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bigtreetech / BIGTREETECH-SKR-CR6

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Z-stop port voltage incorrect #9

Open WillKendall opened 3 years ago

WillKendall commented 3 years ago

The Z-stop optical sensor that ships on the CR-6 SE is rated for 5v-24v. I have confirmed that the sensor that shipped on my CR-6 SE won't operate below 4v. The voltage on the Z-stop port of the BTT SKR CR6 is 3.3v. This is insufficient voltage to reliably operate the sensor. See the datasheet: https://www.alliedelec.com/m/d/459f9713c1e8270fed68967986fcb396.pdf

IckZ commented 3 years ago

Hm.. I've just get the btt board. Is it possible to raise the voltage through the firmware or do I have to buy an other optical sensor now?

WillKendall commented 3 years ago

You can remove the power wire from the sensor connector at the skr cr-6 and put it onto a 5v pin nearby, just make sure it stays connected. First, I would try it without modification and see how it works. I see videos on YouTube of people using the connector as is and not having any problems with it. I had to compile the latest Marlin cr-6 community firmware to get it to work without modification. That being said, I don't know if the firmware uses the z-stop sensor because without modification it's indicator light doesn't come on. I assume if it doesn't light, it doesn't work. Now that I have the printer in a working state (unmodified) I will hook the sensors power back up to 5v and report back.

On Fri, Jan 22, 2021, 12:02 AM IckZ notifications@github.com wrote:

Hm.. I've just get the btt board. Is it possible to raise the voltage through the firmware or do I have to buy an other optical sensor now?

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/bigtreetech/BIGTREETECH-SKR-CR6/issues/9#issuecomment-765216891, or unsubscribe https://github.com/notifications/unsubscribe-auth/AGYAYGWUBLDMGC4RQIRUPSLS3EWLFANCNFSM4WCYYBYQ .

IckZ commented 3 years ago

Thank you for the feedback. In the meantime I have also read that it should actually only be the status LED that is not working due to the undervoltage.

https://damsteen.nl/blog/2020/11/25/how-to-btt-skr-cr6-installation -> see "Known Issues".

Nevertheless, many thanks for the hint and the tip to simply tap the 5V from a neighboring PIN. But for now I will keep an eye on the function as it is.

oliverhbailey commented 3 years ago

The spec sheet is misleading. plus or minus 10% means minus 10% of 5 volts, or 4.5 volts. plus 10% of 24 volts means is should operate at 26.4 volts. You can't subtract 2.4 volts from 5 volts and expect the unit to work. It's a voltage range not an absolute value. I would be cautious to use more than plus or mins .5 volt.

WillKendall commented 3 years ago

As I said in my initial post, I tested the operation of the LED indicator on the sensor and it did not function below 4v on my unit. I have not tested the sensor to determine whether or not it actually functions below 4v. That being said, I have hooked the power line of the sensor to both 3.3v and 5v and it seems to work either way (using the community Marlin firmware). When I completely disconnect the sensor, the hotend crashes into the bed. So the sensor seems to work on both voltages. However, I do feel that the voltage issue should be fixed in the next revision of the motherboard, since I cannot find any sensors of this type that say they support 3.3v. If it isn't in writing (i.e. a datasheet) the manufacturer of the sensor may change that compatibility at any moment and the printers with that version of the sensor would stop working.

On Mon, Jan 25, 2021 at 8:04 AM Oliver Bailey notifications@github.com wrote:

The spec sheet is misleading. plus or minus 10% means minus 10% of 5 volts, or 4.5 volts. plus 10% of 24 volts means is should operate at 26.4 volts. You can't subtract 2.4 volts from 5 volts and expect the unit to work. It's a voltage range not an absolute value. I would be cautious to use more than plus or mins .5 volt.

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/bigtreetech/BIGTREETECH-SKR-CR6/issues/9#issuecomment-766921465, or unsubscribe https://github.com/notifications/unsubscribe-auth/AGYAYGTR6T5JE5NQW65YZYLS3WI7HANCNFSM4WCYYBYQ .

IckZ commented 3 years ago

Hello! To be on the safe side I've put the power line of the sensor to the 5V output of the free "RGB" connection on the board. Now the red LED light up and everything seems to be fine. During my tests I've recognized that there are also only 3.3V on the EXP3 Connection. Can anyone of you confirm this?