[turmite]

Ok I am now trying to get the switches to work with Mach. I am using an Ethernet Smooth Stepper and the Campbell break out board. I have the output from the x axis a side attached to the signal pin on the bob, and a ground wire from supply ground. The bob red axis led glows but not a full brightness. When triggering the x axis switch with the magnet and watching the leds toggle, and the bob axis led get brighter, I know the signal is getting through. Mach however does not indicate a limit has been activated whether I have the input active lo or high......makes no difference. It is like the bob sees it but Mach does not.

Does anyone know if the smooth stepper allows the signals from the limits/home back through to Mach? BTW, I just now thought of this and am curious if I have this wrong. I have pin 11 set for + - and home on the x axis. Is that correct?

Mike

[Falcon69]

I've had a few request for 8 limit switches, instead of the 7 in the kit. I've redesigned the boards now to fit the larger ULN2803 chips which provide the necessary circuits for 8 switches. I've also added a circuit on the external mount that will blink a red LED whenever a limit switch is triggered, kinda like how your network plug port blinks when data is incoming/outgoing. I know, it's not really needed, but it's a cool little added effect.

I need to send away to have a couple boards made as a prototype to make sure I've placed all the traces correctly and it is working as it should. Unfortunately, because of the enlarged chips, I've had to make the mainboard about 7mm in width larger then I had before. Still, it's about 3rd the size of the original old boards.

(thanks for help again John)

[turmite]

hmmmm..........has anyone been able to get Mach3 to recognize when the switch is activated with the magnet?

What I discovered is this set up using Jasons switches is trickling just enough voltage to dimly lite the led on my bob. I called the board manu and he said the led should not be lit unless the switch is tripped. I told him it had a glow that might be 40% of normal lighted condition and when the switch is made the led will go to full brightness but Mach does not see it.

Anyone?

Mike

[daniellyall]

it might need a diode between switch and bob as a g540 does but a MB-02 Break out board
does not, other boards may need one

[Falcon69]

Mike, You may need to put a 5.1 or 5.6 zener diode between the BOB and the wire that goes to the switch outputs of the mainboard. That was the problem that the gecko G540 was having. I included those with the kit. you should have them.

[turmite]

Tried the zener diode. This time there is no led glow on the bob. The switch is still working because the two leds indicate the condition when the magnet is applied.

I have a digitizing probe that I hooked to the signal and ground on the bob and it breaks the circuit, the bob red indicator led lights and Mach sees it and gives the alert! I checked the pin out for the x axis a side to ground an got 0.00vdc. I checked the bob signal pin to ground and initially got over 9 volts which eventually dropped to slightly less than 5. I thought it was just supposed to have 5 vdc so I disconnected the main board connections and took the reading again. It still read the same and did the same high to low!

Any answers.

I intend to machine 4 small digitizer bodies and circuit boards this afternoon and just use those until I can come up with a solution with the mag switches. I have to get started producing parts again or I will be living in the shop!

Mike

[Falcon69]

Mike, I'd like to try something.

Could you goto your neighborhood Radioshack and pick up a PNP transistor?

Wire the base to the limitswitch output on the mainboard, the collector to ground, and the emitter to the BoB output/input?

See if that works. The transistor should switch on when the Switches voltage drops to the low end of the volts (around .20 volts). This will send the base of the transistor low, and turn it on allowing the circuit to flow from emitter to collector. You may need to put a 10k resistor between the switch output and the transistor. When the transistor opens, it should allow the output of the BoB to ground out, as it should be doing. If that works, I may make a series of transistors on the new board that can be jumper selectable, so we can avoid this problem in the future.

Let me know what you find.

If it works, I will send You a new board kit, when I get them finished.

[turmite]

Jason thank you for the great customer service. Thanks for the ph call this afternoon as well. I did not have time to get to RS this afternoon because by the time I got your call, finished up at the shop, I looked at my clock and it was past closing time for the local RS. I will run to big town tomorrow and pick up the transistor and see if that fixes it. I hope so. BTW thank you for the offer of the new kit!

Mike

[turmite]

Jason just completed the test, and it is still not working. I followed your instructions, as well as paying close attention to the orientation of the transistor legs. I got good solder joints with minimal heat. I tapped into the ground wire that I had placed from the input ground on the main board, I tied the base to the axis output on the main board, and tied the emitter to the bob in/out. Bob led, glows slightly, and once the switch is triggered the led gets bright, returning to the glow when the magnet is moved away. Still no recognition in Mach. Now here is where it gets weird. I remove power to the main board, take the ground wire off and Mach indicates a limit has been made. I can reset Mach, touch the ground to the input ground and again, it trips. Turn power back on and nothing!

I wonder if I have the emitter and base reversed. The package says the following. Shown with heat sink down. 123 from left to right, base, collector, emitter.
Heat sink down would mean as I am soldering the heat sink would be down and away from me......right?


Mike

[Falcon69]

oh, i have no idea. I'd have to look at it and the package. Been awhile since I have used those through hole transistors.

I've been told that the new boards that utilize three ULN2803 chips solve that problem you are having. So, See if you can wire up using basic switches for now, and when I get a few of these kits finished, I will send you one. It will be a couple months till I have them ready, in the mean time, We'll see if we can get your current board working. John has some ideas on that.

[turmite]

Jason would it help if I sent you my spare Campbell Designs board? I am not going to install it for a little while. If you need it, pm my your address.

Mike

[daniellyall]

try using switches connected directly to you bob that way if they work its the board that's shagged

[Falcon69]

The switches he has Daniallyall, are only set-up to work with the Mainboard and connaot operate with the BoB on their own.

[john-100]

Hi Mike

sorry for the delay Ive had a few PC problems

now I've had a look at the Campbell BOB http://campbelldesigns.net/files/bre...-guide-1-8.pdf

the BOBs opto isolator input is powered from a 12v supply and the switch from a 5v supply
, its possible for enough current to flow for the BOB not to see the switch as open

the two transistor buffer with an open collector output should solve the problem -

which version of the switches do you have
the ones with the 1/8" jack plugs or the 5 pin mini USB ?


John

Attachment 189954

[Falcon69]

He has the 5pin USB version

[john-100]

Hi Mike
I've another diagram of the buffer / level translator

having another look at the 5 wire limit switch
I can see how a cable fault that short circuits the +5V wire to a wire connectied to one of limit switches LED's
will damage a ULN2003

this short circuit will connect +5V to an ULN2003 output pin
and result in the NPN transistor inside of the ULN2003 short circuiting the +5V supply to ground when it switches on



a possible fix would be adding a 100 ohm resistor into the wiring between each ULN2003 output pin and the USB socket

to avoid any mods to the PCB
the 14 wires in the 40 way ribbon cable could be cut and the resistors added
with heat shrink sleeving covering the joints and 100 ohm resistors

John


Attachment 190316

[Falcon69]

Thank You John. I will make that adjustment on the new boards. But, I think I will put the 100ohm resistors on the switch itself, there is room now, that I have taken the jacks off them for casting in resin. Would it be safe to do the same thing to the single switch? the one with the transistor on the switch itself? Connect the 100ohm resistor to each of the Red and Greed LED's cathodes?

[john-100]

Hi Jason

the 100 ohm resistors need to be on the main board so they are between the USB socket and the ULN2003 output
moving them to the limit switch would be like changing the existing 100 and 150 ohm resistor to 200 and 250 ohms

the only other thing to protect is the SS441 - not easy to do and keep the component count low

on the limit switch with one LED and the 3 terminal jack socket
the HALL swich has to sink the current for the led
plus the extra current from the circuit its connected - printer port , BOB etc

the resistor would need to limit the current to a few mA if the signal wire was shorted to +5V
a 2500 ohm resistor would limit the current to 2 mA
but the switch would then only switch a high input impedance circuit or CMOS logic IC
and is likely to pickup noise

with the 2 LED version , a 270 ohm resistor could connect the SS441 output to the USB connector
with the output wire shorted to +5V the SS441 would sink 18mA (5/270 = 18 mA )
plus the 2mA through the 2K2 pullup resistor on the switch PCB ( 5/2200 = 2.3mA )
the SS441 can only sink a maximum continuous current of 20 mA

if the switch output is connected to a TTL logic chip input the 0.4V dropped across the 270 ohm resistor could be a problem
added to the volt drop across the diode array on the two ULN2003 board
1V is higher than a TTL logic 0

I expect the the latest board will work with the addition of the 270 ohm resistor to the switch output

the input current to switch on the first ULN2003 transistor is limited by the 2K2 pullup resistor and the 2K7 resistor inside the IC
the extra 270 ohms is only about a 5% increase

as the extra IC provides buffered open collector outputs
the prevoius issues with the 12V inputs of the Gecko G540 or the Campbell B.O.B should be solved

John

[Falcon69]

Thought I would post up here instead of sending a private message.

Mike, aka Turmite, was kind enough to send me his brand new BoB, Campbell Designs Combo Revision 5. A rather nice board, but if it had utilized surface mount technology instead of through hole design, it could be about 1/3rd it's size.

This board has a 12 volt output for the limit/home switches that operate using an opto-isolator. Similar to that of the G540 Gecko BoB/Drive.

I have just tested it using the new boards which utilize 3x ULN2803 chipset. No diodes, no zener diodes, just a straight connection to the switches and the ground wires grounded out at the same point of the ground input of the limit switch board.

IT WORKS! And it works pretty well I might say.

All Limit switches function separate of each other, meaning, only their LED's light up when triggered. Same goes for the panel mount LED's. The test lamp switch turns on all the panel LED lights without affecting the BoB functions.

It took me awhile to figure out mach3 and the ethernet smoothstepper. It seems that the original mach2 file I had (a pirated copy I got when I bought a cheap China Board from eBay) had the same file folder name that the new mach3 downloaded it to, causing major problems with the connectivity using the smoothstepper.

Lesson learned here, always remove old programs from the computer before installing new ones.

Thank You Mike. I will be busy tomorrow working for Habitat for Humanity Volunteering, so I wont get a chance to make it to the Post Office, but I will ship it out first thing Monday when I get a chance.

I really appreciate you trusting me enough to ship me your $245 BoB to test Mike. When I get these new boards finished (which will be a couple months), I will send you out the new kit. This is a much better kit, both in looks, functionality, and size.

Again, Thank You Mike for your patience, and John100, Thanks a bunch for your help and knowledge of these switches, and of course Romanlini for your idea to do this in the first place!

Now that I know the new boards work without a problem, both with an Opto-Isolated/Non-Opto-Isolated and 12volt/5volt switch output from BoB, I feel good about producing these now and getting them ready to ship.

(I am so glad I built that Reflow Oven!)

Jason

EDIT: Oh, also wanted to say. I got the molds done yesterday for the casting of the limit switches. I will cast a generic board (it won't have components on it, but I might stick some on their just to give it a look) so you all can see how they will look with a clear resin over the top (and under them). It's actually kinda cool, I did some before, and the LED's can't even be seen, except for the actual diode circuit. These new little limit switches have screw mounts already on them, clear resin casting, a 6 inch wire lead to a quick disconnect board (either a mini-usb port, or a simple board to solder wires to for hardwiring), as well as a 1mm thick casting on the bottom so you won't need to use washers to lift them up off the surface to protect the traces up underneath the board.

[hollisin]

Sir,
I have been trying to follow this thread since the beginning and am having a difficult time. I have purchased the components and have a circuit working like the one that's pictured on page 77 of this thread that's way back Near the beginning. It seems the current proposed circuits are much more complicated some even having remote LEDs from the sensor. Is it possible for someone to post a summary of the direction and progress so far. I am just looking for a simple 5v switch with a LED to indicate activity.
Thanks
Jack