TMC2100 How hot?


Chris Vaughan
 
Edited

I've put together the v1.27 miniPCB with TMC 2100s. I've got CFG1/2/3 at GND/open/open for 16 microstep spreadCycle mode. I'm using polulo 1209 stepper motors (2.7V 1A). Just waiting on some pulleys to put it on an EQ5. All is working well, connecting via bluetooth with the android APP and skysafari.

My question is, how hot should the TMC2100s get ?
They are getting very hot after 10-15min. So hot that I can't touch the heatsink on the TMC2100s for more than a few secs. This was with Vref set to 1V (which I'm sure is what a 1A stepper should be set to on the TMC2100). I dropped Vref to 0.7V and its still hot. This was with it running on a 12V supply, but just got a 12-24V converter and its still hot (with Vref at 0.7 - 1V). The stepper motors get warm but not hot. If I drop Vref too much (e.g. down to 0.5V) then it stalls at any GOTO speed above 1deg/sec.

Is this how it is? Mind you, ambient temp was about 28C at night when I tested it. Sydney was the hottest place on the planet yesterday!!

Cheers Chris


Howard Dutton
 

Seem a bit hotter than I would expect but then the ambient temperature conditions have to be factored in.
Regardless, the device has thermal shutdown at 135 deg. C and I'd say you're not anywhere near that if you can hold onto the heat sinks for a couple of seconds.

Do you use the larger type like these? https://www.ebay.com/itm/10pcs-Stepper-Motor-Driver-Heat-Sink-Cooling-Block-for-TMC2100-8825-Driver-Model/401435289492?hash=item5d77686794:g:I0kAAOSwUn9Z9t~D


Chris Vaughan
 

Yes, they look like the heatsinks that came with the TMC2100s.
The heatsinks are just warm when I park it with the APP.

I've got a temp probe somewhere, maybe I'll measure it.
And I just got some TMC2130s. I might compare them.


Howard Dutton
 

When you park OnStep uses the EN pin to turn off the drivers so that's expected.


Chris Vaughan
 

I suppose the temp is probably OK. A temperature probe right down in the heatsink says its 62C when using a 12V supply and 70C with a 24V supply (both using Vref = 0.75V which seems to be enough to avoid stalling with 4 deg/sec GOTOs).

One more question if anyone can help.
I've just got some TMC 2130s. Can they be used in SPI mode on the miniPCB v1.27 ?
The wiki for the minPCB in (Choice of Stepper) mentions putting jumpers on J5 & J10, but in (SPI Interface) it says SPI not supported. The answer is probably obvious but I can't figure it out.


Howard Dutton
 

The TMC2130 in SPI mode is supported on the MiniPCB (all versions.)

I see what you're talking about in that other section "SPI interface:".  I'm talking about the hardware SPI interface there not the "bit-banged" software interfaces to the stepper drivers.  I'll change that section (or remove it) to make that clear.


JoAnn
 

I also have a question. My 2100 are smoking hot after a few seconds. I did not get any heat sinks with mine, I guess I have to order separate. If using the miniPCB which what I plan on, how do you attach the heatsinks if they go on the underneath. Should I have soldered my drivers where the heatsinks face up? 


JoAnn
 


JoAnn
 

Uhmm, disregard this ridiculous question :) I just bought some of the nice big blue heat sinks and get that they go on the gold top area not directly on the processor. Luckily I found a US seller on eBay. 


Terry Fishlock <telfish@...>
 

Have you adjusted the trim pots to the right reference voltage?

On Tue, Jan 16, 2018 at 10:05 PM, <coachbosswife@...> wrote:
Uhmm, disregard this ridiculous question :) I just bought some of the nice big blue heat sinks and get that they go on the gold top area not directly on the processor. Luckily I found a US seller on eBay. 



JoAnn
 

I have just adjusted them to 1v. TBH I have no idea what they should be set to but at 1v the motors turn and do not stutter. these are my motors https://www.omc-stepperonline.com/hybrid-stepper-motor/nema-17-bipolar-45ncm-64ozin-2a-42x40mm-4wires-w-1m-cable-and-connector-17hs16-2004s1.html. The driver still gets HOT so I am not going to mess too much until I get the heatsinks. 


Howard Dutton
 
Edited


Mark Christensen
 

CoachBossWife (name?),

 

1.       The motors you have chosen are rated at 2Amps, which is the above the RMS max  continuous rating for the TMC2100 (1.25amps RMS, 1.77 peak). In tracking mode you are possibly going to draw this. These are really beefy motors. Why? This choice will also seriously limit your battery life (if that matters).

 

2.       The common references to setting Vref are questionable, see

http://reprap.org/wiki/TMC2100#Setting_the_reference_voltage_.2F_motor_current

 

As I read that web page (found by simply Googling), a 1v Vref will set the current limit at 0.71 amps. But then you should not be seeing much heat at all. I have driven TMC2100 silentStepSticks with 1.68 amp motors and while it gets warm it isn’t bad. I think I set the Vref to under .5V. It’s been a while.

BUT in any case the 1v Vref figure conflicts with the TMC2100 data sheet from TMC, which I would trust more than a general website that probably is cut and pasting from A4998 data.

 

First, according to the TMC2100 data sheet (TMC2100 DATASHEET (Rev. 1.07 / 2017-MAY-15, page 24) there are three options for the pin CFG3 that sets the current limit mode: GND, Vio, or OPEN. Getting the OPEN setting to work is tricky, as that usually requires you condition the IO port to be in the float tri-state condition and power Vio off of the output of a processor port pin. That is not always possible with some processors.

 

What is the difference between the three conditions?

 

GND: An internal (as opposed to the value you are reading on the pot) voltage is used with the sense resistors. With a .132 ohm resistor (0.11external + 0.020 on chip) that means your current should be limited (see page 23 of the TMC spec sheet).

 

Vio: Internal Sense resistors are used and the two external ones must be shorted as this mode requires that BRA and BRB (pins on the chip itself) be grounded. So unless you mod the silentStepStick you can’t use this mode. Vio is usually taken to be the voltage coming from an output port of the processor, not the V+ (5 or 3.3V) supply.

 

OPEN: The pot value for the voltage (that you are setting to 1V) and the external sense resistors (which happen to be 0.11 ohms) are used. Again, OPEN means floated tri-state which may or may not work with any particular processor. And without testing  one I wouldn’t know.

 

 

In summary,

 

If you have grounded the pin (5 on JP1) then you are using the internal (2.5V) value and the pot is ignored.

 

If you have tied the pin to +5 (or to a port set high) then the two sense resistors on the chip must be used AND you must short the other two (R4 and R2).

 

If you are able to float the pin (the OPEN mode) then you can use the pot as you want to.

 

The RMS current when turning (running, page 24) is give by:

 

(Vref/sqrt(2))/.132 when the CFG3/CSN line is OPEN, which should be the case with the 0.11 ohm (R0805/0R11) sense resistors (R4 and R2 on the SilentStepStick schematics).

 

That results in over 5 amps, so effectively you’re running at full current: 2Amps RMS which is not recommended, even with a heat sink, for continuous operation. And is probably not necessary. Plus, as I said above (1) these motors are probably oversized for your application and are more current than appears in the table on page 23 of the spec sheet.

 

This formula is valid for the current adjustment mode and to enter that mode you MUST  set the CFG3 pin (pin 5 of JP1 on the SilentStep Stick) to OPEN (as in open Tristate logic). Again, read the TMC2100 spec sheet, page 23/24, which recommends a 1.5 amp motor or smaller be used.

 

Hope this helps you.

 

Mark Christensen

 

 

 

From: onstep@groups.io [mailto:onstep@groups.io] On Behalf Of coachbosswife@...
Sent: Wednesday, January 17, 2018 11:33 AM
To: onstep@groups.io
Subject: Re: [onstep] TMC2100 How hot?

 

I have just adjusted them to 1v. TBH I have no idea what they should be set to but at 1v the motors turn and do not stutter. these are my motors https://www.omc-stepperonline.com/hybrid-stepper-motor/nema-17-bipolar-45ncm-64ozin-2a-42x40mm-4wires-w-1m-cable-and-connector-17hs16-2004s1.html. The driver still gets HOT so I am not going to mess too much until I get the heatsinks. 


JoAnn
 
Edited

Mark Christensen, Thanks for the reply. Most of which I don't understand :) 
I believe I have the pin CFG3 open as I have not connected it to anything (I am still breadboarding). I really had no idea what I was doing when ordering stuff so those are the motors I got. Is there a way to use these? With the formula (Vref/sqrt(2))/.132 even if I set the pot to .5v it is still over 2 amps. 
I don't understand how I select the sense resistors. 

Name is JoAnn BTW :)


JoAnn
 

Howard, I did read that but I have no knowledge of electronics. I only gathered from the video how to set the pot, not how much. The data sheets are really greek to me at this point. 


Mark Christensen
 

JoAnn,

The sense resistors are in two flavors, the two internal to the chip (the thing on other the overside of the heatpad 'vias' - which is what the little plated through holes are called in the trade) and the two external sense resistors (on the stepStick but external to the chip). By the setting of CFG3 (GND, Vio, or OPEN) you select which is used. To use the pot (the Vref adjustment) to set the current limit (in conjunction with the sense resistors) you use the OPEN configuration and the formula.

It is unfortunate that the manufacturers of the stepSticks provide little how-to data on configuring these. For the older models that used the Avago chips there was more configuration info available. Most of us have had to piece together the configuration from the schematics for the silentStepSticks, while referencing the TMC documents, which I appreciate most normal human beings will regard as being written in Greek. And then, like yourself, breadboard and experiment to verify our understanding. Add to that the confusion of how to achieve the OPEN tri-state condition and it take a while to get it right.

Mark C.
--------------------------------------------

On Wed, 1/17/18, <coachbosswife@...> wrote:

Subject: Re: [onstep] TMC2100 How hot?
To: onstep@groups.io
Date: Wednesday, January 17, 2018, 7:04 PM

[Edited Message
Follows]
Mark Christensen, Thanks
for the reply. Most of which I don't understand :) 
I believe I have the pin CFG3 open as I have not
connected it to anything (I am still breadboarding). I
really had no idea what I was doing when ordering stuff so
those are the motors I got. Is there a way to use these?
With the formula (Vref/sqrt(2))/.132 even if
I set the pot to .5v it is still over 2 amps. 
I don't understand how I select the sense
resistors. 

Name is JoAnn
BTW :)


Howard Dutton
 
Edited

On Wed, Jan 17, 2018 at 02:42 pm, Mark Christensen wrote:
1.       The motors you have chosen are rated at 2Amps, which is the above the RMS max  continuous rating for the TMC2100 (1.25amps RMS, 1.77 peak). In tracking mode you are possibly going to draw this. These are really beefy motors. Why? This choice will also seriously limit your battery life (if that matters).
The current rating is based on a voltage of 2.2V.  Power, the ability to do work, what heats the stepper motor, what creates the magnetic field is P=IV.  That is power = current * voltage.

All NEMA17 stepper motors with similar body length fall roughly in that power range regardless of the current rating.  There's two coils driven but micro-stepping drivers come in at 0.7 times (RMS) and you end up with a better approximation... 2+2=4... 4*0.7=2.8A...  2.8A*2.2V = 6.2 watts.  If the voltage goes up, to say 12V the current has to drop otherwise you're melting your stepper motor.  So wattage stays the same 6.2, voltage is known at 12, and current is 0.52A (and that's for BOTH coils the stepper driver spec. is per coil.As you can see that number is well within what the stepper driver can handle.  Really the stepper driver isn't going to get into trouble with any NEMA17 stepper motor, they just don't come close to it's power delivery capacity.
[I might be wrong about this so I'm retracting that in suspicion that the stepper driver Vref is like a power measurement?) Regardless, the SSS TMC2100 Vref setting method in the RepRapWiki has worked well during my limited testing.]


Howard Dutton
 

On Wed, Jan 17, 2018 at 02:42 pm, Mark Christensen wrote:

GND: An internal (as opposed to the value you are reading on the pot) voltage is used with the sense resistors. With a .132 ohm resistor (0.11external + 0.020 on chip) that means your current should be limited (see page 23 of the TMC spec sheet).

 

Vio: Internal Sense resistors are used and the two external ones must be shorted as this mode requires that BRA and BRB (pins on the chip itself) be grounded. So unless you mod the silentStepStick you can’t use this mode. Vio is usually taken to be the voltage coming from an output port of the processor, not the V+ (5 or 3.3V) supply.

 

OPEN: The pot value for the voltage (that you are setting to 1V) and the external sense resistors (which happen to be 0.11 ohms) are used. Again, OPEN means floated tri-state which may or may not work with any particular processor. And without testing  one I wouldn’t know.

The CFG3 on the TMC2100 is always OPEN on a SSS TMC2100 (Watterott OEM.)  It has an open solder bridge that accomplishes this regardless of what is done to the CFG3 pin on the carrier.


JoAnn
 

On Wed, Jan 17, 2018 at 02:42 pm, Mark Christensen wrote:

GND: An internal (as opposed to the value you are reading on the pot) voltage is used with the sense resistors. With a .132 ohm resistor (0.11external + 0.020 on chip) that means your current should be limited (see page 23 of the TMC spec sheet).

 

Vio: Internal Sense resistors are used and the two external ones must be shorted as this mode requires that BRA and BRB (pins on the chip itself) be grounded. So unless you mod the silentStepStick you can’t use this mode. Vio is usually taken to be the voltage coming from an output port of the processor, not the V+ (5 or 3.3V) supply.

 

OPEN: The pot value for the voltage (that you are setting to 1V) and the external sense resistors (which happen to be 0.11 ohms) are used. Again, OPEN means floated tri-state which may or may not work with any particular processor. And without testing  one I wouldn’t know.

The CFG3 on the TMC2100 is always OPEN on a SSS TMC2100 (Watterott OEM.)  It has an open solder bridge that accomplishes this regardless of what is done to the CFG3 pin on the carrier.
OK, So I dialed down the pot to .22 roughly and that gives me 1.18 amp roughly. No heat issues at all even w/out heat sinks. Motors are turning fine though they are not under any torque. Is this OK? Is there a way to test them for torque if they are not physically connected to anything? I could get 2 new motors but rather not spend another $25. Also, note that I ma using this for a power supply: 

LE Power Adapter, Transformers, Power Supply For LED Strip, Output 12V DC, 3A Max, 36 Watt Max, UL Listed



Howard Dutton
 

On Wed, Jan 17, 2018 at 02:42 pm, Mark Christensen wrote:
This formula is valid for the current adjustment mode and to enter that mode you MUST  set the CFG3 pin (pin 5 of JP1 on the SilentStep Stick) to OPEN (as in open Tristate logic). Again, read the TMC2100 spec sheet, page 23/24, which recommends a 1.5 amp motor or smaller be used.
I don't think the datasheet is saying 1.5A stepper motors are the limit there:  "The following  table  shows  the  RMS  current  values  which  can be  reached  using  standard  resistors  and motor types fitting without additional motor current scaling."

At the bottom of the table it mentions using AIN current scaling (the pot we adjust does this) for those examples that were out of spec.