Sharing NMEA

Q&A forumCategory: QuestionsSharing NMEA
Kaupoi asked 7 months ago

I’m planning to use SimpleRTK’s NMEA on 2 separate device same time. So I need to get NMEA to 2 diffenent USB (or 1 USB + 1 RS-232 9-pin) plugs. Do I need USB hub, or something else?

3 Answers
Ardusimple Staff answered 7 months ago

You can enable NMEA as output in USB (it is enabled by default) and in UART2.
If you bridge the TX and RX pins in UART2, you will have the NMEA string available also from the USB used by the XBee.
You can only do this if you are not using a radio mounted in the XBee header.

Kaupoi replied 7 months ago

I’m using lora xbee.
So usb hub won’t help?

Ardusimple Staff replied 7 months ago

As far as we know, USB splitters do not exist.
A USB hub allows you to connect several USB devices to a computer, but not a USB device to several computers.
You have another option, which is to set UART1 to output NMEA protocol and use a UART to USB adapter (you need to get one, but they are not expensive).

dskumher replied 7 months ago

Can I use Empty XBee USB of rover simple RTK2board to get RTCM correction stream from NTRIP client ? If yes, then Which TX/RX pins of UART2 to be connected to empty which XBee TX/RX pins so that XBee USB can be used as COM PORT for getting output of NTRIP client ?

Kaupoi replied 7 months ago

My other device that needs NMEA has RS232 db9-plug. So if I make a db9 plug to simple connecting: TX1 to db9 pin-2, RX1 to 3 and GND to 5, then use serial cable to connect to my device, it should work?

Ardusimple Staff replied 7 months ago

You will need a UART to RS232 adapter since the voltage levels are different, they have also popular prices 🙂

Kaupoi replied 7 months ago

So this should do the trick? https://www.artekit.eu/products/accessories/ak-rs232/

Ardusimple Staff replied 7 months ago

Yes, it should

Kaupoi answered 7 months ago

Don’t want to fry anything, so I’m asking, how do I wire AK-RS232-F  ( https://www.artekit.eu/resources/ak-rs232-f/doc/AK-RS232-F_Rev1.pdf ) to SimpleRTK Rover (with LR xbee radio)? RXD to RX1, TXD to TX1, GND to GND? Vcc, CTS, RTS?

Kaupoi replied 7 months ago

Any ideas?

Kaupoi answered 7 months ago

AK-RS232-F   –    SimpleRTK2B
GND               –    GND
TXD                –    TX1
RXD                –    RX1
Vcc                  –   3V3_OUT   –   IOREF
…without smoke. Now I have USB and RS232 supplying NMEA. I might need to order few more of these… 😉
Thank you.

Kaupoi replied 7 months ago

Vcc – 5V_OUT – IOREF works too. Should I use that?

clive1 replied 7 months ago

The ST3232 is capable of taking a range https://www.st.com/resource/en/datasheet/cd00002253.pdf
Using 5V_OUT won’t eat into the current budget of the 3V3 regulator.
While the uBlox part is tolerant of higher levels, I would lean toward using the 3V3 supply.

I will also note, if you need multiple NMEA RS232 feeds, you could just use the TX1 output, and fork it to multiple adapters.