GPS work great, but for some applications I need 2 outputs at the same time: 1 Bluetooth (BT) and the 2nd NMEA via RS2323 at 38,400 baud (to integrate sonar data with GPS).
Ports Menu in the manual states: " Note: The Data port does not output NMEA by default. The unit must be opened and the Serial NMEA Connection switch must be moved to ‘Ext Connector’. "
Schematic shows a DUAL_OUTPUT jumper. Maybe it isn’t closed by default. How do I close it? Solder? No pins for a physical jumper…
I get NMEA gibberish on a terminal with the switch flipped, but can’t get a “clean” output. I’ve checked and rechecked setting repeatedly. I do a fair bit with NMEA and RS232 streams so I don’t think I’m setting things incorrectly. Maybe it’s the serial to USB adapter, but it works with other devices.
Other observations:
Can only access configuration menus (no NMEA) via the ESP32 Port via USB (not via BT terminal connection).
NMEA sentences output on UBLOX port, but can’t access configuration menus.
Can anyone point me in the right direction? Thanks!
For the record I’m an environmental scientist that has set up all sorts of sensors, recording devices, etc., and have built some simple custom things. So, I know just a bit more than enough to be dangerous… My apologies in advance…
This is a new one on me, so I’m going to try this out first and make sure it works as expected. We like dangerously knowledgeable people at SparkFun, so you fit right in; no apologies required.
By the way, I really appreciate the detail and conciseness of your question!
I should get back to you this afternoon with a solution.
I was unsuccessful in getting NMEA messages on both Bluetooth and DATA port simultaneously, regardless of jumping DUAL_OUTPUT or changing other settings. I’ll poke the engineering team and see what we can do. Right now, I can get NMEA messages over either Bluetooth or DATA port (at b38400), but not both at the same time.
We have successfully gotten the NMEA messages outputting on Bluetooth and DATA port (38400) simultaneously. We haven’t really seen anyone use this feature in the wild, so it would be great to hear more about your application if you’d like to share.
Here are the steps I used to get this working:
Conductively bridge the two surface pads on the DUAL_OUTPUT jumper. Easiest way is just melt solder between the two pads. Luckily there are no sensitive components nearby, so it should be pretty straightforward. However, I DID mistake the plated through-holes labeled TX ZED RX nearby for the DUAL_OUTPUT jumper, which is why I ran into a roadblock last night.
Set the switches on the top of the board. The short version of this is set all switches away from the connector side of the board. We also recommend securing them in place (tape works well), as vibration could cause them to bounce around and make debug difficult. The long version:
a) “Connection” should be set to “Bluetooth” (Topside of board)
b) “Broadcast” should be set to “NMEA” (Topside of board)
c) “Data Port”, which should be set to “NMEA/Serial” (Underside of board)
Connect to the Surveyor via USB to the Config ESP32 port, and access the config menu via serial terminal (CH340 port, 115200 baud). Press “4” for Configure Ports, “2” for DATA port baud rate, 38400 “enter”, then press “x” twice to save the config and exit the menu.
Verify it worked. In my case, I programmed one of our ThingPlus C boards to grab serial output from pins 16 (RX) and 17 (TX), and pass them over USB serial back to my computer. Let me know if you’d like the code I used for this and I’ll send it to you. Most 3.3V microcontrollers with two or more hardware serial ports will work for this, or a dedicated device like a 3.3V FTDI Basic: https://www.sparkfun.com/products/13263
YellowDog is correct, RS232 can have voltage ranges from -15V to 15V, so you’ll an adapter of some kind. We do sell a MAX3232 based board, but you’ll have to evaluate whether it works for your project: https://www.sparkfun.com/products/11189
Let me know if this works out for you, and don’t hesitate to ask if you run into any roadblocks.
Think I’m well into or beyond my dangerous zone, but I’ll digest a bit and figure out what I do and do not understand. Glad to hear the jumpers are far from other sensitive components (I can solder connections, but I’m not all that deft…)
Have multiple devices that need to cooperate under different circumstances (GPS, sonar, video with GPS and sonar data text overlay) so a separate microcontroller may be difficult. Lions , tigers, and bears, oh my…
Thanks again for the the responsiveness. Thanks to Yellow Dog too!
Yup! It is confirmed. Honestly, the engineer who’d designed the board had forgotten that jumper was there, since it has been such a long time and no one’s ever asked us about it. The soldering should be pretty simple, even if you don’t have the best tools or experience. Just a little blob of solder between those two tiny square pads, then touch it with the iron until it sticks well and flows evenly across them, should take less than a minute all said and done.
Ah yes, the microcontroller I mentioned was onlyto verify that all is working as expected, a way to get serial output from the DATA port to your computer. I like to do that before trying to integrate more devices, just a quick sanity check, which is why I included that. It isn’t necessary for the sonar integration you described in your first post, just a nice intermediary step.
The thing you will definitely need is a way to get the TTL serial connection coming out of the DATA port converted to RS232 to feed into your sonar device. Attempting to hook them up directly would likely damage the Surveyor. Here is a resource for learning about the two communication methods: https://www.sparkfun.com/tutorials/215. Caveat is that the DATA port on the Surveyor is 3.3V, not 5V like in the tutorial. Please see our hookup guide for the pin definitions on the Surveyor: https://learn.sparkfun.com/tutorials/sp … e-overview
And please, let us know how it all works out, and if you need any more help from us! We love these crazy projects and want to support them as much as we can.
Thanks again! Think I know what I need to do. I’ll study up on the TTL vs RS232, 3.3 vs 5v, and pin info. Probably a month or so before I can tackle this in earnest, but knowing there’s a path forward is great.
Finally got back to this project. Worked just as described - perfect! Receiving BT to SW Maps and receiving NMEA via external port to a terminal. Now to try it with the sonar and etc.
Learned that after soldering the dual output jumper, keep the NMEA connection set on Bluetooth. If set to Ex Cntr I couldn’t get NTRIP corrections on SW Maps (even though I was getting BT data from the GPS). Not sure what that’s about, but doesn’t matter everything works great switched to BT.
Thanks again for the help! I’ll post again once sonar and camera feeds are up and running.
So everything works great until I make the NTRIP connection via SWMaps. Then communication with sonar breaks down. Clean output on the terminal. Can only guess that it’s because the GGA sentence is too long. Tried restricting the message length to strict (82 characters) via u-center, but that didn’t solve the problem (I think the sentence may get improperly truncated in that case). Will continue to explore… Any ideas in the meantime?
Watch the NMEA Talker ID, most legacy equipment expects $GP sentences, and can’t handle $GN, etc.
Via UBX-CFG-NMEA there’s options to limit the outputs to particular constellations, and set reporting pretending to be a 8, 12 or 16-Channel GPS receiver of 1990’s era.
Thanks clive1. I thought that might have been the problem and tried different settings to simplify the sentences and setup the “pretend” scenarios. Seems the sonar accepts all of the prefixes ($GP, $GN, or otherwise) and a lot more sentences in general that I expected it to, but something goes awry when the NTRIP is connected. Works perfect without the NTRIP connection.
I’ll retest that again though. Maybe I didn’t do it correctly post-NTRIP.
Also may try connecting the NTRIP directly through the GPS as opposed to via SW Maps. Maybe that will make a difference.
I have the same question but for an RTK Express device that was recently purchased. Does this answer apply to that device also? Did using both BT and RS232 eventually work? Thanks for any updates!
I did get BT & RS-232 to work by soldering the connection. Unfortunately, complications with the baud rate and NMEA sentence structure made it unworkable when NTRIP corrections were being received. May work for you depending upon what you are connected to the RS-232. I needed 38,400 baud and simpler sentences. There are settings to do so, but I couldn’t find the right combination even after going through all of the options systematically. I found a reasonable work-around for my needs. Also, simplifying the sentences impacted the BT stream too (limiting the data rate which was undesirable for my needs).
Note that I’m an environmental scientist with limited electronics skills so I may not have exhausted the possibilities. Best of luck!
Joe Klinger, PWS
Principal Environmental Scientist
ECOTONES, INC.
East Greenwich ~ Wakefield www.ecotonesinc.com
PO Box 1131, East Greenwich, RI 02818
401-256-5199 Phone 401-256-5191 Fax
Thank you for the update, Joe. I’m a marine geologist with an interested in seafloor morphology which has gotten me into acoustic mapping, especially using multibeam systems. I’m not too familiar with the electronics side, but I’m always looking for more and better navigation options! So far I haven’t tried to find the setup menu or open the device to see what’s inside. One thing I’ve done when NMEA messages aren’t precisely what I want is to feed those messages into the serial port of a laptop where a program picks out the pieces I want, reformats the message as needed, and sends that message out a serial port to the equipment.
Did you have to do anything regarding the TTL voltage levels?
Hi Roger,
Started out as a coastal geologist working on sediment transport and mapping sedimentary facies in the RI nearshore. Still do some of that work, but morphed into more of a biologist over the years…
One of my needs for the dual output was for side-scan sonar navigation.
Can you share what your using for the NMEA sentence corrections? That would work for when working from a boat.
@ rflood - In short, the Express is very capable of outputting NMEA over the DATA port while broadcasting over Bluetooth. The Surveyor uses slide switches on the internal board to direct serial traffic. The RTK Express has a much easier-to-use digital multiplexor to control what is output at the DATA port.
As Joe mentioned, we have a limited number of RS232 options to convert the 3.3V TTL serial to RS232. The board Joe linked to also looks great and may be a no-solder solution as well.
