Unofficial Nextion/TJC User Forum

Sendme Command problem

Does anyone else maybe have a problem in the latest Nextion version with the “sendme” command?
I use gui software for programming MCU’s and according to me the problem will
more likely be on the gui side of the Software than Nextion.
But I thought I would ask here just to be sure anyone else doesn’t have the same problem.
It have worked fine in previous versions of the gui but it seems to not work now no matter what I do.

To issue à “send me” you’ll have to transmit “sendme” over serial, followed by the terminator (3 times 0xFF).
Depending on the setting of the bkcmd variable, there will be an acknowledgement or an error code first:
bkcmd=0 —> no extra return
bkcmd=1 —> 0x01 0xFF 0xFF 0xFF (command successful) or nothing in case of error
bkcmd=2 —> 0xnn 0xFF 0xFF 0xFF where 0xnn is an error code indicating the problem or nothing in case of succes
bkcmd=3 —> Like bkcmd =2 and 1 at the same time, will always send either 0x01 or an error code, followed by 3 times 0xFF, depending on success or fail.
After this, the Nextion then replies with 5 bytes in return:
0x66 to indicate that a page number will follow
0xnn the current page number
0xFF three times a a terminator.

You should always set bkcmd=3 to obtain a qualified response on every command which you transmit to the Nextion before you get the expected return value (if your command expects one).
I’m not sure if this meticulous way of handling and debugging the communication, catching error conditions and acknowledgements can be done with GUI programming tools. To me, these are like painting by numbers - give something close to the desired result but not the optimum. I strongly recommend keeping the control over each single byte by writing your code in C/C++. There are enough tutorials on the internet and on the Nextion website to allow you a quick start.

Thanks for the reply, you are right I will do as you suggested. That is a easy way to determine on which side the problem is, I did not think of it.
Thanks again, appreciate your assistance.


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