WOW! She works!!
The answer was incredibly simple and I’m almost embarrassed to say it’s obvious but some of this is new to me and my experience with Serial to date has been spotty. Here’s what I did…
I connected VCC and Ground on the Boron to the VCC and Ground on the sensor. I setup both sensors (A02YYUW & JSN-SR04T) to work in what is called ‘Mode 1’ so that every 200ms & 300ms respectively they send out the distance measurement over serial; no need to trigger the reading. So I connected TX (transmit) from the sensor to RX (receive) on the Boron and then simply used Serial1 to get the value in cm. Serial1 is mapped to RX and TX on the Boron and the good folks at Particle have made the setup so easy it confused me originally - it’s so simple!
Both sensors seem to work well. I have an accurate sonar device to calibrate them and their accuracy is within useable range at least in principle - I’ll let you know how it works in real life… LOL.
Thanks to all who helped out – I am really grateful to those who contributed as the solution was a combination of everything they suggested!
CHEERS