Hello
I got problems with the 1.54 inch E-Ink display V2 and ESP8266.
If GPIO 15 (SS) ist connected, ESP won't boot.
If I disconnect it, it will boot
But to work properly, I have to connect it , right?
I tried a NodeMCU and a Wemos D1 mini.
I read, that pulling the GPIO 15 to GND with a resistor would help, but I saw so many projects on the net with ESPs and the Waveshare displays and none of them used a resistor!
Just connected it and it worked.
Any help appreciated!
Try a 2k4 resistor between GPIO15 and ground. The exact value doesn't matter, probably anything between 1k0 and 5k0 will work, possibly even 10k, not sure.
If you connect GPIO15 as a serial port you will have this problem as the serial port tends to pull it high.
I had problems with ESP8266s not starting reliable until I added the resistor.
On boot GPIO 15 held high tells it to boot from external flash (AFAIK, anyway, the resistor fixes the problem).
Thanks I will try the resistor.
Meanwhile I found out, that the CS Pin can be mapped to another pin on the ESP.
Could I use D0 on the Wemos D1 Mini?
And if yes, I would surely need to declare that I’m sketch wouldn’t I? But how?
michaelwsw5:
Meanwhile I found out, that the CS Pin can be mapped to another pin on the ESP.
Could I use D0 on the Wemos D1 Mini?
And if yes, I would surely need to declare that I’m sketch wouldn’t I? But how?
I don't know. I didn't know you could do that. That would be useful for me if it's possible and I knew how to do it! If you find out please explain how here, or if you have half an idea how then share that and I'll see if I can make sense of it.
Thanks.
welcome to the forum. Please read General Guidance and How to use the Forum.
If you mention e-paper in the topic title, you get my attention faster.
If you mention the library you use, the e-paper you use (Waveshare 1.54" b/w V2 with board) with clickable link, connection board (or panel is mounted on board, V2), and processor board, you can get a faster and complete answer.
You need to tell the library which pins you use. That's all I can say without knowing which library you use.
You can use D0, but that prevents you to use D0 for processor reset, if you ever want to use processor deep sleep.
The issue with CS on GPIO15 comes from the level converter on the V2 board. The processor internal pull-down resistor is too weak for the load (pulll-up effect towards middle voltage of the bidirectional converter). Additional 2k4 pull-down is a good choice, should be enough.
I read, that pulling the GPIO 15 to GND with a resistor would help, but I saw so many projects on the net with ESPs and the Waveshare displays and none of them used a resistor!
The earlier e-paper boards from Waveshare didn't have level converters.
BTW: you can use any (free) pin for CS, but you can't use the SS pin for anything else, if you use HW SPI. This is true for several processors or SPIClass implementations.
Jean-Marc
Hello Jean-Marc and thank you for your Reply.
I will follow your suggestions next time regarding Topic name and providing details.
In deed I tried GxEPD2 and several other libraries.
Your explanation with the level converter is satisfying for me as I now do know where to start.
I will try both methods (resistor and choosing another pin) over the next days when possible!
The best
OK just a quick update:
I managed to get it working without wiring a resistor.
I changed the PIN definition in the sketch, so that D0 of the Wemos D1 mini is used for CS.
That did the trick!
Thanks everyone!
michaelwsw5:
I managed to get it working without wiring a resistor.
I changed the PIN definition in the sketch, so that D0 of the Wemos D1 mini is used for CS.
Please will you post the code for how you did this, both for my benefit and for the benefit of anyone reading this in future.
Thanks.