The JSN Modes 2 & 3 output serial data in Millimeters.
The frame format is: 0XFF + H_DATA + L_DATA + SUM.
After you see a 0XFF, the next (2) 8-bit values are the distance measurement, which are used to create the 16-bit measurement. The fourth value is the CheckSum (only the lower 8-bit of the Sum).
I have a Maxbotix and a JSN-SR04T V.2 unit built.
Both use Boron Sleep Mode and Solar.
I’m not happy with either just yet.
The Maxbotix MB7051 is very accurate and fits beautifully in a 3" PVC pipe as it’s enclosure. My thought is a short piece of PVC pipe wont draw as much attention for vandalism on the side of a bridge as a “typical” panel would.
The MB7051 is so accurate that I’m seeing the measured distance vary with Air Temperature on the hourly logs.
This can be up to a 3" swing just from the Air Density Change w/ Temperature over night.
The temperature compensation is easy, but adding an external temp sensor adds a little bit of complexity to a weatherproof enclosure (PVC pipe). It also needs a temperature sensor inside the enclosure to determine when to disable Li-Po charging (I normally use a TMP36 or 37).
I’m using a cheap 1-watt flexible solar panel that wraps around the 3" PVC Pipe enclosure
The JSN-SR04T V.2 performs better in Mode 2 verses the Default Mode 1 (for me anyway).
There are far less “bogus” values reported when using the Serial Output of the JSN.
But Serial Output requires soldering a resister to R27 which isn’t a lot of fun.
I’m powering the JSN from the 5V output of this Battery Shield, but this isn’t absolutely necessary.
I’m still not confident in the accuracy or precision of the JSN sensor, but it’s slowly gaining on me.
I’m leaning towards having the Boron remain awake in both Sensor Versions when the SOC is > 90%.
The benefit of using a variable Sleep (verses a TPL5110/1) is the Boron can be available for OTA flashes after it’s deployed in the wild.
Both Versions send distance, Li-Po Voltage, and SOC to ThingSpeak using a Webhook.
I’ll continue to tweak the Code and run the trials.
I’ll let ya know when I have something worth sharing for improvement ideas.