question

admiral99 avatar image
admiral99 asked

Problems receiving serial data from MPPT 75/15 to ESP32/ESP8266

I'm trying to use a 'TTGO ESP32 Lora V2 1.6' via arduino to read the incoming serial data string from my MPPT and send the relevant values via the Things Network.


I've captured some data with my laptop from the MPPT and have written a similar program on another ESP8266 to emulate the output of the MPPT. The program I've written on the ESP32 seems to work, however when connecting it (with the correct JST connector) to the MPPT I receive no data in the ESP32's buffer.

I understand the MPPT has 5V output and as such I'm using a logic level converter in between. I've tested it with my Laptop and am receiving the data from the MPPT, also with the level converter in between.


I'm connecting ground and TX from the MPPT to ground and RX of the ESP. Also using the 5V connection from the MPPT to the 'high' side of the logic level converter, and the 3v connection of the low side to the LV connection of the level converter. When connecting with my laptop neither seems to be necessary: just ground + TX and Ground + RX on the laptop side seem to work.

Does the MPPT wait for anything specific before starting to send data? Is there anything like CTS / RTS involved?

VE.Direct
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

4 Answers
wkirby avatar image
wkirby answered ·

It just transmits once every second. There is no need to request anything. If it was working on your laptop, there is no reason the ESP shouldn't receive unless there is a communication problem between the MPPT and the ESP.
Have a look at the VE.Direct FAQ for more info.

https://www.victronenergy.com/live/vedirect_protocol:faq

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

admiral99 avatar image
admiral99 answered ·

I've changed my Arduino Sketch to use Serial1, soldered a new level converter to my cable and rechecked the wiring to the MPPT and it works! Finally I have data coming in, tested with both a 'TTGO Lora V1' and a 'TTGO Lora V2.1 1.6'.


Once I have the full MVP working I'll share it here. Goal is to gather input from the MPPT (V, VPV, PPV, I, H20, H21) once every 30 minutes and send these via lorawan ('The Things Network') to Cayenne to be graphed / displayed.

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

wkirby avatar image wkirby ♦♦ commented ·

Nice to hear it's working.
Please do keep us updated on the progress. The LoRaWAN work is interesting. Victron have a LoRaWAN module, but it'd be interesting to see your implementation of it.

0 Likes 0 ·
admiral99 avatar image
admiral99 answered ·

Initial test (running on a small lipo battery) seems to work well in parsing and sending the data.

Next steps are to include some temp sensors to monitor ambient and battery temperature and model & print a housing including a 24v->5v DC power supply.


victronboatmon1.jpg (50.7 KiB)
victronboatmon2.jpg (129.9 KiB)
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

rin67630 avatar image
rin67630 answered ·

You don't need a lever converter.
The pull-up from the MPPT VE port is so weak that it is easily clamped to 3.3V by the ESP input.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Related Resources

Additional resources still need to be added for this topic