Nextion and Bascom

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Using the Nextion display with Bascom.

The displays handle all the graphics:
It is all stored in the flash on the display you design it on your PC
upload photos and graphics to the editor to be used on your display
upload to the display is done via RS232 or simpler by micro SD card
It handles the touch events for you

Communication to the avr is serial RS232

There is a limited instruction set that can be used to get the display to do some work
but its not well documented.

The first thing to do is to give the items on the screen useful names
because when you change pages the default ones get re-used
as an example the first touch button on a page gets named bt1
so every page you make will have a bt1 making it difficult to work out which page sent it

It can do a pop up page over the present one
it comes with examples of keyboards one is a number pad which pops up enabling numbers to be input.
It has a user password function.

The enhanced versions have more ram , flash , a RTC , general purpose IOs which can do PWM and faster cpu.
I have the enhanced version.

The size of buttons on the screen will need to be determined on the screen
for users to be able to work with big enough for a finger or stylus

This covers some of their functions more will follow as I learn them.

next post I will show a animated screen with the nextion code that does it

Regards Paul

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Now here is the animation

Slider tool

https://youtu.be/tSEj0gExWAI

h0 , h1 , h2 , h3 are the sliders
va0 , va1 , va2 , va3 are local variables to the page
Note variables can be made global available to all pages
the code runs in a timer which forms a loop
the first 4 lines are setting the slider to the variable value
each slider can have a value from zero to 100
as we go through the loop we add 10 to the variable
the if statement tests if it is greater than 100
if it is then it is set to 1

The code that runs the slider is

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Now full animation with picture box added

https://youtu.be/irECmmy1-ds

Picture box code animation
Pictures are loaded into the editor and are assigned a number automatically in the order loaded
they can however be moved up and down in the order manually
the animation is done by using a timer loop to load images in succession
the same way an animated GIF works
p2 is picture 2 box and pictures 62 to 66 are loaded one after the other
as we go through the timer loop
the if statement takes us back to image 62 (the first of the series)
when we come to the last in the series
this all shows as the yellow dots moving through the circle
with four picture boxes

Regards Paul

Duval JP · Joined: 22 Jun 2004 Posts: 1161 Location: France

hi Paul,
A new set of tools for nextion :https://www.mcselec.com/index2.php?option=com_forum&Itemid=59&page=viewtopic&t=14537
JP Wink

Duval JP · Joined: 22 Jun 2004 Posts: 1161 Location: France

hi Paul or other Nextion user,

I need your feedback on the 7" capacitive nextion screens.
do you use them?
I use the 5" resistive is good but by dint of tapping on the screen, it seems less reactive . before ordering (100€) I would like your opinion.
Is is working as the resistifs ?

I notice a bug ? : I have to display 30 text fields, the last one was never write. I had too add a "waitms xx" between fields. now is is working well maybe my buffer was too small too.
JP

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Hello JP
I have the 7 inch enhanced.
Have had no problems so far but have not had time to really use it
spent time getting the object colours and background colour so they are easy to see
yet to get working with bascom but sending from terminal on PC to test.
The intelligent series would be nice for a commercial project
it can play video files which would be good for help instructions.

I measured the current yesterday it draws 350ma.

I was busy with making a battery cabinet for my NiFe before Xmas
then at my home here on NSW south coast smoke and ash was the problem
luckily fires were not a direct threat.

Regards Paul

Duval JP · Joined: 22 Jun 2004 Posts: 1161 Location: France

hello Paul
Indeed we followed the terrible fires that ravaged Australia and I had a thought for my friend whom I have never seen.
Today in France we have a very strong winter storm. A weather to work at home. Hoping the mains is not cut off.
Thanks for your message, I ordered the display.
I'll pass on my experience with it.

JP Wink

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Hello JP
The important thing I have found with the display is not to get too small
if your going to use it with finger and not a stylus.
Nextion Global variables & objects are needed when you want
a screen to stay the way it is when changing to another screen
so when you return its not back to default
so like bascom local variables and normal global variables.

The number object only accepts digits no decimal point.

The float object also only accepts digits and you have to set up the position of the decimal point
so if you have 12.34 you send it 1234 then set attributes ws0 and ws1
ws0 is number of digits to left of decimal point
ws1 is number of digits to right of decimal point

so we set them both to 2 and get 12.34 but if we send it 123 we get 01.23

This requires some code in bascom to work out what to send as we need to remove decimal points from numbers
I find it simpler to convert to string and use text box object on the nextion as the decimal point is inserted by bascom.

So what use are the number and float objects?
They will allow you to use the nextion code to manipulate numbers.

A note on the fires here :
We have had storms here too dumping 40 to over 200 mm of rain in places
this has put out one of the fires and suppressed others
put water into our dams
but has also caused local flooding and ash run off into the dams

Regards Paul

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Now some bascom driving nextion
The avr sends QPIGS with CRC to my inverter it sends back its present status
This is what comes back
(243.4 50.0 230.3 50.0 0437 0432 010 404 50.50 000 083 0035 00 09 079.8 50.63 00000 00110110 00 00 00455 010†

243.4 is grid volts ,50.0 grid frequency , 230.3 inverter output volts, 50.0 frequency
So it can be seen that a space is the delimiter
Also there is a CRC at the end with CRLF
The split command chops it up into its parts each work() variable contains a value
I send each value to the nextion text box to be displayed
I use the covx command on the nextion to convert text box to number
I use the if command on nextion to control animation
For example if the grid voltage is too low the grid display flashes red/green
va13.val is a number variable
this runs in a timer of 500ms
Note use of ==

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

I have a problem with the Nextion wave form component.
It does not remember the data when you change pages.
So I need a buffer that I can push bytes into at one end and they move along the buffer
when its full the bytes keep moving along with the byte at the other end dropping off (lost)
updating the values while not displaying on the nextion.
I can then send the buffer to the display.
I would like some help to create this
This would benefit anyone using the nextion.

Being able to creat 4 buffers is needed as the component can display 4.

Regards Paul

Duval JP · Joined: 22 Jun 2004 Posts: 1161 Location: France

you want to create FIFO algorithms
there are many examples on the web.
it uses a lot of memory resources because you have to replace the "First" values with the "second" values and so on.
so, for the Nextion, 4 arrays of 255 bytes for 4 slopes

a small examples from Bascomforum.de (write by djmsc)
all values are rotated

Dim Mein_array(25) As Byte
Dim Temp1 As Byte , Temp2 As Byte , I As Byte
Temp1 = Mein_array(1)
For I = 1 To 24
Temp2 = Mein_array(i + 1)
Mein_array(i) = Temp2
Next I
Mein_array(25) = Temp1

JP
Wink

Netzman · Joined: 25 Nov 2005 Posts: 131 Location: Graz

Other keywords are circular buffer or ring buffer.

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Thank you for the example.
But the problem is not that I did not work it out its speed
It needs to be very fast
4 x 255 byte buffers
so lots of cycles it needs to be in Assembler
Also the M1284p with 16k of ram may be the CPU to use.

I have it working here.
You can see I tried memcopy but it needs two arrays it does not work on the same array.

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Here is a Nextion turned into a data terminal

Regards Paul

albertsm · Joined: 09 Apr 2004 Posts: 5920 Location: Holland

ok, that is simple :