[aprssig] Argent Tracker4

Scott Miller scott at opentrac.org
Wed Mar 14 13:43:23 EDT 2018

No wired Ethernet in this version, I'm afraid.  I chose the WiFi module 
to cover a few different projects and it's running in network 
co-processor mode, with the bulk of the TCP stack on the module itself, 
and there's no direct wired equivalent.  I've tried to keep my 
application code roughly in line with the Berkeley Sockets API to make 
it easier to port later on but it'll still take a lot of effort to 
change it.  I'm putting a lot of work into making sure it handles 
failures gracefully, though, and it'll reconnect if the connection is 

I might still try to squeeze in a couple of on-board GPIOs for 
convenience, but yeah, Modbus is going to cover most of that.  That 
includes radio power control.  The T2 had a pretty big solid state relay 
in it that very few people used, and the T3 had a smaller one but it 
still added cost for a feature that most people didn't need. Letting the 
user plumb in whatever relays they want via Modbus adds more 
flexibility, and I can't buy bare relays as cheap as you can get a dual 
relay board from China.


On 3/14/2018 10:12 AM, Brad Heaton wrote:
> Wired ethernet?  I have found that even using business grade access-points Wi-Fi isn't nearly as reliable as simply plugging it into the network.
> I was going to say GPIO but it looks like the ModBus RTU will cover anything GPIO can do without risking the CPU.
> -Brad
> -----Original Message-----
> From: aprssig [mailto:aprssig-bounces at tapr.org] On Behalf Of Scott Miller
> Sent: Tuesday, March 13, 2018 4:32 PM
> To: TAPR APRS Mailing List <aprssig at tapr.org>
> Subject: [aprssig] Argent Tracker4
> [External Email]
> I swore I was going to name my next tracker something more creative, but I'm better at programming than marketing, and I think the Tracker4 name is going to stick...
> In any case, it's close to being ready for production.  It's been on the back burner for a while with the ADS-SR2 repeater taking up so much development time but the T3 has been unavailable for a while since we ran out of enclosures and the T4 is far enough along that I'm moving it up rather than ordering more parts for the aging T3.
> The most obvious change with the T4 is WiFi support.  It still has USB and the command shell has been improved, but the easiest way to configure it is with a web browser.  It has a responsive web interface that works well on a desktop, tablet, or smart phone. It'll also act as a standalone IGate, and the shell is accessible via telnet.
> Instead of the T3's primitive scripting system, it has a complete BASIC interpreter with some APRS-specific functions to make it easy to automate actions.  This part's still under development, but it's already a whole lot more flexible and easier to use than the T3's scripting.
> It'll still support Dallas 1-wire for sensors, but it adds Modbus RTU over RS-485.  1-wire has never done well for long cable runs and doesn't tolerate noise very well, but RS-485 is reliable over thousands of feet and in noisy environments.  Modbus RTU has been around for decades and is supported by all sorts of sensors and I/O devices.  I've been testing with everything from < $10 quad relay boards from China to $400 intrinsically safe industrial I/O modules and assorted temperature, pressure, and humidity sensors.  The BASIC interpreter has access to Modbus and does floating point math so transforming sensor data is easy.
> I'm planning to add the ability to upload weather data to Weather Underground directly, but that's not done yet.  It'll also have a basic weather display in the web interface.
> It has only one external RS-232 port versus two on the T3, but it adds an internal GPS receiver with SMA antenna connector and includes a GPS antenna so most users won't need to connect any serial devices.  It has
> 32 MB of internal flash memory that can be used for local data logging, and a battery-backed real-time clock that can be automatically synced to the GPS time and/or NTP.
> Physically it's about 1/4" larger than the OT3m in all dimensions, with a flanged aluminum case that's easier to mount to a surface. I expect we'll have more compact versions to replace the T3-Mini and T3-Micro eventually but those are going to have to wait until late in the year.
> I'm waiting on another round of PCBs right now that will test out a different connector layout and if those work out they should be in production in a few weeks.  The introductory price is planned for around $140.
> I opted not to use Bluetooth because frankly Bluetooth has been a huge pain in other projects I've done, it's locked down on iOS, and when everything is working right it gets you the equivalent of a dumb serial connection.  The T4 supports WiFi Direct and can be used without other network infrastructure or while your phone is connected to another WiFi network (at least for most current phones), and while iOS doesn't support Direct (of course) it'll at least connect in legacy mode.
> I'll make sure that one way or another APRSdroid is able to connect over the WiFi link, and for desktop apps it'll support AGWPE's TCP API.
> The software has a high degree of commonality with the ADS-SR2 repeater and has some non-APRS related features that will probably stick around, like the ability to play WAV files over the radio port and send and receive DTMF tones, both of which are handy for scripting.  All of the
> SR2 software features that don't require two radio ports, including Echolink connectivity, *could* be implemented on the T4's hardware but I'm not going to promise all of those at the same price.  If there's sufficient interest I might make some extra features available as paid add-ons, so you don't have to pay for features you don't need and so I can keep paying the rent.
> If there's anything you'd particularly like to see in the first release, let me know!
> Thanks and 73,
> Scott
> N1VG
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