ESP8266 Community Forum

- Fri Nov 13, 2015 1:42 pm #33879 Hi everybody,

I´m just a beginner and it would be great if you can give your recommonadations regarding my projects i like to realise.

From my photovoltaic system i can read the actual production power by script. This production power i like to visualise by a little display near the washing mashine to decide if its a good situation to start a washing program.

I found this example in the web done by the MAX7219 display:
http://www.instructables.com/id/MAX7219 ... -for-ESP8/

But I also find similar projects which used an adruino in addition, wich I don´t wanna do.
Has anyone experience using only esp8266-(12) and MAX7219 to do somthing similar?
If yes please let me know and how you would realise this.

Out of the article I´m not so shure how to build the lua code. Isn´t it possible to use a generic max7219.lua and only send values to the lua module which should be displayed?

Thank you very much!

Best regards

- Fri Nov 13, 2015 4:19 pm #33903

Isn´t it possible to use a generic max7219.lua and only send values to the lua module which should be displayed?

Sure, that's possible. What would be your preferred way to provide the data to the the ESP? UART, MQTT, read the ADC ... you name it. It's more a question of how you intend to mesh up your overall system.

A simple and compact example for talking to the MAX7219 over SPI is given here: https://github.com/nodemcu/nodemcu-firm ... -149048951. Marcel described another use case with an 8x8 matrix at http://frightanic.com/iot/nodemcu-max72 ... x-display/

You could extend these by feeding values via the UART module: https://github.com/nodemcu/nodemcu-firm ... _en#uarton

- Sat Nov 14, 2015 4:53 am #33943 Thank you very much this gives me hope to keep on pushing and learning in this direction.

You are right the overall system structure is not clear yet and I have to think about and understand.

The data logger for my photovoltaic system can give me the values of actual power production by script:

Code: Select all#! /bin/sh
echo -e "GETPAR;2;0;Pges" | nc localhost 22222

The data logger itself i can and will not touch because it should keep on recording without disturbance.

Can I run this script/code directly on an ESP via Lua or do I have to use a raspberry in my network which will execute this script by cron or by call from the ESP in a php file?
Having "everything" inside of the ESP which controls the max7219 would be my favorite solution because of low complexity system structure.
Which do you think is the right solution for me to try to understand and realize?
Thank you very much.

- Sat Nov 14, 2015 7:40 am #33947 I do all the complex stuff on an RPi2 connected to my router. It talks to the ESP8266s using a very simple UDP protocol using a bare CSV datagram. The protocol is open but both ends are signed using a MD5 (actually the last 6 hex digits of the MD5 of the record + plus a shared secret) so that it is secure but not secret. This keeps the esp8266 end really simple to code -- and a lot easier that HTML over HTTP.

Please see my Developer FAQ for Q&A on nodeMCU Lua before asking a question here that's already been answered. This and the other official documentation should be your first reference for developing Lua Apps