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fabio2018
Joined: 07 Sep 2017
Posts: 3
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| Send and receive data from the Nextion serial display |
 Posted: Sun Jul 22, 2018 2:32 pm |
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Hello people,
I have this code below that I want to use to receive data from the nextion, but I cant receive data when the button is triggered. When I send data does not work. Does not work the 2 together send and receive. Could someone give me a solution:
| Code: |
int conta;
int valor;
while(true) {
d=getc(); //recebe dados do display nextion
if(d==1020){
printf(lcd_putc,"\acionada");
}
if (input(PIN_a3)){
conta=conta+1;//envia dados da variavel conta para display nextion
printf("n1.val=");
printf("%u",valor);
printf("ÿÿÿ");
}
if(input(PIN_a2)){
conta=conta-1;
printf("n1.val=");
printf("%u",valor);
printf("ÿÿÿ");
}
} |
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temtronic
Joined: 01 Jul 2010
Posts: 9241
Location: Greensville,Ontario
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| Posted: Sun Jul 22, 2018 3:01 pm |
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We need to know a few things..
1) What PIC are you using ?
2) Is that display a 3 volt or 5 volt device ?
Odds are it's really a 3 volt device ( '1' and '0' on the data lines are 3 volt ). I seem to recall the signal lines are '5 volt tolerant' BUT signalling is 0, 3 volts.
If true then you should use a PIC that will run at 3 volts at the desired speed. That means choosing a PIC with an 'L' in the device, like 16LF1234 NOT a 16F1234. Be sure to check the electrical specs section of the datasheet ! There are some PICs that will work from 3 to 5 volts though.
Search the 'code library' as well as this forum for 'Nextion', you should get a few hits.
Also be sure your power supply has sufficient current to run the display ! Often overlooked it is important !
edit: I was curious(and don't want to go out in 90*F sun...), so I downloaded the datasheet for the 1st model.CONFIRMED that data lines( send, receive) ARE 3 volt logic levels.
Jay
Last edited by temtronic on Mon Jul 23, 2018 7:04 am; edited 1 time in total |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19537
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| Posted: Mon Jul 23, 2018 12:54 am |
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Other things:
The displays specifically say they require a minimum of 5mSec before being sent data. This is also from the point when they wake, not the PIC. PIC's habitually start to wake before a lot of other chips. You need perhaps a 100mSec wait at the start of your code.
All commands need to be terminated by \xFF\xFF\xFF. You are using the "ÿÿÿ" sequence, which 'may' generate this, but this is dependant on your system character set. Unless you are sure this is generating the hex FF sequence better to use the hex escaped sequence.
You are sending the variable 'valor', but do not initialise it. It could contain anything....
Your commands put 'valor' into the variable 'n1' on the display. However nothing is written to the screen. You are not sending any command to physically display this.
You have no receive serial commands, so you are not going to receive anything from the display. |
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