How to send raw commands via SerialBridge to Nextion displays?

[renne]

• Searched the problem in issues
• Hardware used : Electrodragon ESP8266 SMD Adapter Breakout Boards R3.0 + Nextion NX4024T032_011 display

Nextion displays use a sequence of 3x 0xFF as delimiter. I want to use SerialBridge via MQTT with Node-Red:

backlog Baudrate 9600; SerialDelimiter 255; SerialSend3 h0.val=75\0xFF\0xFF\0xFF;

does not work. The display does not react while the command works in linux with minicom and a USB-UART adapter.

08:36:21 CMD: backlog Baudrate 9600; SerialDelimiter 255; SerialSend3 h0.val=75\0xFF\0xFF\0xFF;
08:36:21 SRC: WebConsole from 192.168.100.30
08:36:21 RSL: Received Topic /backlog, Data Size 73, Data Baudrate 9600; SerialDelimiter 255; SerialSend3 h0.val=75\0xFF\0xFF\0xFF;
08:36:21 RSL: Group 0, Index 1, Command BACKLOG, Data Baudrate 9600; SerialDelimiter 255; SerialSend3 h0.val=75\0xFF\0xFF\0xFF;
08:36:21 SRC: Backlog
08:36:21 RSL: Received Topic /Baudrate, Data Size 4, Data 9600
08:36:21 RSL: Group 0, Index 1, Command BAUDRATE, Data 9600
08:36:21 APP: Set Baudrate to 9600
08:36:21 MQT: stat/sonoff/RESULT = {"Baudrate":9600}
08:36:21 SRC: Backlog
08:36:21 RSL: Received Topic /SerialDelimiter, Data Size 3, Data 255
08:36:21 RSL: Group 0, Index 1, Command SERIALDELIMITER, Data 255
08:36:21 MQT: stat/sonoff/RESULT = {"SerialDelimiter":255}
08:36:21 SRC: Backlog
08:36:21 RSL: Received Topic /SerialSend3, Data Size 24, Data h0.val=75\0xFF\0xFF\0xFF
08:36:21 RSL: Group 0, Index 3, Command SERIALSEND, Data h0.val=75\0xFF\0xFF\0xFF
08:36:21 MQT: stat/sonoff/RESULT = {"SerialSend":"Done"}
08:36:22 CFG: Saved to flash at F7, Count 10, Bytes 3584

Does anyone have an idea what's wrong with the command?

[Jason2866]

Hallo Renne,

i think as SerialDelimiter is only 1 Character possible. So SerialSend3 wont work here.
May you try SerialSend4 (Raw Serial Send)

[ascillato2]

Hi,

@renne

SerialSend4 had worked for you?

[ascillato2]

Hi,

Closing this issue as there is no feedback. Please, ask to reopen if needed. Thanks.

[renne]

@ascillato2
No, SerialSend4 does not work because of the triple 0xff as delimiter.
I've started working on a Nextion-specific MQTT-softserial bridge.

[gitolicious]

I also tried this but failed with SerialSend3... I switched to calculating the hex values in node-red and sending them via SerialSend5. A function node is doing the following converstion:

// str to hex
msg.payload = Buffer.from(msg.payload,'ascii').toString('hex');

// append delimiter
msg.payload += 'ffffff';

return msg;

Works, but is kind of unfortunate as the documentation of SerialSend3 looks like it should actually support \0xFF\0xFF\0xFF

@renne @martinmatias Any more progress on your side?

[GianCann]

Hi to all,

I'm trying to figure out how to send commands to the Nextion, via Serial Send.
@gitolicious can you confirm that command like txtStatus.txt="Hello word" it's possible to send with this command?:

SerialSend5 7478745374617475732e7478743d2248656c6c6f20576f726c6422FFFFFF

Where 74 78 74 53 74 61 74 75 73 2e 74 78 74 3d 22 48 65 6c 6c 6f 20 57 6f 72 6c 64 22 is hex conversion of txtStatus.txt="Hello word"

However, if it were possible to send the Nextion command in Ascii format, adding the FF FF FF delimiter, would be optimal...

I want to use Tasmota to 'talk' with Nextion Display (via Serial Bridge) because i've a ESP12 in a place that execute only a single task (relay activation) ad i want to use also to display status & value from another device via MQTT.

I hope to see good news on this topic ;)

[GianCann]

@ascillato can you reopen this issue?

[gitolicious]

Yes, for me it is working without any problems with the above str2hex conversion.
I am using the regular RX/TX pins of my NodeMCU though. Haven't tried Software Serial Bridge. As I am only doing OTA updates, I don't need RX/TX for anything else and have the generic GPIOs free for other purposes.

[GianCann]

Ok, thank you @gitolicious
But i don't want to use Node-Red...
Software Serial Bridge seems to not support SerialSend4 command but, for me, is not a problem because i don't need hardware serial for other purpose.

However, if the Tasmota guys explain how to send 0xFF 0xFF 0xFF without hexadecimal conversion, it's much better ;)

[gitolicious]

You can do the conversion also anywhere else, doesn't need to be node-red. Where does your txtStatus.txt="Hello word" text originate from? Maybe there you can hex-encode it.

[GianCann]

I use Home Assistant and i don't find the way to convert string in hex data, in a template/automation.

[gitolicious]

Sorry, can't be of any help there. I am also using Home Assistant but all the automation/logic part is in node-red.

[GianCann]

I try to put an eye to Node Red, but only for a sigle string-to-hex formatting seems to shot a mosquito with a bazooka :)

I hope in a smart (ad simple) solution from Tasmota Team!

[gitolicious]

Sure, you are right on that...
I had a look into the code but my C skills are not that great. It is somewhere along the lines of

https://github.com/arendst/Sonoff-Tasmota/blob/15e4918238e49e6e8d6ce504b2e0786e49387447/sonoff/sonoff.ino#L1060-L1069

What confuses me is that the documentation states that number values 128-255 would disable the delimiter. Looking at the implementation I don't think that's true...

Now for our problem, probably a new SerialDelimiter2 command would need to be introduced accepting multi-character hex delimiters...? Or make the current implementation "hex-aware" by looking for .startsWith("0x").

[ascillato2]

Reopened as requested by @GianCann

[GianCann]

The night sleep has bring to me a tip..
Today, i try to send "ÿÿÿ" string at the end of command string.
The "ÿ" char is ascii convertion of 0xFF value (255 in decimal).

[GianCann]

it seemed too simple ...

SSerialSend2 g0.dis=10ÿÿÿ
07:51:22 CMD:
07:51:22 RSL: stat/pioggia/RESULT = {"Command":"Unknown"}

Sending ÿÿÿ don't work :(

[gitolicious]

Too bad. Did you check what has actually been sent out on a hex level? (Should be easy to do so with a serial usb adapter.)
What I saw is that when you do SerialDelimiter ÿ it is setting it to 193, not 255. Sounds fishy to me.

[GianCann]

(Should be easy to do so with a serial usb adapter.)

Can you explain how to do?

What I saw is that when you do SerialDelimiter ÿ it is setting it to 193, not 255. Sounds fishy to me.

https://httplab.it/ASCIICode

The use of ÿÿÿ are reported also in Nextion documentation
https://nextion.itead.cc/resources/documents/instruction-set/

General Rule or Practice

1 | All instructions over serial: are terminated with three bytes of 0xFF 0xFF 0xFF
ie: decimal: 255  or  hex: 0xFF or  ansichar: ÿ  or binary: 11111111
ie  byte ndt[3] = {255,255,255}; write(ndt,3);  or print(“\xFF\xFF\xFF”);  or  print(“ÿÿÿ”)

[Jason2866]

@GianCann A fault that is often made https://httplab.it/ASCIICode is NOT ASCII Code it is ANSI!
Nextion wrote ANSI...

[GianCann]

AAAAH! I have not read with due attention :(

[gitolicious]

(Should be easy to do so with a serial usb adapter.)

Can you explain how to do?

Connect your ESPs Rx/Tx and GND pins with your USB serial adapter, then any serial monitor of your liking should do. I saw this one being recommended as it has a "hex" switch: https://sites.google.com/site/terminalbpp/
Haven't tried it though.

[gitolicious]

Alright, I installed the terminal tool and sent out SerialSend3 ÿÿÿ. The ÿs are sent out as 0xC3 BF. So this can't work.

Terminal log file
Date: 14.01.2019 - 18:51:03
-----------------------------------------------
C3 BF C3 BF C3 BF 
-----------------------------------------------
Date: 14.01.2019 - 18:51:08
End log file

My last resort as an improvement of the workflow is to send out the following:

Backlog SerialSend3 g0.dis=10; SerialSend5 FFFFFF

By this you save yourself translating the command to hex. Need to take care of encoding though as Nextion doesn't understand UTF-8 but only ASCII.

@Jason2866 I don't really get the implications of what you are saying...

[Jason2866]

@gitolicious
I just say that ANSI code is not equal ASCII code

[GianCann]

The Nextion display is a very powerfull (and simple to program) HMI device with touch screen.

At the end, to integrate this device in Tasmota, without sending double Serial Send command, is needed just a simple SetOptionXX 1/0 to activate/deactivate the addition of FFFFFF to command string sended via serial bridge.

[GianCann]

Ok, i've make some test...

1. (Software serial bridge - display connected to GPIO4/GPIO5) I've edit the xdrv_08_serial_bridge.ino adding this code in SerialBridgeCommand function and works well:

else if ((CMND_SSERIALSEND == command_code) && (XdrvMailbox.index > 0) && (XdrvMailbox.index <= 4)) {
    if (XdrvMailbox.data_len > 0) {
      if (1 == XdrvMailbox.index) {
        SerialBridgeSerial->write(XdrvMailbox.data, XdrvMailbox.data_len);
        SerialBridgeSerial->write("\n");
      }
      else if (2 == XdrvMailbox.index) {
        SerialBridgeSerial->write(XdrvMailbox.data, XdrvMailbox.data_len);
      }
      else if (3 == XdrvMailbox.index) {
        SerialBridgeSerial->write(Unescape(XdrvMailbox.data, &XdrvMailbox.data_len), XdrvMailbox.data_len);
      }
      //For Nextion LCD Display
      else if (4 == XdrvMailbox.index) {
        SerialBridgeSerial->write(XdrvMailbox.data, XdrvMailbox.data_len);
        SerialBridgeSerial->write(0xFF);
        SerialBridgeSerial->write(0xFF);
        SerialBridgeSerial->write(0xFF);
      }

I send a Nextiot command like this:

SSerialSend4 t0.txt="Hello world from Tasmota"

Note: SSerialSend4 not exist in Tasmota, but only SerialSend4

Nextion elaborate the command and show Hello world from Tasmota in textbox named t0

2. (Hardware serial bridge - display connected to GPIO4/GPIO5) I tried with SerialSend2 (nextion-command) + SerialSend5 FFFFFF but this not work. I believe that the problem is serial debug that in boot time send wrong data (log data) to Nextion.

3. (Hardware serial bridge) I tried with rule do disable serial log on system boot, but nothing to do using Backlog SerialSend2 t0.txt="Prova"; SerialSend5 FFFFFF

At this point, i ask to @arendst if it's possibile to add a SetOption_XX_ 0/1 to add/remove 'FFFFFF' for use SerialSend2/SSerialSend2 in trasparent mode for who use the Nextion display.

[GianCann]

@gitolicious i've open a new feature request:
#4947

[jkrijger67]

Hello,

at the end was there a solution for writing serial Commands to nextion displays?