Quick question about boot order with an RPi and Duet 3

deckingman · 24 Apr 2020, 15:44

@Danal Yes, the Mosquito heat breaks have extremely low thermal mass. The cross sectional area is in the order of 15% of say an E3D V6 where the heat break is also a structural element. Which makes them extremely efficient as heat breaks and as I mentioned above, one can print PLA all day long with no fan and even without the tiny copper heat sink providing the filament is constantly moving forward (albeit slowly). The problem arises when the filament is static because heat will creep up through the filament itself even though the thermal transfer via the thin wall stainless steel tubes is minimal. That's when the fan is needed.

By way of comparison, here is picture of my 6 input hot end assembly on the right next to a Diamond 5 colour on the left. The heat breaks/heat sinks on the Diamond are modified V6 lite (the big finned sliver bits) and the heat break assemblies on mine are the small copper parts which you can just make out if you peer closely.

Ref the fan(s) - I think I'll just wire them as always on as I described above. I destroyed the originals by feeding them 24V but replacements are on the way, and they are almost silent (to my aged ears). Even the high flow versions that I'm currently using aren't too bad.

A Former User · 24 Apr 2020, 15:47

Did you comment on where the fan(s) are connected? Curious if this is different for the toolboard vs the expansion and main board.

deckingman · 24 Apr 2020, 15:51

@bearer said in Quick question about boot order with an RPi and Duet 3:

Did you comment on where the fan(s) are connected? Curious if this is different for the toolboard vs the expansion and main board.

I didn't - but they are (currently) just connected to ~~io6~~ OUT6 on one of the expansion boards (I think it's 6 - the first 2 pin header).

Edit - I meant out6 not io6 - just corrected

A Former User · 24 Apr 2020, 15:53

@deckingman said in Quick question about boot order with an RPi and Duet 3:

@bearer said in Quick question about boot order with an RPi and Duet 3:

Did you comment on where the fan(s) are connected? Curious if this is different for the toolboard vs the expansion and main board.

I didn't - but they are (currently) just connected to io6 on one of the expansion boards (I think it's 6 - the first 2 pin header).

Thanks, if you have a toolboard I'd love to see if its different. (both expansion and main board have the pull downs (on all outputs), while the tool board does not). Just a curiosity on my end, so don't put much effort in it on my behalf.

deckingman · 24 Apr 2020, 15:54

@bearer said in Quick question about boot order with an RPi and Duet 3:

@deckingman said in Quick question about boot order with an RPi and Duet 3:

@bearer said in Quick question about boot order with an RPi and Duet 3:

Did you comment on where the fan(s) are connected? Curious if this is different for the toolboard vs the expansion and main board.

I didn't - but they are (currently) just connected to io6 on one of the expansion boards (I think it's 6 - the first 2 pin header).

Thanks, if you have a toolboard I'd love to see if its different. (both expansion and main board have the pull downs, while the tool board does not). Just a curiosity on my end, so don't put much effort in it on my behalf.

Sorry - don't have any tool boards. Also see my edited post above (OUT6 not io6).

A Former User · 24 Apr 2020, 15:56

fair enough! which out it is makes little difference, they're driven the same way all of them.

maybe some of the other users who do have a toolboard can chime in if the behavior is the same as it would be interesting to factor in when people ask if they should get this or that.

deckingman · 24 Apr 2020, 16:06

@bearer The only reason I used OUT6 is that these are simple 2 wire fans and the lower numbered OUT headers are 4 pin with additional gnd and tacho. So I wanted to keep these headers in reserve in case I ever need to add a tacho fan.

A Former User · 24 Apr 2020, 16:08

I meant that which output is used doesn't matter with respect to the behavior when the board is reset. There are indeed other considerations to make.

Phaedrux · 24 Apr 2020, 17:10

Have not tried this myself, but there are examples of people getting the Pi to boot in ~5 seconds with some modifications.

http://himeshp.blogspot.com/2018/08/fast-boot-with-raspberry-pi.html

Note that was with Pi3 a couple years ago now. Not sure how relevant it would be to Pi4.

The pi forums have many threads on trying to optimize boot time. https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=258091

Normal SD card boot times are all pretty close to 25 seconds on the pi4 from what I've seen. Moving to an SSD may improve that a bit but I don't think that's a natively supported option yet.

https://www.youtube.com/watch?v=gp6XW-fGVjo

If sticking with an SD card, try and choose one with high write speeds and high IOPs. A2 U3 class.

chrishamm · 24 Apr 2020, 17:12

I just looked into the boot process again and I've found a way to prioritise DSF. This way, DCS will start within 10 seconds when the Pi is powered on.

deckingman · 24 Apr 2020, 18:07

On the subject or wiring the fans as being always on, looking at the wiring diagram https://d17kynu4zpq5hy.cloudfront.net/igi/duet3d/6mYpDS1EmhXHobw4.huge it looks like I could simply connect the fans to OUT3 (or 4 or 5) GND and V_OUTLC1.

gtj0 · 24 Apr 2020, 18:09

@deckingman said in Quick question about boot order with an RPi and Duet 3:

On the subject or wiring the fans as being always on, looking at the wiring diagram https://d17kynu4zpq5hy.cloudfront.net/igi/duet3d/6mYpDS1EmhXHobw4.huge it looks like I could simply connect the fans to OUT3 (or 4 or 5) GND and V_OUTLC1.

I may have missed this before but why not use the always-on fan header right above out_0?

A Former User · 24 Apr 2020, 18:24

@deckingman said in Quick question about boot order with an RPi and Duet 3:

V_OUTLC1.

if you remove the jumper that pin has no voltage, use 12v on same header instead.

A Former User · 24 Apr 2020, 18:25

@gtj0 said in Quick question about boot order with an RPi and Duet 3:

I may have missed this before but why not use the always-on fan header right above out_0?

methinks he has 24v Vin and 12v fans.

deckingman · 24 Apr 2020, 20:20

@bearer said in Quick question about boot order with an RPi and Duet 3:

@deckingman said in Quick question about boot order with an RPi and Duet 3:

V_OUTLC1.

if you remove the jumper that pin has no voltage, use 12v on same header instead.

???? There is no 12V on that header - but I'm not going to remove the jumper - I'll set it to 12V.

deckingman · 24 Apr 2020, 20:22

@bearer said in Quick question about boot order with an RPi and Duet 3:

@gtj0 said in Quick question about boot order with an RPi and Duet 3:

I may have missed this before but why not use the always-on fan header right above out_0?

methinks he has 24v Vin and 12v fans.

Correct.

A Former User · 24 Apr 2020, 20:24

@deckingman said in Quick question about boot order with an RPi and Duet 3:

???? There is no 12V on that header - but I'm not going to remove the jumper - I'll set it to 12V.

never mind, i thought you meant to use the pin on the voltage selection header, but that doesn't make sense.

you're good to go as planned

deckingman · 24 Apr 2020, 20:27

@bearer said in Quick question about boot order with an RPi and Duet 3:

@deckingman said in Quick question about boot order with an RPi and Duet 3:

???? There is no 12V on that header - but I'm not going to remove the jumper - I'll set it to 12V.

never mind, i thought you meant to use the pin on the voltage selection header, but that doesn't make sense.

you're good to go as planned

You had me worried there - at my age, senile dementia is just around the corner so....

A Former User · 24 Apr 2020, 20:40

@deckingman said in Quick question about boot order with an RPi and Duet 3:

You had me worried there - at my age, senile dementia is just around the corner so....

seems i'm the one ought be worried