Blynk and Nextion

Three backticks for and aft, not two :slight_smile:


dohhh sorry about that :confused: i shall rememebr that for future posts, cheer Gunner. Just to add, its when i uncomment //bt1.setValue(1); or //bt1.setValue(0); on my skimmer button BLYNK_WRITE(V2){ i get the compling issue.

As I don’t have NexHardware.h I just used an empty file and complied for Mega 2560 using IDE 1.8.7 on Win8.1 (also 1.8.8 on Win10) and the latest Blynk lib.
No errors with bt1.setValue(1); and bt1.setValue(0); uncommented in BLYNK_WRITE(V2). :+1:

strangly i just tried it with no errors to,very strange as i havnt chnaged anything. upoon tetsing, sometimes blynk misses the button pressed on the nextion and dosnt act and vice verser. how could i get round this? should i add flags

I think I’ve found something worth looking at: It’s the way the two DS18B20 are set (resolution) and how they are interrogated (blocking).

According to the datasheet ( table on page 3) it takes 750ms (!) (at 12 bit resolution) to get the temperature.

take_temp_readings() is called once per second (not sure if that is practically necessary). This is close to the time it takes to read the temperature from the sensors.

What I would change in the first place:

void take_temp_readings() 
  tanktemp = DS18B20.getTempCByIndex(0);
  sumptemp = DS18B20.getTempCByIndex(1);
void setup()
  DS18B20.setWaitForConversion(false); // make reading NON blocking
  DS18B20.requestTemperatures();       // start conversion for first reading 
  timer.setInterval(2000L, take_temp_readings);  // Setup a function to be called every 2 seconds

}//--(end setup )---

thank you for noticing that :slight_smile: i have made the changes and the code seems much sommer now :slight_smile: and is no longer missing a button press either from the nextion. thank you so much for your help. If theres anything else that catches your eye please shout :slight_smile:

Update, my idea with changing the button value works but if I change the page on the nextion and go back to the original page, all the settings are gone -.-

@Bundy FYI, as your issue’s posts got longer, I moved them all into your own topic.

I also have a 2.4" Nextion display, but has so far it is only used it as a Weather Display for Blynk Data and I have not integrated any touch functions back to Blynk, so this is interesting reading for when I finally get around to that.

Sweet cheers Gunner :slight_smile: ahh fair enough, I guess that data is refreshed at a set interval? I’m thinking this part may have something to do with it

// Page change event:
void page0PushCallback(void *ptr)  // If page 0 is loaded on the display, the following is going to execute:
 CurrentPage = 0;  // Set variable as 0 so from now on arduino knows page 0 is loaded on the display
}  // End of press event

Maybe set the button values again here although I’m not sure how to store a button value as a int instead of this uint32_t number5 = 0; where I could then use a statement like bt0.setValue(number5); so when the page is loaded so is the button value

@Bundy: Good to hear! :sunglasses:

No reason to shout :grin: Just one more thing worth looking at is the use of the timers as you use a number of them and many run functions in parallel. It does not seem to be an issue as the functions do not block.

But, anyhow it’s always a good idea to have a look at @Gunner’s collection C++ Blynk (Legacy) - Code Examples for Basic Tasks - #49 by Gunner - in this particular case I’d
recommend the topic “#12 - Timers simplified… perhaps…” → “Staggering Timers”

Sweet thank you I’ll take a look into that and make the required changes. Once iv added all my features, I’ll then go back through it all and add arrays and try to make things more compact and simplified.

Continuing on from my previous issue, I think iv found the solution.

This video shows how to store the button value within the nextion editor and then call up that variable when you change pages. Perfect! Keeps a bit of code off the arduino :smiley:

Next step is, display hour, minute and second in text boxes on the home screen

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Failing miserably at sending of the time to a txt box -.- I tried calling the hour by

String hour1 = String hour(); 

And then sending that as a String to the txt box but nothing happens :confused:

Not sure if I need to convert it to the buffer and then send it like I did with the temperature or what.

If anyone has any ideas or examples that may help me that would be great :slight_smile:

@Bundy: What I usually do to display date and time in the app is to put everyting (with leading zeros) into a string using sprintf([…],[…]). Should work in an equivalent way in your case.

void dateTimeDisplay()
  char currentTime[20];
  sprintf(currentTime,"%02u.%02u.%02u / %02u:%02u",day(),month(),year(),hour(),minute());
  Blynk.virtualWrite(V10, currentTime);  

Sorry I mean sending to the nextion, I have the time displayed on the blynk app at the moment. Another issue I have found with the buttons is that I can’t seem to change the variables I set for each button from the arduino. If I press a button on page 2, it turns a button on on page 1 like it’s suppose to for the nextion. But if I change the state or variable from the arduino it seems to ignore it. I must be setting the variable wrong.