Logic Level shifter for 12864 display on Duet 2 Wifi

[pixelpieper]

Well, it is alive. Turns out the display likes a nonactive reset to work - go figure.

Seems we can use the high active ST7920 chip select for this purpose.

[seraser]

@pixelpieper can this solution be applied to duetwifi?

[pixelpieper]

@seraser this is not maestro specific - the lcd reset pin of the mini 12864 has to be somehow pulled high in order to have the display leave its reset.

@dc42 from the firmware side: when configured as M918 P2, are we guaranteed that the then not functional active high chip select on the maestro display connector stays always high? I.e. is it safe to use as the reset pin?

[Schmart]

@pixelpieper said in Logic Level shifter for 12864 display on Duet 2 Wifi:

nonactive reset

Congratulations, great find! It's nice to see you also have the right tooling at hand to do the troubleshooting Apologies that I couldn't help you with this one, I don't have any Fysetc displays, and the Creality display I tested with doesn't need a reset.

As for your question to use the CS as RESET; does your display also work correctly when the reset pin is permanently tied to Vcc or does the reset signal need a delay?

[seraser]

@dc42 finally working duetwifi, after all pins connected without any modification.

Edit: enter key pushing encoder dont work

[dc42]

@pixelpieper said in Logic Level shifter for 12864 display on Duet 2 Wifi:

@seraser this is not maestro specific - the lcd reset pin of the mini 12864 has to be somehow pulled high in order to have the display leave its reset.

@dc42 from the firmware side: when configured as M918 P2, are we guaranteed that the then not functional active high chip select on the maestro display connector stays always high? I.e. is it safe to use as the reset pin?

Yes, it should be.

[seraser]

@Schmart now is working fine but no enter key detected when press encoder, what can I check?

Rotate work.

Thank you.

[A Former User]

@seraser said in Logic Level shifter for 12864 display on Duet 2 Wifi:

no enter key detected

thats just a switch wired to EncoderPinSw so check the wiring and or voltage on the signal with the key pressed and not pressed?

[seraser]

@bearer will check this night, thank you.

[seraser]

@bearer thank you swaped beep with enc_sw and now LCD work fine but no sd card detected, checked and checked and checked wires and all are fine for sure and m122 only reports sdcard0.

[seraser]

Cs, miso, mosi and csk are fine connected and with 3v3 volts, tomorrow I will check trafic with my oscilloscope.

[seraser]

@pixelpieper your LCD detect sdcard?

Maybe the problem is related to CD(card detect) pin 2.4 exp2 in LCD with no way to duet.

[Schmart]

@seraser I don't think the card detect is the problem. From the Fysetc schematic, it's just a simple switch without other connections and the Duet doesn't need a card detect signal.

If you have SPI traffic correctly coming out the Duet, maybe try a high quality SD card or use shorter or twisted cables for the connection to the display.

Also, you mention using 3.3V as supply voltage? I think you need to use 5V. There should be a voltage regulator on the display PCB that converts the 5V supply voltage to 3.3V. There's even a 74HC4050 buffer that protects the SD card's inputs.

[seraser]

@Schmart power supply is 5v.

Tested three sdcards.

Short dupont connections, checked fine.

Maybe with initial bad connections 74HC4050 is damaged.

I will replace with donor board to test.

[pixelpieper]

@seraser I haven't tried, did not even wire it up and I don't know whether I would bother since I don't use sneakernet to get my gcode onto the printer

[seraser]

Replaced 74HC4050 and same here so stoping because I think is software related sd no detection.

[Schmart]

@seraser you mentioned wanting to check traffic with your oscilloscope, and I mentioned checking SPI traffic coming from the Duet board first as well. I hope you did that before replacing chips? What was the outcome? I think only then we can look for other suspects like the firmware.

[seraser]

@Schmart finally, with relax, checked fine with my ancient hameg, miso, csk and cs are high at 3v3 with and without sdcard but no variations when insert sdcard so this signals are dead an mosi is down with 0v and dead constantly with or without sdcard.

Tested in fysetc 1.2 and fysetc 2.1 because 2.1 works but no light and I can see content.

[seraser]

@Schmart @dc42 we need cs low for set miso high and begin comunication, right? I do not know for sure if duet work with this condition.

[dc42]

@seraser said in Logic Level shifter for 12864 display on Duet 2 Wifi:

@Schmart @dc42 we need cs low for set miso high and begin comunication, right? I do not know for sure if duet work with this condition.

Are you talking about communication with the SD card or with the display?