Solution via LORAWAN¶

The hydroponic system is inspired by Ortocity, a system that allows control and watering of the soil of a module culture. The main inspiration come from usage of LORA technology.

In the following are annotation and investigation of the technology used. In the end, the use of LORAWAN hasn’t been choose because WIFI.

Creation of a LORAWAN Gateway¶

Because the previous LORAWAN gateway used by Ortocity wasn’t available at the begining of the investigation, a LORAWAN Gateway was created to allow Ortocity to send data.

The material used

A Lopy 4 board

https://docs.pycom.io/datasheets/development/lopy4/

The expansion board 2.0

https://docs.pycom.io/datasheets/boards/expansion2/

a WIFI antena

Process

The code to be uploaded on the Lypo

On recent computer, driver shall be present and pymark shall detect lypo devices and state connected at beginning, otherwise instal driver, etc … of lopy material :

https://docs.pycom.io/gettingstarted/installation/

Follow the instruction which are pretty basics.

https://docs.pycom.io/tutorials/lora/lorawan-nano-gateway.html

The gateway needs to be registered on the thingnetwork(TTN). in that purpose :

we create a python script with the code suggested in “Gateway ID” chapter to be run once uploaded
retrieve the files main.py, config.py and nanogateway.py files from github, and just put local wifi ssid&password into config.py
just follow throught the instruction on registering your gateway (with gateway ID generated, and the correct frequency&portal from where you are)
Verify the good reference of the gateway on TTN platform

Note

The main issues come from uploading code into lypo.

You needs to upload last firmware on the device following the method: https://docs.pycom.io/gettingstarted/installation/firmwaretool.html

during firmware update erase flash on lypo

Interface with Lypo can be done with atom IDE with pymark module installed

Note

make sure the lopy works, with the following simple program : https://docs.pycom.io/gettingstarted/programming/first-project.html

update the firmware https://docs.pycom.io/gettingstarted/installation/firmwaretool.html

with atom and Pymark ad-on, upload lora-gate way code https://docs.pycom.io/tutorials/lora/lorawan-nano-gateway.html

useful video : https://www.youtube.com/watch?v=d7CHfmqkVWc

Create Lora device, node¶

Warning

This can be used to test the LORAWAN gateway when Ortocity isn’t available.

NOT USED IN HYDRO PROJECT

Material:

1 Lopy 1 from pycom

https://docs.pycom.io/datasheets/development/lopy.html

extension board v2

https://docs.pycom.io/datasheets/boards/expansion2.html

wifi antenna

Process:

follow the install instruction for ABP Node https://docs.pycom.io/tutorials/lora/lorawan-nano-gateway.html use the file node_ABP.py and the same config.py from github use also device EUI python script and run to have the Device EUI for device registration on TTN application create an application on TTN, for the application create a new device, use device ID you want and device EUI from python script save in node_ABP.py the info from the device created in TTN application. in device overview copy device adress into dev_addr copy Network Session Key into nwk_swkey copy App Session Key into app_swkey upload node_ABP.py(renamed into main.py) & config.py into lypo device (thought atom) in TTN application, in “data” tab verify that data arrives possible to need to reset Lypo with reset button close to Lypo LED & reset the frame counter from devices overview page

Informations that are transfered are only a counter for the moment, with the line : “s.send(pkt)”. We want to test the transfert the value of a potentiometer connected to a PIN of the Lypo. All changes from emetor persepectives happened in main.py

Resistor needs to define an input of the Lypo as variable input :

!!respect the pinout of extension board https://docs.pycom.io/.gitbook/assets/expansion2-pinout.pdf not all pinout can allow IN/OUT connection, for this exemple, didn’t found any clear documentation on the subject, got inspired by code from OrtoCity project call the measurement of the resistor “res_input()” Now it is needed to convert the value from an INT to a BYTE that is the only format to be transfered as data through LORA. import struct librairy for convert whatever variable into byte https://docs.python.org/3/library/struct.html a video to understand better struct https://www.google.com/search?q=struct+pack+tutorial&oq=struct.pack+tut&aqs=chrome.1.69i57j0l2.8730j0j7&sourceid=chrome&ie=UTF-8#kpvalbx=1 convert the measured resistence into a byte

val_send=struct.pack('i',val_res)

Send the byte in TTN application, you can add a payload format to display the numerical value of the resistance (instead of the hexa value)

function Decoder(bytes, port) {
  // Decode an uplink message from a buffer
  // (array) of bytes to an object of fields.
  var decoded = {};
  var resistance = (bytes[1]<<8)|bytes[0];

  // if (port === 1) decoded.led = bytes[0];

  return {
    resistance : resistance,
  }
}

!!the first byte sent are the first byte recieved, needs to take care of the order in the payload format

Now we’d like to have a NodRed interface to get value from TTN and display it

Install Nodejs install node-red install node-red dashboard run node red install the “node-red-contrib-ttn” package !!careful if the internet paserel on which your are connected allows that you can import ttn exemple configure ttn uplink node with ttn app name & device ID in the function node retrieve the resistance value pushed by ttn payload format “resistance : msg.payload_fields.resistance” display value of resistance with text node, with value “{{msg.resistance}}”

Handle IN/OUT on lopy

declare IN/OUT on the right pin

p1_out = Pin('P8', mode=Pin.OUT)    # g15 expansion board”

!!at beginning were aiming for pin G20, but seems not working controlling it is pretty easy with python

if (lev_in.value()==0):
        p1_out.value(1)
    else:
        p1_out.value(0)

here lev_in represent the water level sensor.

Next is to transfer order from Node Red interface to Lopy, a button to turn ON LED Info are transfered from TTN do device via downlink, now info are send as fields and not payloads

on device, nothing is recieved. when sending downlink with payload from TTN interface, we can see the payload is recieved

!! needs to understand the limit size and what informations can be send previously function from node-red was sending fields, which never managed to retrieved on device, and supposed to take bandwith

change the function to send raw payload

to pass switch value to a payload, just put it in serie with passing throught output parameter in switch node in function, pass switch value simply to raw payload

retrieve payload switch info in python from lypo

pass waterlevelswitch throught TTN to lypo, use function in payload formats from TTN

retrieve water level in node red function :

investigate DB with nodered