simpleRTK2B + simpleRTK2BLite Hookup Questions

Q&A forumCategory: QuestionssimpleRTK2B + simpleRTK2BLite Hookup Questions
cjmssmd asked 7 months ago

Ardusimple support:  I received my simpleRTK2BLite – thank you for it!!

  • I have my simpleRTK2BLite inserted onto on the simpleRTK2B board (without the xBee board) as displayed here https://www.ardusimple.com/wp-content/uploads/2019/07/simpleRTK2Blite_hookup.png
  • Each is connected to a GPS antenna
  • simpleRTK2B is connected to Pixhawk4 and is working. It receives power and RTCM messages from the Pixhawk4 (which it receives from Mission Planner over an RF link..), and the “No RTK” light goes out, and Ardurover autopilot on the Pixhawk4 knows that the simpleRTK2B is in RTKFixed (or RTKFloat) mode.
  • I have not connected simpleRTK2BLite directly to the Pixhawk4 (yet – see my questions below).

Questions

  1. Achieving RTK on the simpleRTK2BLite. Will simpleRTK2B forward the RTCM messages that it is receiving on its Pixhawk connector to the simpleRTK2BLite?  If not, how should I get RTCM messages to the simpleRTK2BLite?  Must I connect the simpleRTK2BLite to the Pixhawk4 as another GPS?
  2. Receiving Heading information on my Pixhawk4. Will simpleRTK2B send a NMEA message with heading information?
  3. If so, what NMEA message? and, how do I configure the relative locations of the 2 GPS antennas so that it can calculate vehicle heading?
  4. If not, how do I get heading information on the Pixhawk4?  Must I connect the simpleRTK2BLite to the Pixhawk4 separately, and receive its NMEA messages on the Pixhawk4, and calculate heading on the Pixhawk4?

 
Thank you in advance! I am sure others are having these same questions.
Chris

Ardusimple Staff replied 7 months ago

1. If you bought the 2 items separately they are not pre-configured. We will soon publish the pre-configuration files for easy GPS heading. For connection to Pixhawk without using ArduSimple radios, you will have to send RTCM corrections from base station to the simpleRTK2Blite Pixhawk connector. The lite will send other corrections to the simpleRTK2B bottom board, and this one with output RTK position + heading in UBX format.
2. simpleRTK2B outputs heading in UBX format. Message ubx-nav-relposned. Heading in NMEA format will be provided by future version of the product.
3. –
4. GPS heading is not plug-and-play with Pixhawk, you will need to do the UBX-to-NMEA conversion.

cjmssmd replied 6 months ago

Hello Ardusimple support. One more followup question. In the configuration above (simpleRTK2Blite mounted on the simpleRTK2B board), I have RTCM corrections coming in to the simpleRTK2Blite’s Pixhawk connector. This is UART1, right? Above you say that the simpleRTK2Blite will “send other corrections to the simpleRTK2B bottom board”.. Does this mean that the top board (simpleRTK2Blite ) is using UART2 to talk to the bottom board? My understanding from the hookup page (https://www.ardusimple.com/simplertk2blite-hookup-guide/) is that the top board (simpleRTK2Blite)’s bottom XBee Header is also connected to its UART1. Correct? If so, what pins are used by the top board to send data to the bottom board?

Or, is it possible that the pixhawk connector on the top (simpleRTK2Blite) board is connected to UART1, and also is connected to the bottom XBee header??

Thank you

Ardusimple Staff replied 6 months ago

Hi cjmssmd,
Your understanding of the connection is correct. You can connect Pixhawk connector of simpleRTK2Blite to send RTCM corrections (you will use UART1 RX of simpleRTK2Blite), and it will use UART1 TX of simpleRTK2Blite to send corrections to the other unit.

cjmssmd replied 6 months ago

Hello Ardusimple support. Thanks for your answer. Would you mind taking a look at this diagram? My understanding is that on the top board (simpleRTK2BLite), I should receive RTCM messages on UART1 (RX). I shouldn’t connect the UART1 TX to the RPi. Then the top board uses its UART1 TX to send messages to the bottom board via the XBee headers (which are connected to UART2 on the bottom board).

https://docs.google.com/presentation/d/1q1jUD2uFssp0P0QlR4OD5LOUveWKF9IKPPJg_-xlasU

Ardusimple Staff replied 6 months ago

That’s correct!

cjmssmd replied 6 months ago

Thank You

1 Answers
cjmssmd answered 7 months ago

“If you bought the 2 items separately they are not pre-configured.”
–> OK, good to know. I was an early simpleRTK2B customer, and ordered the simpleRTK2Blite add-on to it. So I bought them separately (through no fault of my own…)
“you will have to send RTCM corrections from base station to the simpleRTK2Blite Pixhawk connector. The lite will send other corrections to the simpleRTK2B bottom board, and this one with output RTK position + heading in UBX format.”
–> Thanks.  I’ll send RTCM corrections to the simpleRTK2Blite Pixhawk connector.   On my rover I am receiving RTCM corrections on a Raspberry PI (via NTRIP); I can connect the RPi to the simpleRTK2Blite Pixhawk connector and inject RTCM corrections over that port.  
“simpleRTK2B outputs heading in UBX format. Message ubx-nav-relposned. Heading in NMEA format will be provided by future version of the product.”
–> Thanks for your answer.