Hi,
I was given some Heltec V3 units as presents. They can be programmed by Arduino. I'm no programmer, especially Arduino.
I wondered what would be a useful use for them. They are low powered (UK 25mW) and consume little power.
I thought that they could be useful in an emergency, like a lost person or similar.
Using AI, I have got
1x as TX reading GPS.
1x as repeater. This could be place high, or even on a balloon, or drone.
1x as RX, which shows coordinates, time, date and count number on it's screen.
I'll be testing the range soon, and will let you know.
(Also on ETO)
Cheers, C.

 

Hi,
As there are no replies, I assume that no one's interested?

Anyway, I (AI) modified the 3x programs BASE-REPEATER and REMOTE, so that GPS is toggled backwards and forwards between them, so each end sends it's own GPS data. This would allow me to verify that messages are getting to both ends.
I used 4x frequencies, so that crosstalk between BASE and REMOTE can't happen.
(Also on AAC)
(P.S. I found out that GPS is only the American GPS, so as I'm not an American I should call it GNSS, but I won't )
C

 

How would the Tx know it's GPS location? Unless you add a GPS module to it.

 

How would the Tx know it's GPS location? Unless you add a GPS module to it.

Hi M,
Each has it's own gps, and they each send their position, then read the others position in turn.
C

 

So what is it we aint interested?
The project seems interesting, but there is no "hook" for a discussion. If you test the solution and share the results/problems faced there might be something to talk about.

 

So what is it we aint interested?
The project seems interesting, but there is no "hook" for a discussion. If you test the solution and share the results/problems faced there might be something to talk about.

Hi M,
At the moment I'm testing the range, using a REPEATER.
Once tested I will try different projects, i,e, Emergency search and rescue-Triggering a camera-Security-Remote control, and whatever my imagination comes up with.
C

 

In my opinion in parallel you should think about logging the movement, it could be interesting to mount it on an alley cat or stray dog to do some research

 

In my opinion in parallel you should think about logging the movement, it could be interesting to mount it on an alley cat or stray dog to do some research

Hi M,
This is a good idea, however these modules are low power and my tests would usually need a repeater, to assist mostly line of sight, and folliage. Do you know how to do it?
I'll look into it.
C

 

Hi,
It's mostly working, but seems to need better synchronisation. Any ideas?
C

 

Synchronisation , as in, the data is late?

 

Synchronisation , as in, the data is late?

Hi M,
No, I meant that the 2x modules need to talk in turn, or things get mixed up, I think I've fixed that now.
C

 

Hi, (Testing with no REPEATER)

I've had BASE and REMOTE kind of synching , with each other reading GPS and Txing while showing GPS on screen, then showing RX on screen.

If they both start at the same time, then they won't be RXing as their TXing, which also has to take into consideration, loss of GPS or loss of RX, then re synching.

They need to toggle like passing a Baton between them. (I did try this)

Any ideas please?
(Also on ETO)
C.

 

I would say you need some kind of handshake, first a module should ask "are you ready to receive" , if the answer is YES send the data, if the answer is NO (or should I say - no answer) store the data in buffer and ask again after 3 seconds. When NO becomes YES send the entire buffer of data and wait for feedback. If feedback is received clear the buffer.

On the other hand the receiver, while idle, upon "are you ready to receive" message should ignore all other messages until data buffer is received. If the buffer isnt received in 5 seconds, become idle again. You can also make a priority list, if one device sends data 3 times in a row, ignore next 3 sends (data would be kept in buffer) until the other device makes a send.

 

I would say you need some kind of handshake, first a module should ask "are you ready to receive" , if the answer is YES send the data, if the answer is NO (or should I say - no answer) store the data in buffer and ask again after 3 seconds. When NO becomes YES send the entire buffer of data and wait for feedback. If feedback is received clear the buffer.

On the other hand the receiver, while idle, upon "are you ready to receive" message should ignore all other messages until data buffer is received. If the buffer isnt received in 5 seconds, become idle again. You can also make a priority list, if one device sends data 3 times in a row, ignore next 3 sends (data would be kept in buffer) until the other device makes a send.

Hi M,
Note: For clarity, I use BASE and REMOTE, as both are TX and RX.

I've tried various versions similar to what you say.

Both modules read their GPS NMEA sentence string, then parse it and show it on their screen, while TXing this data, and RXing the others GPS data, then show that on their screen.
I've been showing each data on the screen for 15 seconds each.
Note, that the GPS and opposite data signals could be lost.
C

 

Hi,
They are now reliably talking. Next I'll try to range tests, then add the repeater.
C.