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Prusa changed main board in MINI+  

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BogdanH
(@bogdanh)
Reputable Member
Prusa changed main board in MINI+

I received MINI+ about two weeks ago. As it turned out, Prusa decided to use modified main board without mentioning that in documentation.
The main difference (visible at least) is, that one of the three pins on board is missing:
Prusa - flashing custom firmware
-in this case, the missing pin is the one, that should be closer to the center of the board.

Because that pin is missing, user obviously can't put jumper on it, to enable loading custom firmware (as described in above link). In that sense, providing opens source firmware is of no benefit if user can't use it. And without custom firmware, it's impossible to use M500 code.

To keep post short: in case of MINI upgrade (i.e. Bondtech extruder & heatbreak), it will remain impossible to store necessary parameters permanently into EEPROM.

I was in contact with Prusa support, where board change was confirmed. However, on my question how to proceed, no solution was suggested. Instead, I was pointed to GitHub (feature request), where I realized there's not much going on since August last year.

Wish you all a nice day

Mini+ with Bondtech upgrade & modified firmware...
Posted : 26/05/2021 10:41 am
Lukerson liked
Lukerson
(@lukerson)
New Member
RE: Prusa changed main board in MINI+

Just break the appendix if the board has only two instead of 3 pins.

Then when you try to upload the FW, a warning will pop up -> just skip.

when i try put a jumper to this two pins my printer when power on wont work. When i remove this jumper and want to start and flash custom fw (only change esteps for bondtech) i just only confirm warning that i going to flash unofficial FW thats all

 

This post was modified 4 months ago 2 times by Lukerson
Posted : 27/05/2021 11:19 am
BogdanH
(@bogdanh)
Reputable Member
Topic starter answered:
RE: Prusa changed main board in MINI+

Thank you very much for that info!
I already removed appendix (before I realized board only has two pins for jumper) and when I used jumper on two remaining pins, printer didn't boot either -so I removed jumper.

So, now I need to jump into modifying firmware and somehow compile it... To tell the truth, I didn't expect so much hassle when I decided for Mini.

Thanks again -very appreciated.

Mini+ with Bondtech upgrade & modified firmware...
Posted : 27/05/2021 1:03 pm
Lukerson
(@lukerson)
New Member
RE: Prusa changed main board in MINI+

You're welcome 🖐️ 🤩 

Posted : 28/05/2021 8:09 am
BogdanH
(@bogdanh)
Reputable Member
Topic starter answered:
RE: Prusa changed main board in MINI+

I have problem with setting new PID value into firmware. In configuration file I have set the following (for Bondtech heatbreak):

#define DEFAULT_Kp 13.54 // original is 7.00
#define DEFAULT_Ki 0.98 // original is 0.50
#define DEFAULT_Kd 46.58 // original is 45.00

After firmware update, I have checked current settings (with Pronterface) by using M503 command, and I still get old (original) PID values. However, if I execute M501 command (read parameters from EEPROM) or M502 (restore default settings), PID values for Bondtech are set as current. Obviously, I wish that new PID values will be used by default (as current values) after power-on. How can I achieve that?
Btw. new E-step value works as expected after power-on.

Mini+ with Bondtech upgrade & modified firmware...
Posted : 28/05/2021 10:09 am
BogdanH
(@bogdanh)
Reputable Member
Topic starter answered:
RE: Prusa changed main board in MINI+

Update on my previous post (as I didn't found option to edit it).

I managed to store new PID values which are now used as default values after power-on. Now, that my Mini is in the state I wanted it to be, it's finally time for me to open that Haribo bag.

For those who consider buying Mini...
No, it doesn't work out of the box (unless you're extremely lucky). Before even turning printer on for the first time, check printer geometry: especially angle between (print bed) x-axis and z-axis. Even very little deviation (i.e. only 0.6deg) will probably make first layer calibration impossible.
I also couldn't find anywhere exact distance between PINDA and tip of the nozzle: some documentations suggest 0,8mm (or using credit card), or using zip tie (gives about 1mm), etc. -which, at least for SuperPINDA, is too small (unless you're happy with z-offset very close to -2.00 limit).
It's no secret anymore, that (Bondtech) heatbreak is very much recommended upgrade -is a mystery to me why Prusa doesn't implement it. Anyway, it doesn't cost much and is of real benefit.
And here we come to firmware... To keep warranty, one needs to load necessary G-code after every power on. I know "put it in Prusa slicer" -but that solution is of no use in some situations (i.e. first layer calibration) and is not practical in general. And so, many break the warranty (appendix, that is) just to be able to use necessary upgrade in a friendly way -assuming, they know how to change data in firmware source and then compile it.
Conclusion... if you plan to make upgrades on Mini (and you will, sooner or later), then be prepared for some obstacles.

Ok, now let me check that Haribo...

Mini+ with Bondtech upgrade & modified firmware...
Posted : 29/05/2021 3:25 pm
Rafx liked
matthewlloyd
(@matthewlloyd)
Active Member
RE: Prusa changed main board in MINI+
Posted by: @bogdanh

Thank you very much for that info!
I already removed appendix (before I realized board only has two pins for jumper) and when I used jumper on two remaining pins, printer didn't boot either -so I removed jumper.

So, now I need to jump into modifying firmware and somehow compile it... To tell the truth, I didn't expect so much hassle when I decided for Mini.

Thanks again -very appreciated.

It turns out these two pins are still useful. If you have broken your appendix and you put a jumper there, the chip boots directly into DFU mode. You can then connect to it by micro-USB and flash it using dfu-util. This is useful if you have flashed firmware that somehow accidentally prevents normal startup and bricks the board, since it bypasses Prusa's bootloader and initialization sequence entirely.

Posted : 03/06/2021 5:53 am
matthewlloyd
(@matthewlloyd)
Active Member
RE: Prusa changed main board in MINI+
Posted by: @bogdanh

I have problem with setting new PID value into firmware. In configuration file I have set the following (for Bondtech heatbreak):

#define DEFAULT_Kp 13.54 // original is 7.00
#define DEFAULT_Ki 0.98 // original is 0.50
#define DEFAULT_Kd 46.58 // original is 45.00

After firmware update, I have checked current settings (with Pronterface) by using M503 command, and I still get old (original) PID values. However, if I execute M501 command (read parameters from EEPROM) or M502 (restore default settings), PID values for Bondtech are set as current. Obviously, I wish that new PID values will be used by default (as current values) after power-on. How can I achieve that?
Btw. new E-step value works as expected after power-on.

The default firmware does not ask Marlin to load its EEPROM settings on startup. I created a patch to reenable Marlin EEPROM settings here:

https://gist.github.com/matthewlloyd/341907f5c20790371c3ca2df4426639b/edit

The Prusa code will still override the PID values because it controls them independently from Marlin:

https://github.com/prusa3d/Prusa-Firmware-Buddy/blob/7b9a56a11f5f2e4a38a6d022e8fb338f840436d0/src/common/marlin_server.cpp#L393

Posted : 03/06/2021 5:56 am
BogdanH
(@bogdanh)
Reputable Member
Topic starter answered:
RE: Prusa changed main board in MINI+

hello matthewlloyd,

Thank you for additional info. Truth to be told, I'm not that much of an expert in this matter (but I get the idea behind) -anyway, it's good to know what purpose those two pins serve. My Bondtech upgraded Mini now works the way I wanted it to (that is, no need to load G-code at every power on) and so I'll try to resist any further "experiments" -unless it turns out I have no choice.

Btw. link you gave (gist.github.com/matthewlloyd/...) leads to "Page not found".

Thank you again for showing interest on my issue.

Mini+ with Bondtech upgrade & modified firmware...
Posted : 03/06/2021 8:38 am
matthewlloyd
(@matthewlloyd)
Active Member
RE: Prusa changed main board in MINI+
Posted by: @bogdanh

Btw. link you gave (gist.github.com/matthewlloyd/...) leads to "Page not found".

Here's the correct link: https://gist.github.com/matthewlloyd/341907f5c20790371c3ca2df4426639b

Posted : 03/06/2021 5:16 pm
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