Guys, I am stuck.
I have an Arduino Zero to talk to a 4.3" enhanced Nextion display, without making use of the Nextion library. That does not matter, though, as I am stuck at the very beginning already.
I have uploaded my screen design via SD card - works fine.
I connected the Rx/Tx lines crossed to the Serial1 Tx/Rx on the Zero.
I set the Serial1 baud rate to 9600 (when uploading a screen from SD, the Nextion informally also says 9600).
I checked the Serial1 with another device - works.
I do not get any result when trying to communicate with the Nextion. Not a single bit.
The only thing I could think of is a mismatch in logic levels: the Zero runs on 3.3V. Do I need a level shifter here?
RX/TX will accept 3.3V logic, but ensure the Display is being powered at 5.0V. Ensure grounds are common.
The Prolific USB to Serial is a good cable
Has it ever functioned over serial?
Could the issue be that you are using an Analog Pin,
Maybe ensure you are using digital pins - check Zero docs
Try SoftwareSerial if needed
I think if the Nextion is accepting the TFT via microSD, the mcu on the Nextion is not fried
It is rare for the USART module to be fried and not the MCU
We'll keep troubleshooting.
I don't know much about the Zero in special ... but can it be, that the parameters of your serial communication are just the wrong? Not the Baudrate, I think more about the signals related, like the signal-polarity ...
TRUE(always driven) (that's what the display need, with 8,n,1)
INVERTED (always driven) (that's what a real PC RS232 expect)
TRUE (open drain, driven high)
INVERTED (open source, driven low)
just another thought ...