serial question

[Thomas Mabry]

I have a flarm view and l-nav in my glider with a tbeam. Both input/output RS232. If I only want the Input from the Lnav (for databridging to the oudie via bluetooth) and only want the output to be to the Flarmview can that be accomplished with one serial connection or do they need to be split up?

Also the flarmview has 2x rj12 connections on the back. Could the LNAV be plugged into one and the other conected to the tbeam (via ttl to rs232 converter), thus saving a serial for another use. 

Thanks!

Thomas

[Moshe Braner]

Hi Thomas.

A few things to keep in mind:

* The T-Beam outputs TTL level, you need a TTL-RS232 converter, as you mentioned

* SoftRF at this point only outputs serial data, does not accept any input (but see below)

* Moreover, the "RX" pin on the T-Beam CANNOT be used as an input, since it is connected to the USB port

* In general, one serial output can be sent to two inputs, in parallel, but not vice versa

* My SoftRF on the T-Beam can receive serial data for the purpose of sending it on to some other device, that's what is called "data bridging"

* Data to be bridged must arrive in the "secondary" serial port on the T-Beam

* The bridged data can be sent out via the main serial port, and/or wirelessly (Bluetooth or Wifi)

* For example, if the L-Nav sends vario data, it can be combined with traffic data originating in SoftRF into one data stream, and together they can be sent to the Oudie

In particular, to your question, if you use just the "secondary" serial port on the T-Beam, and set it as one destination for traffic data (the other destination can be Bluetooth), can route the output (from T-Beam) to the FlarmView that way.  And at the same time can route the vario data from the L-Nav into the input (to T-Beam) of the same (secondary) serial port.  So each of those connections are one-way, using just one wire (plus ground) - do not connect any input to two outputs.  Since both are on the same "port", SoftRF does not "know" that these are separate devices.  As far as it is concerned the secondary serial port is one device, and it won't data-bridge from an external device back into itself.  Which is fine in this case, I think, since you don't need to send the L-Nav data to the FlarmView nor vice versa.  For that configuration, you would not choose the main serial port as a data destination at all - you can only have two destinations, and in this case that would be Bluetooth and the secondary serial port.

Another approach is to choose the main serial port, connected to the FlarmView, as one destination (and Bluetooth as the other), while the secondary serial port, connected to the L-Nav, would only serve as an input for data to be bridged.  In that case the L-Nav data would also be bridged to the FlarmView, which (AFAIK) can't make any use of it, but hopefully would just ignore those sentences.

To use the secondary serial port (pins "VN" and "4"), set the "baudrate2" setting to something other than "0", e.g., "4" for 38400 baud.

[Thomas Mabry]

Thank you. That clears a lot up.

The biggest issue Im still having is that I want the information from the LNAV to be bridged  and sent via bluetooth (for the oudie to have vario and flarm data).

 So right now the plan is. Serial 2 RX (VN pin), connected to a ttl to rs232 converter that then connects to the LNAV, that handles the data in. Then splitting the output of serial 1 (TX pin) with one connection going to a BLE module (connection to the oudie) and the other going to another ttl to rs232 converter that goes to the flarmview. I had thought about just connecting a bluetooth module to the second port of the flarmview but the flarmview is 12v and the BLE module is 3.6-6V.

Wish I could figure out a way to include adsb as well but running out of connections to make that happen.

Thomas

[Moshe Braner]

Why do you plan to add a "BLE module" when the T-Beam itself is perfectly capable of sending out the data via BLE?  You can set up 2 destinations for NMEA output, one can be BLE and the other a serial port.  For the latter can use the "TX" pin, or can use the output pin (pin 4) of the secondary serial port since the L-Nav will only use the input pin, as you mentioned in your original posting.  An advantage of doing it that way is that the FlarmView will not receive all the non-NMEA output that shows up on the main serial port, and also not receive the NMEA sentences from the L-Van.  The data bridging will only send data from any input port to a different output port, in this case from the secondary serial port (L-Nav data) to the BLE destination (Oudie).

[Thomas Mabry]

okay, got it now. 

So LNAV---Rs232/TTL--VN (S2 input).          Pin 4 (S2 output)--TTL/rs232converter--flarmview

NMEA out: Bluetooth (5)

NMEA out 2: Secondary Serial (6)

Appreciate all the help, apologies for the confusion. I was somehow confusing the 2x NMEA Out and the 2x serials. Im just a simple pilot lol,  trying to slowly understand all of this and learn along the way. 

Thomas

[Bumpff Slam]

Can't help thinking that a diagram would help the conversation.  How about this..  

I guess you guys are talking about a Cambridge L-Nav  which needs GPS data from the T-Beam and I presume has vario info that is wanted on the Oudie.

Moshe already has an ADSB module option for the T-Beam.

[Moshe Braner]

Thanks, I didn't realize the L-Nav needed the GPS info.  The arrangement in your diagram should work, with the output from pin 4, after conversion to RS232 level, sent to both the L-Nav and the FlarmView.

Alas, you cannot add the GNS5892 ADS-B module to this setup, since it needs the secondary serial port, which is not available once this connection to the L-Nav is made.  Perhaps can use this alternative instead:

* Flarmview and L-Nav inputs connected to the *main* serial port output (pin "TX").

* The setting "altpin0" set to 1, to tell SoftRF to use the pin "VP" for input instead of "RX".

* The L-Nav output connected to the "VP" pin.

* GNS5892 connected to the secondary serial port (pins VN & 4).

Remember, you cannot send data into the T-Beam via the "RX" pin, since it is controlled by the USB interface.

[Thomas Mabry]

Lnav has built in GPS so no need to provide GPS information.