power ESP32-POE-ISO over POE and use USB port for getting some data?

Started by u20p17, January 23, 2022, 10:18:45 am

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u20p17

Hi all,
I am looking for a microcontroller with POE function and USB Port. My plan is to power the ESP32 via POE and additionally connect it to my smartmeter via a FTDI FR232R USB TTL 5 V auf RJ11. Is the onboard USB just for flashing or can I also use it for my usecase?  If not, is there a USB header I can use with the ESP32-POE-ISO?

Thanks!

BR

LubOlimex

I don't think you can plug this FTDI FR232R USB TTL 5 V cable to the USB port of ESP32-POE-ISO. Furthermore I am not sure if software-wise it would be easy to use FTDI USB convertor with ESP32 chip.

But I am pretty sure you can connect your smartmeter to ESP32-POE-ISO directly without the FTDI cable. The software effort should be lower compared to using the adapter cable.
Technical support and documentation manager at Olimex

u20p17

Hi,
I think you are right. I want to run the follow python script on the ESP32: https://github.com/mweimerskirch/smarty_dsmr_proxy

As you can see I just need a serial communication to the smartmeter - and you can select the right serial port with the "--serial-input-port" argument.

The pin out of the P1 connector in my smartMeter is the following:
https://i.ibb.co/N9BhFcd/pinout-smart-meter.jpg

On which pins I would have to connect it on the ESP32?

EDIT1: Do you think it will work like this? https://i.ibb.co/smX8zJG/verdrahtung-ESP32-smart-Meter.jpg

5V isn't connected because the ESP32-POE should get the power over POE.

Thanks in advance!

BR

EDIT2: I already found a sketch for an mh et live esp32 minikit which is exactly doing at I want to do: https://github.com/weigu1/SmartyReader/tree/main/Arduino/SmartyReader_Ethernet/SmartyReader_Ethernet_v1_0

If I am right I would wire it like in the Edit1 and change in the sketch the ports/add ip config/mqtt config and that's it. So only question for now is if the wiring is ok...

LubOlimex

Why is 5V unconnected? How would you power the meter?

Also is the meter data signals working at 3.3V or only 5V? It would be much easier if the meter can work at 3.3V. Because the data signals of ESP32 are 3.3V. You might need level shifter on the RX line if it is 5V-only.

Also don't use that GPIO for RX. Use one of the free pins on EXT2. There is multiplexing in ESP32 and any pin can be set as RX by software means.
Technical support and documentation manager at Olimex

u20p17

Hi,
the 5V would be an power supply from the smartmeter to the ESP32. Here I found a demo project with a standard ESP32 (without poe) and he wrote, that the ESP32 with an Ethernet interface is on the limit for the power supply of the smartmeter. Thats the reason why I want to get the power for the ESP32 over POE and therefore I did not connect the power supply of the smartmeter.

Regarding the level shifter: yes, i will shift the 3.3V signal from the ESP32 to a 5V signal... Thanks for the hint.

So you would for example use GPIO 32 and 33 for RX /TX and set the multiplexing in the software? will this be done with SR_Serial.begin(115200,SERIAL_8N1, 32, 33); where 32 define RX and 33 define the TX ? If not how do you define which GPIO is used for RX/TX?

Thanks in advance!

BR

LubOlimex

Yes, GPIO32 and GPIO33 are free to use. Personally I would use the UART pins of the UEXT (they are also available on the headers), GPIO4 for RX and GPI36 for TX. The initialization of those would be similar to what you wrote:

Serial.begin (115200, SERIAL_8N1, 36, 4);
Technical support and documentation manager at Olimex