Spotter is the little screen that rides up front with you. After a fair amount of rework, the Drive screen is doing real work. One quick look tells you the trailer is awake, the battery is healthy, the tires are right, the sun is feeding you watts, and the wiring back to the trailer is doing what it should.
What Spotter is
Spotter rides in the tow vehicle. The truck, the SUV, the front of the motorhome, wherever the driver can see it. The trailer is in the mirror. You want to know about it without taking your eyes off the road for more than a glance.
So Spotter is a glance. Battery state. Tire pressure with a target. Solar input. Turn signals. Brake light. And a quiet bar across the bottom that lets you flip to lights, alarms, and setup when you are stopped.
That has always been the job. What changed this round is how well it does it.
What the Drive screen tells you
From the screenshot above, top to bottom:
- The header. Green dot means the trailer is connected. The label next to it says the trailer profile you set up, in this case a tandem axle. Out to the right are the turn signal arrows, the current speed, and a clock. The arrows light up amber when a turn signal is on, the same as the trailer lights behind you.
- Battery card. A big arc dial showing state of charge, with the actual voltage underneath and an estimate of how long the trailer can run on what is in the battery right now.
- Tire pressure card. Each tire shown in its own tile with a target pressure at the top. Numbers go amber if a tire drifts low. A flat is the one thing you really cannot miss on a tow.
- Solar card. Watts coming in right now, and how full the array is running compared to what it could do in full sun. Spotter does not know what your panels are doing, only what is showing up at the battery. That is enough. If solar drops to zero in the middle of a sunny tow and the battery percent starts heading down with it, you know something is wrong while you can still do something about it. Catch it on the road and the 12V fridge stays cold all the way in. Miss it and you arrive to spoiled food, or worse, a battery that gives up while you are still trying to level and hook up after sundown.
- The lamp strip. The bottom row mirrors the trailer's 7-pin wiring. Running lights, left turn, brake, right turn, and reverse. If the truck pedal is down, the brake circle lights red. If a bulb is out or a wire is broken, you see it before the highway patrol does.
- The tab bar. Drive, Lights, Alarms, Setup. One tap to each. Drive is the only screen meant to be looked at while moving. The other three are for the rest stop.
The new setup wizard
Earlier versions of Spotter wanted you to write the network name, password, and gateway address into a small text file on an SD card, then slot the card into the back of the device. If you got a character wrong you pulled the card, plugged it back into a computer, and started over. The new version walks you through it right on the screen. Pick a network from a list. Enter the password. Confirm the gateway. Done. Spotter remembers everything across power cycles, so next time you plug it in it just shows up.
Alarms while you drive
The other big chunk of this rework was the alarm path. Lots of small things can go wrong during a tow. A galley cabinet pops open at the first rough section of pavement. The fridge gets bumped off. A door latch did not catch. Spotter now listens for those events from the rest of the rig and raises an alarm right on the screen when one fires. Not every event needs to interrupt you. So which events are alarms is something you set yourself on the Alarms tab. The fridge running while you drive should not alarm. A bathroom light left on probably should. Spotter remembers your choices.
What is still to come
The basics are functioning. There is still real work ahead. The blind spot indicators on the sides of the Drive screen are wired in design but not yet to live sensors. The full-screen alarm overlay for the loud events, like a cabinet door swinging open at speed, is being polished. The lights and setup screens have layout work to finish. None of that should slow down putting Spotter on the dash of a vehicle and using it.
If you want to follow along or build your own, the code lives at github.com/trailcurrentoss/TrailCurrentSpotter. Like everything else in TrailCurrent, the hardware, the firmware, and the case files are open source and free to use.