How to connect ESP8266 Sensor Server to Pimatic?

---

How to use an ESP8266 Wifi sensor which acts as client sending requests to Pimatic server via API is pretty clear. In this case the sensor determines the update interval of a variable.
When changing the roles and let the sensor act as server the Pimatic server can control the request interval. For this scenario I didn’t find an example.

What is the best/easiest request/response format for the sensor (I am free in programming this) and with which device and how can I request the sensor server?

@Heizelmann
i know we have some @Developer doing nice things with esp chips.
maybe there’s one who can give some hints.

@leader21 The question is not ESP8266-specific. More generally the question is: How to bind a Pimatic device to a web-server-sensor

I’m not sure what you are trying to achieve?
I’m running a webserver on my ESP chip. Every interval it will update a value in pimatic over HTTP API. The ESP chip can receive commands over HTTP from pimatic to do some stuff (force update, reboot, turn off LED Matrix). All is done with simple GET commands. IS that what you are looking for ?

What I would like to have is a Pimatic device which updates some values by requesting a server. Requesting the ESP over HTTP like you do but getting a response with sensor values and with this update some variables.

Might be done with pimatic shell execute plugin and its devices like ShellSensor Device or ShellPresenceSensor Device. But you need an external script and some protocoll definition for the response to get it parsed. Too much for a non-developer.

If someone can support with a script would help.

May be for future it is a candidate for a feature request. Here my idea:

{
      "id": "myWebSensor",
      "name": "A web sensor",
      "class": "WebSensor",
      "protocoll": "json",
      "request": "192.168.1.100/requestall",
      "interval": 30000,
      "button": true,
      "debug": false,
      "attributes": [
        {
          "name": "temperature",
          "type": "float",
          "acronym": "T",
          "unit": "°C"
        },
        {
          "name": "humidity",
          "acronym": "H",
          "unit": "%"
        },
        {
          "name": "battery",
          "acronym": "Battery",
          "unit": "%"
        }
      ],
      "xAttributeOptions": [
        {
          "name": "temperature",
          "displaySparkline": false
        },
        {
          "name": "humidity",
          "displaySparkline": false
        },
        {
          "name": "battery",
          "displaySparkline": false
        }
      ]
}

The refresh button is optional and allows for requesting values on demand if interval is long for battery saving or set to infinite.

@Heizelmann If this is for battery-powered sensor I don’t think this is going to work unless you deal with a constant power drain. according to my findings ESP8266 won’t reachable in sleep-mode. If you have fat battery or your device is mains powered you can avoid the sleep mode, of course.

@mwittig You are right. It is a bad example. Forget the entries about battery in this example. And don’t be fixed to ESP. It might be any web server.

One of the commands my ESP responds to, is a force update of temperature. Pimatic connects over HTTP to the ESP to send the reuest. All the ESP does is triggering the function to push the information to the ppimatic API. Easier than letting pimatic talk to the ESP and receive a answer and then process that answer.

@koffienl: Can you give an example how to perform a GET request from ESP to pimatic in Arduino C-Code? I only found examples for PATCH request and tried it successfully but did not get working a GET request.

String get_data(String var)
{
  String rcv;
  String PimaticHostStored = HandleEeprom(pimhost_Address, "read");
  String PimaticPortStored = HandleEeprom(pimport_Address, "read");
  String PimaticUserStored = HandleEeprom(pimuser_Address, "read");
  String PimaticPassStored = HandleEeprom(pimpass_Address, "read");

  String yourdata;
  char uname[BASE64_LEN];
  String str = String(PimaticUserStored) + ":" + String(PimaticPassStored);
  str.toCharArray(uname, BASE64_LEN);
  memset(unameenc, 0, sizeof(unameenc));
  base64_encode(unameenc, uname, strlen(uname));


  const char* Hostchar = PimaticHostStored.c_str();
  const char* Portchar = PimaticPortStored.c_str();
  if (!client.connect(PimaticHostStored.c_str(), PimaticPortStored.toInt()))
  {
    Serial.println("connection failed");
    return rcv;
  }

  //yourdata = "{\"type\": \"value\", \"valueOrExpression\": \"" + data + "\"}";

  client.print("GET /api/variables/");
  client.print(var);
  client.print(" HTTP/1.1\r\n");
  client.print("Authorization: Basic ");
  client.print(unameenc);
  client.print("\r\n");
  client.print("Host: " + PimaticHostStored +"\r\n");
  client.print("Content-Type:application/json\r\n");
  //client.print("Content-Length: ");
  //client.print(yourdata.length());
  client.print("\r\n\r\n");
  //client.print(yourdata);
  const char* status = "true";

  delay(500);

  // Read all the lines of the reply from server and print them to Serial
  while (client.available()) {
    String line = client.readStringUntil('\r');
    if (line.indexOf("\"value\": ") > 0)
    {
      rcv += line;
    }
  }

  
  rcv.replace("\n", "|");
  rcv = getValue(rcv, '|', 6);
  rcv = rcv.substring(13, (rcv.length() - 1) );
  return rcv;
}

@Heizelmann Hi, If you want bi-directional communication with a simple protocol, look at MQTT (ISO/IEC Standard).

@koffienl
Thanks for the code snippet. But I try to use it for device control. When I enter the following in a web browser it works, but not with a a GET request from ESP

http:// PimaticHost/api/device/myesp01deviceid/changePresenceTo?presence=true

(found an example on https://forum.pimatic.org/topic/927/esp8266-as-doorsensor )

And this is my code which does not work.

  String url = "/api/device/" + deviceID + "/changePresenceTo?presence=" + value;
  client.print("GET " + url + " HTTP/1.1\r\n" +
               "Authorization: Basic " + unameenc + "\r\n" +
               "Host: " + PIMATIC_IP + "\r\n" +
               "Content-Type:application/json\r\n"
              );
  delay(500);
  while (client.available()) {
    String line = client.readStringUntil('\r');
    Serial.print(line);
  }

As far as I can see, there is no response.

Ah, now I see it. I forgot the client.print("\r\n\r\n"); I am not so familiar with HTTP protocol. Thanks a lot!

For all others this is working code:

  String url = "/api/device/" + deviceId+ "/changePresenceTo?presence=" + value; 
       //value is  "true" or "false"

  Serial.println("GET data to URL: " + url);
  client.print("GET " + url + " HTTP/1.1\r\n" +
               "Authorization: Basic " + unameenc + "\r\n" +
               "Host: " + PIMATIC_IP + "\r\n" +
               "Content-Type:application/json\r\n\r\n\r\n"
              );
  unsigned long timeout = millis();
  while (!client.available()) {
    if (millis() - timeout > 5000) {
      Serial.println(">>> Client Timeout !");
      client.stop();
      return;
    }
  }
  while (client.available()) {
    String line = client.readStringUntil('\r');
    Serial.print(line);
  }

Hi pimatic community,

I also use ESP8266 controllers which interact with pimatic on a Pi Zero.
There are different approaches I tried and still use in some device:

• Running a simple web server on the ESP, in my case to control an WS2801 LED strip. The strip can be controlled by any browser and I have pimatic button devices just opening an URL on the ESP server, e.g. via rule
  if button-rgbled-random pressed then execute "wget -qO- 192.168.178.46/rnd &> /dev/null"

• Another ESP uses deep sleep mode to check some sensors every few seconds with Wifi disabled to save power. If it detects a sensor value relevant to notify pimatic about it, it stores state information in the flash mem, reboots with Wifi enabled and then performs a GET request similar to the one referred to above. This works well for presence sensors for me and really saves power when the ESP only occasionally (e.g. 1-4 times a day) needs to notify pimatic about some interesting measurement. But I had problems setting String variables in pimatic using this way.

• Recently I played a bit with MQTT and so far I love it. It really works well in combination with ESPs and Mosquitto on the PI.
  For example I have a simple terminal box with an LCD 2004 and three buttons. The box is pretty stupid, it just connects to the pi MQTT server and subscribes to the topic “lcdbox/show”. I can use simple rules in pimatic to display time, date, weather, room temperatures, local tram schedules with real time offsets etc. To change the display’s functionality I don’t need to mess with ESP programming, I can just use anything on the PI and publish a message to the “lcdbox/show” topic. And the buttons just publish messages which trigger pimatic MQTT presence sensors. This allows me to also differentiate between short and long press on the buttons in pimatic rules.
  Currently MQTT is my favorite way of integrating ESP stuff with pimatic. As wutu already said, it is a standard worth looking at!

I am sure there are other promising ways to make it interact, but this is what I tries with success so far.