Callback question

[vahithosan]

Hi. Thanks for sharing this library. I have a question. How can call function on esp32 with nextion button.

[brainelectronics]

Hi @vahithosan
What you need is the attachPop or attachPush callback function implemented in NexTouch.cpp

This requires calls of the nexLoop function of NexHardware.cpp.

Both functions are currently not implemented in this micropython lib. It would make sense to change to an async UART communication with the display and run this nexLoop call in its own async loop.

[vahithosan]

Thanks for your answer. I will also use uart with async. When the buttons are pressed, I send strings like print "page1" print "page2".

page1 = NexPage(nh, 1 ,0, "page1")
page2 = NexPage(nh, 2 ,0, "page2")
page3 = NexPage(nh, 3 ,0, "page3")

async def receiver():
    sreader = asyncio.StreamReader(uart)
    while True:
        res = await sreader.read(8)
        print('Recieved', res)
        if res==b'PAGE01':
            page1.show()
            p1n0=NexNumber(nh, 1, 8, "n0")
            p1n0.setValue(55)
        elif res==b'PAGE02':
            page2.show()
            p2n0=NexNumber(nh, 2, 8, "n0")
            p2n0.setValue(25)
        elif res==b'PAGE03':
            page3.show()
            p3n0=NexNumber(nh, 3, 8, "n0")
            p3n0.setValue(35)

I have one more question. Can we change the variable in a non-open page? For example, can we change the value on page 2 when page 1 is open? I couldn't change.(The variables are set global)

[brainelectronics]

I assume it would be more efficient to create the NexNumber objects outside of the while True: loop. With the code you posted, p1n0=NexNumber(nh, 1, 8, "n0") will be recreated everytime res==b'PAGE01'.

The actual root cause is the same name of your three NexNumber objects. All are named n0, which will update the NexNumber named n0 in your layout. This happens accross all your pages. May you have a look at the setValue function of common.py. This will require a change in the .HMI file and thereby the .tft file.

I don't have a setup here at the moment, but maybe you can try it like this.

page1 = NexPage(nh, 1, 0, "page1")  # NexHardware, page ID, component ID, name
page2 = NexPage(nh, 2, 0, "page2")
page3 = NexPage(nh, 3, 0, "page3")

# use a different unique name per NexNumber object
p1n0 = NexNumber(nh, 1, 8, "n1")    # NexHardware, page ID, component ID, unique name
p2n0 = NexNumber(nh, 2, 8, "n2")
p3n0 = NexNumber(nh, 3, 8, "n3")

async def receiver():
    sreader = asyncio.StreamReader(uart)
    while True:
        res = await sreader.read(8)
        print('Recieved', res)
        if res==b'PAGE01':
            page1.show()
            p1n0.setValue(55)
        elif res==b'PAGE02':
            page2.show()
            p2n0.setValue(25)
        elif res==b'PAGE03':
            page3.show()
            p3n0.setValue(35)

[vahithosan]

Thanks. I will try

[brainelectronics]

@vahithosan may you can provide the full code to run this simple example, like the complete main.py file? I would update the docs with it later

[vahithosan]

I have just started. That's all for now, but I'll post again when I'm done.
There are 12 pages in total. I will go back and forth between pages.

import uasyncio as asyncio
from machine import UART
import ujson
import time
from lib.nextion import NexNumber, NexHardware, NexText, NexPage

uart = UART(2, baudrate=9600, tx=21, rx=22)
uart.init(baudrate=9600, bits=8, parity=None, stop=1)

tx_pin = 21
rx_pin = 22
k=0
# # create Nextion hardware interface
nh = NexHardware(rx_pin=rx_pin, tx_pin=tx_pin)
nh.nexInit()

page1 = NexPage(nh, 1 ,0, "page1")
page2 = NexPage(nh, 2 ,0, "page2")
page3 = NexPage(nh, 3 ,0, "page3")
page4 = NexPage(nh, 4 ,0, "page4")
page5 = NexPage(nh, 5 ,0, "page5")
page6 = NexPage(nh, 6 ,0, "page6")
page7 = NexPage(nh, 7 ,0, "page7")
page8 = NexPage(nh, 8 ,0, "page8")
page9 = NexPage(nh, 9 ,0, "page9")
page10 = NexPage(nh, 10 ,0, "page10")
page11 = NexPage(nh, 11 ,0, "page11")
page12 = NexPage(nh, 12 ,0, "page12")

#Page1
p1n0=NexNumber(nh, 1, 8, "n0")
p1n1=NexNumber(nh, 1, 10, "n1")
p1n2=NexNumber(nh, 1, 12, "n2")
p1n3=NexNumber(nh, 1, 13, "n3")
p1n4=NexNumber(nh, 1, 13, "n4")
p1n5=NexNumber(nh, 1, 13, "n5")
#Page2
p2n6=NexNumber(nh, 2, 6, "n6")
#Page3
p3n7=NexNumber(nh, 3, 7, "n7")
#Page4
p4n8=NexNumber(nh, 4, 8, "n8")
#Page5
p5n9=NexNumber(nh, 5, 9, "n9")
#Page8
p8n10=NexNumber(nh, 8, 10, "n10")
#Page9
p9n11=NexNumber(nh, 9, 11, "n11")
#Page10
p10n12=NexNumber(nh, 10, 12, "n12")
#Page10
p11n13=NexNumber(nh, 11, 13, "n13")

async def receiver():
    sreader = asyncio.StreamReader(uart)
    while True:
        res = await sreader.read(8)
        print('Recieved', res)
        if res==b'PAGE01':
            page1.show()
            p1n0.setValue(55)

        elif res==b'PAGE02':
            page2.show()
            p2n6.setValue(25)

        elif res==b'PAGE03':
            page3.show()
            p3n7.setValue(35)

        elif res==b'PAGE04':
            page4.show()
            p4n8.setValue(45)

        elif res==b'PAGE05':
            page5.show()
            p5n9.setValue(1225)

loop = asyncio.get_event_loop()
loop.create_task(receiver())
loop.run_forever()

I don't use component id on buttons because password is one page. If the password matches, there will be a page transition.

Touch press event in Nextion

[vahithosan]

I simply tried.

import uasyncio as asyncio
from machine import UART
import ujson
import time
from lib.nextion import NexNumber, NexHardware, NexText, NexPage

uart = UART(2, baudrate=9600, tx=21, rx=22)
uart.init(baudrate=9600, bits=8, parity=None, stop=1)

tx_pin = 21
rx_pin = 22
k=0
# # create Nextion hardware interface
nh = NexHardware(rx_pin=rx_pin, tx_pin=tx_pin)
nh.nexInit()

page1 = NexPage(nh, 1 ,0, "page1")
page2 = NexPage(nh, 2 ,0, "page2")
page3 = NexPage(nh, 3 ,0, "page3")


#Page1
p1n0=NexNumber(nh, 1, 10, "n0")
p1n1=NexNumber(nh, 1, 11, "n1")
p1n2=NexNumber(nh, 1, 12, "n2")
p1n3=NexNumber(nh, 1, 13, "n3")
p1n4=NexNumber(nh, 1, 25, "n4")
p1n5=NexNumber(nh, 1, 26, "n5")
#Page2
p2n6=NexNumber(nh, 2, 8, "n6")
#Page3
p3n7=NexNumber(nh, 3, 8, "n7")

While on page 2, I tried to change the value on page 3, it did not change.

>>> page2.show()
True
>>> p3n7.setValue(35)
False

I was able to open and change page 3. Is this how Nextion displays work?

>>> page3.show()
True
>>> p3n7.setValue(35)
True

[vahithosan]

I was able to open and change page 3. Is this how Nextion displays work?

>>> page3.show()
True
>>> p3n7.setValue(35)
True

I was try like this yesterday

#Page3
p3n7=NexNumber(nh, 3, 8, "n7")

I wrote page name before object

#Page3
p3n7=NexNumber(nh, 3, 8, "page3.n7")

>>> page2.show()
True
>>> p3n7.setValue(35)
True
>>> page3.show()
True

Its working (variable change other page)

[brainelectronics]

@vahithosan thanks for the update! Sound great. I'll update the docs with your finding and code for callbacks.