Nobis Stove compatibility

[prunkdump]

Hello ! I would like to use your project with my Nobis Stove.

I'm pretty sure that it use a micronova controller board :

-> The WIFI module use the IOT Agua platform from Micronova
https://nobis.agua-iot.com/api-docs/

-> The connector is similar :

pin 1 : GND
pin 2 : SERIAL (3.3V)
pin 3 : 12V
pin 4 : 5V

But as you can see, I measure 3.3V on the serial line. So I'm afraid to put 5V on it.

Si I have put a single optocoupler to drive the SERIAL pin to ground using an USB to TTL device (only TX is connected)
I wait for the response using an logic analyzer.

I attached my schematic below.

But when I send :

0x00 0x01

I did not receive any response from the stove on the logic analyzer. I only see my messge. I use :

1200 baud 8bit 2 stop bits No parity No flow control

Did you see something I'm doing wrong ?
Have you 5V or 3.3V on the serial line when disconnected ?
Whats happen when you request a RAM register not used by the stove ? Does it always reply something ?

Thanks If you can help me.

Otherwise don't hesitate to close the issue.

Regards,

Baptiste.

[eni23]

@prunkdump

I have put a single optocoupler to drive the SERIAL pin to ground using an USB to TTL device (only TX is connected)
I wait for the response using an logic analyzer.
I attached my schematic below.

I am pretty sure that just one single opto won't be enough to fully create a working half-duplex uart driver. I never saw a schematic with just one opto, and even the one i'm using is kind of a hack, usually they consist of a diode and a transistor, something like this:

Have you 5V or 3.3V on the serial line when disconnected ?

Its 5V logic, but due to the half-duplex nature, its sitting at 5V when idling.

Whats happen when you request a RAM register not used by the stove ? Does it always reply something ?

Yes, it always answers, if nothing is at a location, its just 0x00

[prunkdump]

Thank you very much for your help.

I will try to use your schematic with 3 optocoupler and a 3.3V voltage regulator.

That's strange but my stove seems to use serial communication at 3.3v TTL level unlike the others Micronova boards. So I need to convert the 5V power of the stove to 3.3V to get the response through the RX optocoupler. It seems dangerous for the board to give 5V directly to the serial data line.

I keep you informed once I have done some experimentation.

Regards,

Baptiste.

[prunkdump]

Sadly the communication still doesn't works with the three optocouplers.

It seems that my stove use a special serial protocol or baud rate. Even if is was built by micronova.

Doing this I noticed a little error on your schematic. The ESP32 RX pin must be connected to the collector of the optocoupler and go to ground through the emitter.

Also sometimes you need to add a pull-up resistor on the RX line. In my case with an arduino AVR board, "Serial" don't enable a pull-up resistor by default on RX.

Thanks again for your help !

Baptiste.

[poupounetjoyeux]

Hello @prunkdump,

I'm in the same situation than you with my stove with a 3.3V on serial (Nobis stove) and have the same interrogation regarding the voltage I need to apply to be sure I will not burn the stove mainboard

Did you find a solution to make it work ?

Thanks by advance

[prunkdump]

Hello.

I managed to communicate with my Nobis stove but not with the serial port. I used the remote control wired connection port
and reverse engineered the protocol by capturing communication between the remote control and the stove.

Everything works fine but currently I have not written any code to communicate with the stove.

If you are interested by the schematic or the serial protocol contact me by email. You can find my address on my arduino-variometer project README.

But sadly, the protocol I found does not correspond to the one of this project.

Regards,

Baptiste.