how can I use emlid rs2 as a base station

Q&A forumCategory: Questionshow can I use emlid rs2 as a base station
atwilcox asked 3 months ago
Hello everyone,
I have an emlid rs2 base station. It has a LORA radio built into it. For my rover, I have an ardusimple rtk2b (budget version).  I can configure it to receive rtk corrections (NTRIP messages blah blah blah) using u-center. This is not a problem. What I have no idea how to do is setup hardware to make the serial connection from the rover’s LORA radio to the actual rtk board.

Some options that I’d consider:
– I believe you typically would connect a radio via the power + xbee micro USB port like this TorxTecStuff guy did ( I can use an ftdi converter to get the radio that I have to talk to this port.
– connect the serial from the uart of the radio to the correct pins on the xbee socket. But I don’t know what the right ones are.
I’d appreciate any help… I’m working on a project in university and even just getting pointed in the right direction would be fantastic

Staff replied 3 months ago

You can use the Emlid LORA radio, and connect the JST connector from the radio to the JST connector of our board.
Then configure UART1 with the baudrate of the radio.
We would suggest disabling NMEA output on UART1 otherwise the radio will send this over the air.

This will be the easiest way.

replied 3 months ago

I actually can’t use the 6 pin jst connector for two reasons:

1) The pin header for the LoRa has 7 pins and I don’t have the kit to crimp and clip in a 6 pin connection with only the UART pins actually being used

2) The 6 pin jst is being used to connect ardusimple to pixhawk 6c

I tried more things last night…
Attempted to use the uart2 located on the xbee socket. Not sure what the issue is but it does not work. Tested the LoRa itself by connecting to TTL to USB converter and trying to get it to write to a tty on a laptop. This did not work either despite configuring the tty to use the serial comms settings laid out here:
(that is the data sheet for the chip that is in the LoRa)

So I’m leaning towards the problem being (at the very least) that the LoRa is not getting anything from the RTK base station. Of course, the serial port could still be configured incorrectly.

In u-center I setup 2-UART2 using PRT config in the configuration menu:

– protocol in : 5-RTCM3
– protocol out: none
– baud 9600 (radio default, from datasheet link I provided above)
– parity: none
– stopbits: 1
– bit order LSB 1st

other than that, I allowed some NMEA messages on UART2 and UBX config for 100ms period, 10 Hz frequency, nav rate =1, nav frequency=10

Any further advice?

replied 3 months ago

and is there a pinout for the xbee socket somewhere?

Staff replied 3 months ago

The xbee socket is labelled on the board, basically 1-VCC, 2-TX, 3-RX, 10-GND. Don’t forget to connect GND in addition to TX and RX, GND is needed for the connection to work.

A. Maybe we need one step back and first confirm that the radio communications work ok (maybe with other hardware that you used before, or using a loopback on the TX/RX of your radio and see if the Emlid received something back on the UART.

B. Once above is working, next step is to review your connections, maybe you can share some pictures of a diagram on how are you making such connections.

replied 3 months ago

The Radio module is using CMOS levels, should be usable on to the Arduino rails for UART2 as well (TX2 is the INPUT to the ZED-F9P), and powering IOREF with the appropriate level. There doesn’t need to be RS232 involved.

Make sure the radio module is actually getting data, use a terminal application check there’s actually data transiting the link.

Use something like RealTerm in HEX mode to see the actual bytes RTCM3 packets are primarily going to start with 0xD3,0x00 pair, or at least 0xD3.

The Base needs to be sending the appropriate RTCM3 messages.

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