Odd one for me, I normally do soil moisture and irrigation, but a client (a small town, cousin of a cousin situation) asked me to scope a parking pilot. 40 bays on two streets, in-ground magnetometer pucks. The ones on the shortlist are NC-200 style sensors that report car present / absent plus a battery level over LoRaWAN, EU868, class A, OTAA. Datasheet says an uplink on every state change and a heartbeat every 6 hours.
They already have a Hermetry org for their water network, so the platform is a given. I saw a “Hermetry City” sub-forum here and the product name in the menu of the website, so my first instinct was to use that and get parking out of the box. But I can’t find any setup page for it in the docs and our pilot has to run from March.
Questions:
- Does City do parking, and where is it set up?
- If it’s easier without it, has anyone run parking sensors on plain LoRaWAN + boards in Hermetry and is it any good?
- Any gotchas with these pucks? They are under asphalt, so the gateway placement already worries me.
Ha, small world, I’ve done street lighting for a town like that, on City. No idea if it does parking though, and I never found a doc page for it either.
Same here. City, Safe and Forge have no pages in the docs, so for my last lighting job I scoped everything from the parts that are documented: LoRaWAN, alarm rules, boards. Ask your account contact about City if the client wants the name on it, but don’t wait on that answer for a March pilot.
OK, fair enough for 1. So what are people building with the documented parts?
For the pucks: mount the gateway high and as close as you can, asphalt plus a car on top eats a lot of signal. We saw SF12 on half our in-ground sensors at first. Check the frames log for RSSI/SNR per sensor before you sign off any bay.
We did 60 bays for a shopping centre car park last year with plain LoRaWAN and it’s been fine. You don’t need anything special for a pilot. What we built:
Gateway is a Basics Station gateway on a lamp post (the old UDP packet forwarder is not supported, so check yours speaks Basics Station). Sensors added as OTAA devices. If you have 40 to do, pairing mode saves a lot of typing, but it needs a shared AppKey on the profile, which our puck vendor wouldn’t give us, so we added all 60 as OTAA devices by hand. Not fun, budget an afternoon.
The vendor only shipped a JavaScript decoder. Hermetry doesn’t run decoder scripts at all, codecs are JSON tables. Ours was a layout frame on FPort 2 and took 15 minutes:
{
"id": "t.bay-puck",
"title": "In-ground parking puck",
"vendor": "Example maker",
"fports": [2],
"kind": "layout",
"frames": [{ "fport": 2, "min_length": 3, "fields": [
{ "at": 0, "field": "occupied", "fmt": "u8" },
{ "at": 1, "field": "battery_mv", "fmt": "u16be" }
]}],
"tests": [{ "name": "car present", "fport": 2, "hex": "010E74", "expect": { "occupied": 1, "battery_mv": 3700 } }]
}Send occupied as 0/1, then charts can draw it. For the map we made each bay an asset with its coordinates under a “Main Street” site and placed the sensor under it, then a map card on Status under an asset. Free/occupied colour comes from the site status.
Last thing: a Device offline rule on the profile. With a 6 hour heartbeat, use Recent message with interval 21600 and factor 2, otherwise dead pucks hide for days.
Silly question maybe, but is 0/1 really better than “free”/”taken” as text? Text reads nicer on a table.
Text only shows as the latest value, it isn’t charted. With 0/1 you get occupancy per hour for free with the hourly average.
Right, that’s the plan then. I got the codec working against the vendor’s test frames, though my first try had the battery as little endian and showed 29,710 mV, so check that byte order. Pitched it to the client as “pilot on plain LoRaWAN and boards” and they were fine with it. Gateway goes on the roof of the building at the end of the street. Cheers Brian.
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