Logic Level shifter for 12864 display on Duet 2 Wifi

dc42

Update: I just tried a build with the 12864 display enabled. It overflowed by 28 bytes! So it's close to fitting.

A Former User

just occured to me, would adding both say DIP and SOIC footprint cause issues with signaling? if not, maybe it could lower the diy threshold a little, although SOIC shouldn't really be an issue for the beginner.

oliof

Funny story, the TXS0108 I ordered in DIP format came as SOIC on a PCB with pin headers ... same footprint, but kind of ironic.

oliof

@dc42 I was considering removing kinematics I don't need for the machine I want to run this on because it will likely be the easiest self-contained change for someone not super acquainted with the firmware. But finding another 28 bytes to drop seems a worthy cause (-:

A Former User

eBay is like a box of chocolates?

btw, compiling without, say hangprinter , results in a binary after dc42's other improvements. seemed the path of least resistance.

diff --git a/src/Movement/Kinematics/Kinematics.cpp b/src/Movement/Kinematics/Kinematics.cpp
index 782bd43f..d48ef90f 100644
--- a/src/Movement/Kinematics/Kinematics.cpp
+++ b/src/Movement/Kinematics/Kinematics.cpp
@@ -11,7 +11,9 @@
 #include "LinearDeltaKinematics.h"
 #include "RotaryDeltaKinematics.h"
 #include "ScaraKinematics.h"
+#ifndef SUPPORT_12864_LCD
 #include "HangprinterKinematics.h"
+#endif
 #include "PolarKinematics.h"
 #include "FiveBarScaraKinematics.h"

@@ -161,8 +163,10 @@ AxesBitmap Kinematics::GetConnectedAxes(size_t axis) const noexcept
                return new LinearDeltaKinematics();
        case KinematicsType::scara:
                return new ScaraKinematics();
+#ifndef SUPPORT_12864_LCD
        case KinematicsType::hangprinter:
                return new HangprinterKinematics();
+#endif
        case KinematicsType::polar:
                return new PolarKinematics();
        case KinematicsType::rotaryDelta:
diff --git a/src/Movement/Kinematics/Kinematics.h b/src/Movement/Kinematics/Kinematics.h
index e2cf603f..6852214e 100644
--- a/src/Movement/Kinematics/Kinematics.h
+++ b/src/Movement/Kinematics/Kinematics.h
@@ -27,7 +27,9 @@ enum class KinematicsType : uint8_t
        linearDelta,
        scara,
        coreXYU,
+#ifndef SUPPORT_12864_LCD
        hangprinter,
+#endif
        polar,
        coreXYUV,
        fiveBarScara,           // was previously reserved for @sga, see https://forum.duet3d.com/topic/5775/aditional-carterian-z-axis-on-delta-printer

oliof

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

but it doesn't build at all unless the pins are defined?

I defined the freed pins from the stepper, so they weren't undefined. I just didn't sort them out. I'll give your patch a go and see whether I can get the 28 byte overflow.

oliof

After some more fighting with Eclipse, I seem to have a finished build from RepRapFirmware v3.01-dev branch with LCD support and no hangprinter ... will try to see whether my Duet2 board boots, and then carefully start a test setup ...

A Former User

Took a while before I realized I had to go via 3.0 release to get the iap file to support the 3.x binaries; and then make the swap of the two pins I did on mine - but seems to work with RRF3 as well after Davids efforts.

The dedication on that man ... can we (temporarily!) put him to work on a covid-19 vaccine?

oliof

I am currently trying to understand your tsx cabling -- my 74hct08 started smelling funny after a minute when I tried to figure out what to connect where so I don't trust it a lot. Of course I am complicating things by using an 12864 minipanel which might not even work fine (but in testing lit up fine on 3.3V -- that may be just the leds though).

oliof

Also, some confusion: In your photo you are connecting to the CONN_SD port, not to the CONN_LCD one. Or am I looking at things wrong?

A Former User

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

Also, some confusion: In your photo you are connecting to the CONN_SD port, not to the CONN_LCD one. Or am I looking at things wrong?

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

edit: i would propose swapping lcd_cs to from PortDPin(21) / lcdconn.10 to PortAPin(7) / sdconn.7 as it would enable a single 10 way ribbon cable to function as just a display + sd reader (but no buttons/beep). Or maybe utxd0, urxd0 and spi0_cs could be used if the reader isn't present or needed.

true story. the SPI bus is on CONN_SD

A Former User

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

I am currently trying to understand your tsx cabling -- my 74hct08 started smelling funny

the only difference is the swapping of the LCD_CS pin as it allowed me to use just the one port and also cleaned up the board layout a little. i could probably get below 3 vias if I really put some more effort into it, but with the prices jlcpcb have these days meh.

funny smelling wouldn't be caused by swapping the signal pins they don't have the oompfh to do so. i'd check the 5v and gnd connections.

oliof

It might be a mistake on my board. My guess is I can try to get it to work like your setup, and then move to my board or the updated design later.

I think the distribution of pins to headers is just what a standard 12864 display has, and not dc42's design. I'd suggest sticking with the standard setup.

Don't you need both headers still if you also want to use the encoder wheel? I'd question the utility of the 12864 display without one ... but I might be completely wrong. Speaking of the encoder, do I interpret your color scheme correctly that ENC_A, ENC_B, ENC_SW do not go through the level shifter but connect directly?

A Former User

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

Don't you need both headers still if you also want to use the encoder wheel?

i find my self looking at the screen in passing more than using them for operation, but yes.

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

do I interpret your color scheme correctly that ENC_A, ENC_B, ENC_SW do not go through the level shifter but connect directly?

when i looked at he reprap discount display schematic, the encoder is wired directly to the headers and its effectively three normally open(?) switches to ground so it only needs the pull up on the duet, no level shifting. so yes.

dc42

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

I think the distribution of pins to headers is just what a standard 12864 display has, and not dc42's design.

Correct, the pinout is taken from the original RepRapDiscount design and is compatible with the many clones of that display that you can find on Amazon and eBay. Unfortunately, some printer/display manufacturers got the connectors the wrong way round, and others went for a different pinout completely.

oliof

@dc42 as I am currently experiencing with my CR 20 "minipanel". Reading Marlin source code I am 90% sure it is an ST7920, but for some reason it needs 8MHz instead of 2 (or at least the refresh rate in Marlin is set to 125nsec), and I think some pins are different. I am still digging (-:

A Former User

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

it needs 8MHz instead of 2

should be possible to do with F8000000 to the M918 command

for the pinout you could look at reprap http://reprap.org/mediawiki/images/5/51/RRD_FULL_GRAPHIC_SMART_CONTROLER_SCHEMATIC.pdf and work backwards from the 3 pins on the lcd and the pins on the encoder (to map the cr 20 header)?

oliof

Thanks for pointing out the F parameter! I will use the default pin layout if only to avoid future hassle when a ready-made adapter is available and people use this that aren't up to making their own custom cable (especially considering I have enough trouble doing it myself).

A new reprap smart controller is on the way so I can test with a device that's known good ... I will test first on an unmodified maestro running RRF 2.05.

A Former User

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

I will use the default pin layout

not sure which is the default? afaik beyond the reprap one its a bit of a lottery, and ramps have had a range of adapters for the various clones (why they couldn't just clone the reprap idk)

if you're refering to the change i made, it's only between the duet and the 74htc08 so it won't affect the display as such. (but it will simplify troubleshooting as you only need to get 1 cable right to get the display to indicate its working)

oliof

The reprap one works for my favorite replacement display BTT TFT24/35 in 12864 emulation mode) (-: but you're right it -- doesn't matter for the the display side.