orcinus wrote:Re: the whole E-stop business...
I have an idea for a fool-proof emergency stop, but it would probably require too many changes to the layout and BOM.
The idea being to add a watchdog IC....
Zat German wrote:... if a finger or arm is being pinched or held against a burning hot element(which is the most injurious situation I can think of at the moment) and you need to get it out with an e-stop, anything still driving the steppers for any amount of time after e-stop is pressed is working against that.
Zat German wrote:I think it is enough to have the ability to drive the CPU RESET low and stepper driver ENABLE low(I think this is the right one to stop the driver from holding the steppers anymore, I am not certain what this "and set the translator to the Home" state means in the datasheet though) and anything more complicated can be implemented by the end user.
frob wrote:Why not just cut the power to the board instead?
What is the benefit to doing it this way?
Zat German wrote:Well, it is not so much a benefit but providing an alternative to just cutting the power in an emergency. I have assumed from all the features of this prototype board and the things you have said about it that it was something to explore possibilities but everything on it may not be on the final version.
Zat German wrote:Having these two lines exposed in an easy to drive way allows us to explore the concept more, especially for one as undeveloped in the 3D printer space as that of an emergency stop. If I have misunderstood the point of the prototype, then yeah, cutting the power is sufficient.
Zat German wrote:edit: Oh yeah, cutting power in an emergency also assumes that you will not be receiving any power from the USB connection.
frob wrote:A watchdog is always a great idea... Assuming you code for it correctly in the micro. but that's easy to do, even though you rarely see it in practice.
frob wrote:Oh, did i forget to mention there's already a watchdog on the board? musta slipped my mind. oh yeah there is, but you'll never find it without a hint.
Hmm that could be a fun "where's Waldo?" challenge for a nice reward. Spot the watchdog and win a prize.
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