Laser Filament Monitor 'SW' PCB Pads

SnowCrash · 24 Jan 2019, 23:43

Hi,

I got Duet's newly released laser filament monitor a while back but only now starting to look into hooking it up in my rig & I have the following questions which I'm hoping to get some info on:

(1) on the sensor's PCB there are a couple of round pads marked 'SW'. Looking at the schematics they seem to me to be intended for connecting an external reset switch - is this correct? and if so, has anyone utilized this feature? How useful is it to have?

(2) What would be the best background color (if any) for the inner chamber where the sensor's 'camera' chip is located (i.e. where the filament runs and inspected by the chip)? does the color even make a difference in this context?

Many thanks in advance.
SnowCrash

dc42 · 24 Jan 2019, 23:50

It's for an optional filament presence switch.
It must be printed in black.

SnowCrash · 24 Jan 2019, 23:56

@dc42 said in Laser Filament Monitor 'SW' PCB Pads & Inner Chamber Color:

It's for an optional filament presence switch.

Thanks for the very quick response, @dc42!

Could you please elaborate on what 'an optional filament presence switch' is and what it does?

dc42 · 25 Jan 2019, 10:30

A filament presence switch is a simple switch that tells the sensor whether filament is present or not. So it can tell the Duet instantly when a spool runs out. But it's not really needed, because the end of the filament will pass through the filament monitor, which should detect loss of motion before the end reaches the extruder drive.

SnowCrash · 25 Jan 2019, 23:17

@dc42 said in Laser Filament Monitor 'SW' PCB Pads & Inner Chamber Color:

A filament presence switch is a simple switch that tells the sensor whether filament is present or not. So it can tell the Duet instantly when a spool runs out. But it's not really needed, because the end of the filament will pass through the filament monitor, which should detect loss of motion before the end reaches the extruder drive.

So the voltage across these pads alternates between High & Low on the basis of filament presence regardless of the main signal from the monitor module? does this functionality exist out-of-the-box or are tweaks needed?

dc42 · 26 Jan 2019, 07:06

You need to change the filament monitor type in the M591 command to enable the filament presence switch.

SnowCrash · 23 Feb 2019, 23:21

I had another look at the schematics for the filament sensor and I'd like to know if I got this straight (it seems like my previous understanding of the SW pads' function wasn't right):

If I bridge the SW 'jumper-pads' (J1) - then the Signal Output (i.e. OUT on P1) becomes a binary output, that is, High for 'no filament' & Low for 'filament present' (or, perhaps, vice versa)?

Also, what is the purpose of the M2 pads (according to the schematics they bridge PA0 & PA1 on the ATtiny)?

Thanks.

dc42 · 24 Feb 2019, 10:23

@snowcrash said in Laser Filament Monitor 'SW' PCB Pads - Unsolved:

If I bridge the SW 'jumper-pads' (J1) - then the Signal Output (i.e. OUT on P1) becomes a binary output, that is, High for 'no filament' & Low for 'filament present' (or, perhaps, vice versa)?

No. One of the 16 bits in the position report returned to the Duet is the switch status.

Also, what is the purpose of the M2 pads (according to the schematics they bridge PA0 & PA1 on the ATtiny)?

To make it easier for us (or anyone else) to prototype new functionality.

SnowCrash · 24 Feb 2019, 12:53

@dc42 said in Laser Filament Monitor 'SW' PCB Pads - Unsolved:

@snowcrash said in Laser Filament Monitor 'SW' PCB Pads - Unsolved:

If I bridge the SW 'jumper-pads' (J1) - then the Signal Output (i.e. OUT on P1) becomes a binary output, that is, High for 'no filament' & Low for 'filament present' (or, perhaps, vice versa)?

No. One of the 16 bits in the position report returned to the Duet is the switch status.

Ok, so... was my original understanding correct? that is, the voltage reading between the 2 pads (High/Low) serves as an indicator for filament present/not-present?

Also, what is the purpose of the M2 pads (according to the schematics they bridge PA0 & PA1 on the ATtiny)?

To make it easier for us (or anyone else) to prototype new functionality.

In what why exactly? could you please give an example?

dc42 · 24 Feb 2019, 17:17

@snowcrash said in Laser Filament Monitor 'SW' PCB Pads - Unsolved:

Ok, so... was my original understanding correct? that is, the voltage reading between the 2 pads (High/Low) serves as an indicator for filament present/not-present?

Our intention is that if you want to add a filament presence switch, you add a switch that shorts those 2 pads together when filament is present.

To make it easier for us (or anyone else) to prototype new functionality.

In what why exactly? could you please give an example?

No, because we haven't used them yet.

SnowCrash · 25 Feb 2019, 01:53

@dc42 said in Laser Filament Monitor 'SW' PCB Pads - Unsolved:

@snowcrash said in Laser Filament Monitor 'SW' PCB Pads - Unsolved:

Ok, so... was my original understanding correct? that is, the voltage reading between the 2 pads (High/Low) serves as an indicator for filament present/not-present?

Our intention is that if you want to add a filament presence switch, you add a switch that shorts those 2 pads together when filament is present.

To make it easier for us (or anyone else) to prototype new functionality.

In what why exactly? could you please give an example?

No, because we haven't used them yet.

Ok, thanks