keyboard port.  No idea what use that might have, unless you need your tracker to provide mood lighting or run a billboard display.


      On 9/21/2013 6:34 AM, qrv@... wrote:


      Not a huge rush.

      Are you thinking weeks or months?

      Will the price point be under or over $150?

      How would it be set for tracking vs sleep? 24/7 bursts then
      rest or detect motion or a timer?

      Do you have a pic of what it might look like?


      > What's your time frame? I'm working on a couple of things that might be
      > useful for this. In particular, I'm working on a magnetic mount tracker
      > based on the MX145. The goal is to have the tracker, GPS, transmitter,
      > and about 10 days of Li-ion batteries (30% tracking, 70% sleep mode) in
      > a 4" diameter dome with a 1/4 wave antenna on the top.
      > Scott
      > On 9/20/2013 4:22 PM, qrv@... wrote:
      >> Is this everything that I need?
      >> Argent Data Systems
      >> 1. Tracker3 Model T3-Mini $40.00
      >> 2. SRB MX145 Transmitter $69.50
      >> 3. GPS
      >> 4. Antenna
      >> 5. Connecting cables


      Thanks! & 73, KD4E.com

      David Colburn - Nevils, Georgia USA

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