LitePlacer.com forums

I've created some PCBs in Eagle and BOM's for the Vacuum Sensing board referenced in this post:

viewtopic.php?f=13&t=308&hilit=vacuum+sensing&start=40

and this website:

https://makr.zone/vacuum-sensor/192/

License is the same as _Markk's for this project as it's an extension of his great work.

The board files can be uploaded to OSHPark directly if you don't have Eagle, I've included BOM's. It includes holes for mounting (M3's) and for a small cable tie to attach the tube to the sensor. Board is also millable on an Othermill (which is what I did).

I used these to avoiding having to pull the head apart and realign: https://www.liteplacer.com/shop20/index ... duct_id=61

Hi, Jet. I have read some of your posts with a lot of interest. Regarding the vacuum sensor board, are you using the "stock" vacuum pump and solenoid as supplied by Juha? I saw that you apply the vacuum for 2.5 seconds. Is that to allow the adc reading to settle? I also saw in a separate post that you modified the firmware for the tinyg to enable $$adc0. Is this firmware is needed to use the vacuum sensor?

freeman wrote:Regarding the vacuum sensor board, are you using the "stock" vacuum pump and solenoid as supplied by Juha?

Yes, and just made the the length of tubing to the nozzle a bit longer so I could route the piping over the sensor, then
melted a hole in the pipe for the sensor as per the referenced post.

freeman wrote: I saw that you apply the vacuum for 2.5 seconds. Is that to allow the adc reading to settle?

That may have not been my post, but this is the way I do it now, adc settles very fast, but vacuum will take a while
to increase or decrease, although when the damp valve is activated to release, that’s very fast.

Because you’re in contact with the part when it’s picked, for pickup I increase Z back to 0, then check the vacuum,
this ensures the part is either there or not, and gives time for the vacuum to build.

For detecting placement (part leaving the nozzle after placement) it’s not really feasible with OpenPNP, it would need to be checked before the next pick with some code changes (which are coming). This is partly due to TinyG. However, this isn’t
a big deal in practice.

I find vacuum sensing on pickup very useful. Because you know early on that a part hasn’t been picked up,
it leads to less confusion as prior to that, on 0402’s occasionally they got past the “present on nozzle” check.

And if you have the situation where you have a “leaky” part, for example I have a 0.4mm pitch 30 pin mezzanine connector which doesn’t seal the nozzle completely, then it’s easy to change the vacuum levels for a particular nozzle.

freeman wrote: I also saw in a separate post that you modified the firmware for the tinyg to enable $$adc0. Is this firmware is needed to use the vacuum sensor?

Yes, it is if you’re using TinyG. By default TinyG has no ADC support (although the micro controller has adc support).
But the firmware update is very easy, it updates over USB.

The command is $adc and provides a value between 0 and 4095. Higher values indicate less vacuum. With the suggested pressure sensor, my readings run from about 1200(vacuum) to 4095(no vacuum). My typical on/off values I set at 3900 and 3800.

What are Vacuum Sensing PCBs ?

It enables the nozzle to detect that a part has been pickup by detecting the change in vacuum of a part attached versus not

Where can I find the TinyG firmware with the ADC patch ?

I believe it's in the referenced post