MKS MINI 12864 on Maestro

crussty

Before I call a party-foul on the hardware, I wanted to inquire here on if there is any reason (or anything I need to change in firmware) to get the MKS MINI 12864 working with a Maestro? (https://reprap.org/wiki/MKS_MINI_12864)?

We have it working with a "standard" full size RepRapDiscount Full Graphic Smart Controller, so it could be bad hardware, but wanted to double check for any known compatibility issues, or changes we would need to make to support it.

Thanks in advance!

Chris

Mabover

Looking at the wiki page on reprap.org it looks like this panel has the same sort of control interface and the same lcd controller as the viki2 lcd panel and mini viki lcd panel. The give away is that there is an A0 pin called out on the interface pin headers.
I asked about getting support for this type of lcd panel in this thread: https://forum.duet3d.com/topic/6467/viki2-lcd-panel-on-maestro/5

I have not had the time to attempt to modify the firmware to support it and it is likely outside my capabilities at this point.
If you capable of making the modifications please do as I would like to use the Viki2 lcd I have.

Otherwise I would be interested talking to @dc42 about financial sponsering the work required to support the Viki2 and similar screens.
If you are interested is helping financially support the effort to get support added to the firmware reply so that way @dc42 knows people are willing to pay to get this added to the firmware.

dc42

We're not planning to add support for any other 12864 displays in the firmware, because the RepRapDiscount 12864 display clones cost only about £10 on Amazon or eBay, and connecting any other display would require a hardware modification or at least a custom-made cable.

Mabover

@dc42 completely understand your position from a user support position, custom cabling is not a problem for me personally but can see where it might be for others. Like I said I am willing to pay for support of this type of lcd to be added to the firmware, feel free to pm to discuss how much it would cost if interested.

Also not sure if you looked up the mks mini display but it goes for about 20 dollars so I wouldn't be surprised if more people come looking for support in the future.

crussty

Rats! Had really hopped this would work as using the mini LCD in our case isn't so much about cost savings, it's size of the board/screen and position of the SD card (front load). If all it required was a custom terminated ribbon cable to make work, that isn't out of the question, but not worth the efforts if it required hardware modifications.

Mabover

What David is referring to in the cable/hardware mod is since the mks mini, Viki2 and similar displays need to have an extra pin, A0, you would have to pull that pin in from somewhere else like from the expansion header for example. It wouldn't be the simple plug in solution that the currently supported display allows for. For me personally it's not an issue as the Viki2 display doesn't come with ribbon cables it had flying leads that you plug in to the specific pins needed.
I am guessing the hardware modification he is mentioning would be something along the lines of running a jumper wire from a pin on the expansion header and soldering it to the bottom of the lcd connect on the pin that the ribbon cable connects to for the pin A0.

Once again I am willing pay for these types of displays to be added because to your point its not a cost consideration for me it's a design and appearance issue for me. I detest the look of the white/grey on blue background of the reprap 12864 display and it also doesn't fit in the location I want to install it on the Flashforge Creator Pro I am converting.

Mabover

I should also say that as above I completely understand what I suspect is David's desire to not create a support headache of people not reading the documentation close enough and asking why the display doesnt't. Then he or someone else has to explain why and what they need to do everyone someone asks about it.

T3P3Tony

Why do the other displays have A0, what is that extra pin used for?

Mabover

@t3p3tony the A0 pin is used as a register select pin, it's used for selecting they type of data being sent to the display command or data.

dc42

Is either the Viki2 or the MKS Mini 12864 open source? I haven't found a schematic for either on the Internet, only one for the Viki 1 20x4 text display.

Mabover

@dc42 The MKS mini unfortunately no, they have a history of not being very friendly in that regard, I did find someone had posted the level converter ic being used is the same 75hc4050 used on the RepRap Full Graphic Smart Controller and its also used on the Viki2.

The reprap wiki lists this pin out for the MKS Mini https://reprap.org/wiki/MKS_MINI_12864

Annoyingly they didn't put the lcd CS pin in the same location as the RepRap display so that would require additional custom wiring. Interestingly they did not put in separate SPI signals lines for the LCD, they are pulling from the SD card SPI lines. To me this suggest that the 74HC4050 is being used to shift the SD card signals as well as the lcd signals but as I do not have one of these displays I can not confirm how the lines are being level shifted.
A person could use use the "dupont" style female - female jumpers instead of the ribbon cable on the EXP1 header connections to make the custom connections if they did not have access to crimpers and a selection of Molex SL series connectors/contact pins to allow for crimping custom connectors.

Panucatt Devices list them selves as being an open hardware company but like you I was unable to find a schematic for the viki2 but there is a wiring diagram available to aid in hooking it up http://panucattdevices.freshdesk.com/support/solutions/articles/1000158562-viki-lcd-2-0-support-files .
Perhaps they might provide the schematic if asked for it, I didn't think about doing that as i was able to work out the needed info from the Viki2 I have in hand.

I looked over my Viki2 and did some quick pin tracing and the 74HC4050 is being used to level shift all the signals and is using a 3.3v VCC into the chip as the display is 3.3v as is the SD card. I looked at the data sheet for the 74HC4050 and it indicates that it will recognize a 2.5v+ signal as a high signal when 3.3v is used for VCC, given that, no level shifting is required for the extra A0 signal that is needed.
The Viki can be setup to accept 5v or 3.3v on its VCC input line, 3.3v is passed through directly and 5v goes into a voltage regulator to produce 3.3v.
The Viki2 also combines the SD and LCD SPI signals together like on the mks mini.

Given that the Viki2 has its own custom pin out for the connectors I had planned on making my own custom cabling to hook it up to the Maestro.

crussty

@mabover that jives with what I have been table to locate on this so far as well from digging through how Marlin supports it.

dc42

What display controller chips do these displays use?

Mabover

@dc42 I know specifically that the Viki2 uses the ST7565 and I suspect the MKS mini does as well from what I have seen online.
Adafruit has some documentation that may be helpful including a datasheet http://www.ladyada.net/learn/lcd/st7565.html

I have also noticed that Marlin specifically is using the u8glib to interface with these displays. From what I can see online for the MKS mini displays people are using the minipanel configuration and in the Marlin defines that configs as being the ST7565 display.