SRTR - How do I get rain tags to work?

Sensors NFC & RFID
1

Kinda slamming my head against the wall at this point with these things. I picked up the SRTR a while back with 30 of the rain tags. I’ve just been running the basic example on an Adafruit Metro.

At first I tried just USB power and everything stock - never got a response even putting the tags directly on the antenna. No prob I figured, probably just need an antenna and more power. So I picked up this [MIKROE 4503 antenna and powered the Metro with 5VDC from the wall and set the transmit power to 27 dBm. Still absolutely nothing. I’ve tried multiple tags, angles, distances, etc… I’ve never gotten a single successful read.

Should it be this difficult? Is there any way I can troubleshoot this further?](MIKROE-4503 MikroElektronika | RF and Wireless | DigiKey)

2

a couple of questions:

Do you connect the SRTR directly on-top of the metro ? (pictures)

Which example do you use ? Any change to the default?

Is the UART switch set to SW-UART ?

Did you change the solder blob from on-board antenna to external ? (picture)

Do you get an error message while running the sketch?

In setup() before ‘setupNano(38400)’ add ‘nano.enableDebugging(Serial);’ and share the debug-data

Remarks:

Keep on 5 dbm. For the M6E the 5Vdc needs to be able to handle high/ constant current. A wall wart can normally not deliver that

Use the onboard antenna and put your tags right on-top-off the antenna.

3

paulvha:
a couple of questions:

Do you connect the SRTR directly on-top of the metro ? (pictures)

Which example do you use ? Any change to the default?

Is the UART switch set to SW-UART ?

Did you change the solder blob from on-board antenna to external ? (picture)

Do you get an error message while running the sketch?

In setup() before ‘setupNano(38400)’ add ‘nano.enableDebugging(Serial);’ and share the debug-data

Remarks:

Keep on 5 dbm. For the M6E the 5Vdc needs to be able to handle high/ constant current. A wall wart can normally not deliver that

Use the onboard antenna and put your tags right on-top-off the antenna.

Hi Paul,

I started doing some of your troubleshooting suggestions and after messing around with some more and I was able to finally get some tag reads but only at distances of up to barely 1mm from the perimeter of the antenna. I am using the first example that just continuously scans after a keystroke is entered. I added a couple lines to light up the onboard LED in the event of a successful scan. That way I can start the program over USB and then pull the cable so it switches to wall wart power (otherwise the board pulls from USB).

The tag pretty much needs to be sitting on the PCB just inside the silkscreened perimeter of the antenna. It’s been a while since my electromagnetics classes, but I should expect to get a nice flux in the middle of the circle, no? I’ve never gotten a successful read there.

I rigged up my multimeter to measure current from my wall wart which is rated for 5V 1A. At 27 dBm the total current draw is just shy of 900 mA which seems in line with the Sparkfun documentation on the SRTR. However, at any power I tried from 1dBm to 27, I get essentially no range at all. The discontinued sparkfun antenna claims a read range of about 1 inch and the one I have appears to be the same design - superficially, at least.

So at this point I guess the state of the problem is - we know the module is communicating fine, we know it’s spitting out high Tx power, but my read range is functionally zero when it should be ~1 inch.

4

Good to hear progress has been made.

For the antenna, did you remove the solder blob to the onboard antenna and add the solder blob to connect the external? (see https://learn.sparkfun.com/tutorials/si … al-antenna)

For the power supply. The SRTR is very sensitive to good power. A standard wall wart, although it can deliver 1A, normally does not have a strong capacitor. As the M6E works in bursts I noticed that mine works only well with LIPO connected directly to the SRTR external/battery power connection. A Lipo can provide a nearly constant power. Maybe give that a try.

As you set 27dBM the M6E will get hot very quickly. It will switch off, but once it cooled down normally it works again