Full duplex with HC12, on hardware port, with Nano.

Projects General Guidance
1

Hello,

I am working with Nanos, and HC12 boards.
Until now, I was using the softserial, but I realise that I need now the speed of the HW serial.

I am starting a new post since this one is quite old, but the idea is quite the same:
https://forum.arduino.cc/index.php?topic=471982.msg3229108#msg3229108

Would it be possible to have on a Nano, 2 HC12, one for TX only (a) connected on Serial TX, one for RX only(b) connected on Serial RX. unused pin would not be connected. (then only +5, gnd, and either TX or RX).
(a) and (b) will have different channels (set before, since the hc12 config is stored in a non volatile memory), but same rate (I would like to have at least 57600)...

Serial.read would read incoming from the (b), and Serial.write would send via (a)..

of course, to upload the sketch, I will add a switch on the +5v on HC12 boards to turn them off, and serial monitor won't work anymore. (debug and log are displayed on an oled screen via I2C)

But, would this be possible ?

thanks
JC

2

(deleted)

3

I didn't test yet...

Before changing all my boards and spend some time on this, I just would like to know if there are some known technical issues with this...

if a mega is really needed, I will switch, but I like the small size of the nano...

4

With one HC12 on TX right next to another on RX, you might find that the RX RF front end is swamped by the very close transmissions.

Do not expect the RF front ends of real cheap modules to be un-affected by very strong local RF fields.

A 434Mhz module can cause problems with a GPS (1575Mhz) if its close enough.

But as has been suggested what happened when you tried it ?

5

I see. ok. I will try today... :wink:
So any problem would be related with the 2 antenna, but not with the fact that 2 devices are managed with the single Serial port.

Thank you

6

Theres little point using 2 HC12 side by side, one for tx and one for rx as the RF link is half duplex, so can only send or receive but not both.
Using 2 , will simply cause the transmitting one to block the receiving one, as the radio in them has a broad band front end .
If you really need a full duplex RF link , then you will need 2 radios on totally differant frequencies, ie 433 and 900 Mhz, or an antenna diplexer which are expensive items.

7

jc999:
I see. ok. I will try today... :wink:
So any problem would be related with the 2 antenna

Its not just the antennas.

If some one is shouting loudly at you in one ear, can you hear a quiet conversation 100m away ?