Quick project: Adding support for swimmingpool pump activation schedule [nodejs]

Hi everyone, here is a very quick post on the update I'm adding on my “NervSwimPool” project, which is a simple NodeJS project I built to get remote access to our swimmingpool devices (pump, robot, light, etc). I could explain this further to give a bit more context for this article, but, I feel lazy to do it, because I already lost some good time restoring my network access to the raspberry pi device hosting the program (stupid old/invalid network gateway setting of course).

⇒ So let's just get straight into the problem.

Main app entry point

Oaky, so looking into the NervSwimPool project repository, I now see that I have a main (single) src/index.ts file, ending with this content:

// add router in the Express app.
app.use("/", router);

// start the Express server
let server = app.listen(port, () => {
    console.log(`server started at http://localhost:${port}`);
});

process.on('SIGINT', _ => {
    console.log("process killed: releasing GPIO pins.")
    for (var i = 0; i<pins.length;i++) {
        pins[i].writeSync(Gpio.HIGH);
        pins[i].unexport();
    }
    console.log("Done releasing GPIO pins.")
    server.close(function () {
        console.log('Closed server.');
    });
});

So we start a server at that location, all good. But what I need now is to also periodically read a config file, and then check if I should activate the pool pump at the current time or not.

Side Note: just found this page on the building of a REST API in python: if I had to redo this project again that's how I would do it I think.

⇒ To handle this automatic schedule I added the following section in the swimpool.json file:

  "pump_schedule": [
    { "start": "10:00", "end": "12:00" },
    { "start": "00:00", "end": "03:00" }
  ]

And then I added a function to handle those schedule entries:

function process_pump_schedule() {
  // Should read the contend of our config file:
  console.log("Processing pump schedule...");
  let cfg = getConfig();

  let ranges: any = cfg["pump_schedule"];

  // Get the current time:
  const cur_date = new Date();
  const cur_hour = cur_date.getHours();
  const cur_min = cur_date.getMinutes();
  const cur_ts = cur_hour * 60 + cur_min;

  let pinIdx: number = pinMap["pool_pump"];

  for (let range of ranges) {
    // Check if we just crossed the "start" time:
    let parts = range["start"].split(":");
    let start_ts = parts[0] * 60 + parts[1];

    if (cur_ts > start_ts && cur_ts - 60 < start_ts) {
      // Should start the pump here:
      console.log("Enabling pump at " + range["start"]);
      pins[pinIdx].writeSync(Gpio.LOW);
    }

    parts = range["end"].split(":");
    let end_ts = parts[0] * 60 + parts[1];

    if (cur_ts > end_ts && cur_ts - 60 < end_ts) {
      // Should stop the pump here:
      console.log("Disabling pump at " + range["end"]);
      pins[pinIdx].writeSync(Gpio.HIGH);
    }
  }
}

Finally, calling this function every minute:

var interval_id = setInterval(process_pump_schedule, 60000);

⇒ Let's now restart the server:
- First I kill the existing node process:
```
$ ps aux | grep node
```
- Then I run the process manually with:
```
$ sudo /home/ubuntu/swimmingpool/scripts/start_pool_server.sh
```

But the timezone on that system is not correct:

ubuntu@ubuntu:~$ date
Sat May 14 11:45:14 UTC 2022
ubuntu@ubuntu:~$ timedatectl
               Local time: Sat 2022-05-14 11:45:46 UTC
           Universal time: Sat 2022-05-14 11:45:46 UTC
                 RTC time: n/a
                Time zone: Etc/UTC (UTC, +0000)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no

I found this page on how to set the timezone on ubuntu: https://linuxize.com/post/how-to-set-or-change-timezone-on-ubuntu-20-04/

So now setting the correct timezone:

$ timedatectl list-timezones
$ timedatectl set-timezone Europe/Paris

OK, now we are good:

ubuntu@ubuntu:~$ timedatectl
               Local time: Sat 2022-05-14 13:49:13 CEST
           Universal time: Sat 2022-05-14 11:49:13 UTC
                 RTC time: n/a
                Time zone: Europe/Paris (CEST, +0200)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no
ubuntu@ubuntu:~$ date
Sat May 14 13:49:52 CEST 2022

After some additional tweaking, here is the final version of the process_pump_schedule function I got:

function process_pump_schedule() {
  // Should read the contend of our config file:
  let cfg = getConfig();

  let ranges: any = cfg["pump_schedule"];

  // Get the current time:
  const cur_date = new Date();
  const cur_hour = cur_date.getHours();
  const cur_min = cur_date.getMinutes();
  const cur_ts = cur_hour * 60 + cur_min;

  // console.log("Processing pump schedule at " + cur_hour + ":" + cur_min);
  // console.log("Current timestamp: " + cur_ts);

  let pinIdx: number = pinMap["pool_pump"];

  for (let range of ranges) {
    // Check if we just crossed the "start" time:
    let parts = range["start"].split(":");
    // console.log("parts: " + JSON.stringify(parts));
    let start_ts = Number(parts[0]) * 60 + Number(parts[1]);
    // console.log("Checking start timestamp: " + start_ts);

    if (
      cur_ts >= start_ts &&
      cur_ts - 2 < start_ts &&
      pins[pinIdx].readSync() == Gpio.HIGH
    ) {
      // Should start the pump here:
      console.log(cur_date.toLocaleString() + ": Enabling pool pump.");
      pins[pinIdx].writeSync(Gpio.LOW);
    }

    parts = range["end"].split(":");
    // console.log("parts: " + JSON.stringify(parts));
    let end_ts = Number(parts[0]) * 60 + Number(parts[1]);
    // console.log("Checking end timestamp: " + end_ts);

    if (
      cur_ts >= end_ts &&
      cur_ts - 2 < end_ts &&
      pins[pinIdx].readSync() == Gpio.LOW
    ) {
      // Should stop the pump here:
      console.log(cur_date.toLocaleString() + ": Disabling pool pump.");
      pins[pinIdx].writeSync(Gpio.HIGH);
    }
  }
}

While I'm at it, I think I should also add support to automatically disable to pool robot after some time of cleaning (like 2hours maybe): Let's add support for that.

To achieve this I updated the /handle endpoint as follow:

var robot_timeout: any = null;

function stop_robot() {
  let pinIdx: number = pinMap["pool_robot"];
  if (pins[pinIdx].readSync() == Gpio.LOW) {
    const cur_date = new Date();
    console.log(
      cur_date.toLocaleString() + ": Automatic stop of robot cleaning session."
    );
  }
}

router.post("/handle", (request, response) => {
  //code to perform particular action.
  // We start with reading our configuration file first here:
  let cfg = getConfig();

  let auth = request.body.auth;
  let user = getAuthenticatedUser(auth, cfg);

  if (user == null) {
    console.log(`Cannot authenticate user with auth: ${auth}`);
    response.json({ status: "Error", message: "Cannot authenticate user." });
    return;
  }

  //To access POST variable use req.body()methods.
  // console.log("Received body: ");
  // console.log(request.body);
  // response.json({ result: 'OK', name: request.body.username });
  let act: string = request.body.action;
  let tgt: string = request.body.target;
  // Inverted pin values below:
  let relayVal = act == "enable" ? Gpio.LOW : Gpio.HIGH;
  let pinIdx: number = pinMap[tgt];
  console.log(`Setting pin ${pinIdx} to ${relayVal}`);
  pins[pinIdx].writeSync(relayVal);

  if (tgt == "pool_robot") {
    // We are activating/deasctivating the robot, so we should cancel the timeout if any:
    if (robot_timeout != null) {
      // console.log("Cancelling pool robot timeout callback.");
      clearTimeout(robot_timeout);
      robot_timeout = null;
    }

    // If we jsut enabled the robot, start the timeout:
    if (act == "enable") {
      // Duration below given in minutes:
      let dur = cfg["robot_cleaning_duration"] * 60 * 1000;
      robot_timeout = setTimeout(stop_robot, dur);
    }
  }

  // Send the state:
  sendStatus(cfg, response);
});

And of course I added the required entry in the config file:
```
  "robot_cleaning_duration": 120,
```

⇒ And this is it for this time, now I just need to monitor the pool and the log file for a few days
But right now, what I desperately need is a short nap lol. I can't keep my eyes opened anymore 😁

Quick project: Adding support for swimmingpool pump activation schedule [nodejs]

Main app entry point

Adding support for schedule handling

Fixing the timezone

Updated pump schedule function

Auto-disable pool robot

Conclusion