I'm all wired up and when I plug in the module the laser turns on. Now I need to see if the output pin shows a change in logic levels. Now I wish I built an indicator led into the module. But I'm off to go ice skating with my family so it will have to wait.
Prolly committing to a laser module size & mounting method is the first step. The laser & sensor need to be butted together. I'll get some of the EG modules.
Oh yeah? You don't think a board for the sensor and passive would be very useful?
I guess I was kind of thinking we'd strap the laser to one side of the PCB or the other.
This latest version has pads on both the top and the bottom of the board which I hope will make it easier to mount the sensor to a laser.
I'm not sure how much it would cost to have 50 made.
The boards from OSH Park generally costs more than some of the other fab houses but OSH Park's prices are very competitive on really small boards (like the one I'm posting here).
This design would cost about $2.40 for three boards. $0.80 per board isn't bad IMO. Update (1/12) The latest version should cost less than $0.70 a board.
Looking at the pictures I just uploaded, I can see I'll want to increase the amount of PCB material around the mounting holes.
There are now five holes on the header. The header has two sections. The section on the left (in the top view) has two holes. This two hole header would connect to the laser. The laser header includes a second Vdd to power the laser. The three hole header could be used to connect to a microcontroller using normal three pin servo connectors. The Vdd pin is in the center like many of Parallax's sensors.
As I said, I didn't like the way the mounting holes were positioned so here's an alternate design.
I included a couple of reference shapes to help indicate the size of the board. The circle is the size of a US quarter. The small square is one square inch. The larger square is 5cm x 5cm. 5cm x 5cm is the size many fab houses use as a standard PCB size. You can have 10 5cm x 5cm boards made for $10.
It looks like six of these small PCBs would fit on a 5cm x 5cm board. You could have over 50 boards made of this small design for about $10. The problem with using the 5cm x 5cm board is the design needs to be panelized so all six boards are connected. Made this way the boards would be about 17 cents each.
@erco, It sounds like you're thinking of a larger PBC to include the laser, right? If so the price per board would increase but I don't think that's much of a concern since, as long as you stay within the 5cm x 5cm size constraint, the board wouldn't cost more than $1 to produce.
I'll wait a bit for feedback before I finish this last small board. I still need to lay many of the traces and I also want to adjust the board outline to make sure it's symmetrical. Once I finish the design, I'll post the gerbers and anyone who wants to can submit the files to OSH Park and have three boards made for about $2.08 (includes shipping in US).
So erco let me know what you have in mind for a larger board and everyone else let me know if you have any suggestions on how to change this latest design. This latest design also allows the passives to be placed on the top or the bottom of the board. The passive can be either surface mount or through hole.
Screenshot attached here. The active side is crystal clear, backside is kinda frosted.
So looking at the clear/active side, the bottom pins are (left to right):
1) Vout (signal out, active low)
2) Ground
3) to laser Cathode
4) +5V
Continuing through the thread, I see I wasn't the only one unsure about this.
So looking at the back of the sensor with the leads pointing down, Vcc (+5V) connects with the pin on the far left.
Besides erco coming right out and telling us, I did find some clues on Philo's website. One of the pictures show the cap connected to the second from the right pin (viewed from the back of the sensor)
Since the cap connects to Vcc and ground, it's pretty clear which pins are which. The cap lead closest to the camera is connected to the sensor's ground pin.
Duane, for my Perf board version I use a three pin servo header (Vout, +5, gnd) and that seems to be enough. It looks like the right side of your board is laid out like that, but the left has another Vcc and cathode which I don't understand.
Update: OK, I think you are allowing the laser leads to be soldered there. I soldered a wire from the Perf board to the housing and directly from the sensors to the cathode.
. . . the left has another Vcc and cathode which I don't understand.
I haven't used either of my sensors yet, but from what I've read, it looks like the sensor controls the laser with the "cathode" pin. Since the ground side of the laser power is supposed to be connected to the sensor, I thought it made sense to add the positive power supply as well.
I think the secret sauce of this sensor is its ability to control the laser. It can compare the brightness level with the laser on and off so it can subtract the background light.
It's much more than just a light meter. I'm starting to understand why erco thinks these are so cool.
In looking at Philo's site he is using a capacitor, across Gnd and Vcc. Is that a decoupling capacitor? I seem to recall seeing another schematic for this circuit that didn't use one.
In looking at Philo's site he is using a capacitor, across Gnd and Vcc. Is that a decoupling capacitor? I seem to recall seeing another schematic for this circuit that didn't use one.
Philo calls it a filtering capacitor. In general, it's a good idea to add a cap to every IC being used. Philo is using a 10uF cap, I think I'd be inclined to use a 0.1uF cap if I weren't being told otherwise by someone with more experience.
I imagine the cap used with the laser sensor helps smooth out the power as the sensor pulses the laser on and off.
I see in the datasheet it says it pulses the laser with a 1/16 duty cycle but I couldn't find what frequency is use. I wonder how fast the laser is being turned on and off?
I see in the datasheet it says it pulses the laser with a 1/16 duty cycle but I couldn't find what frequency is use. I wonder how fast the laser is being turned on and off?
Think I saw something like ~250 hz on my freq meter IIRC.
The good news is that everything is working. The module turns on and if I hold a white card six inches from the sensor the logic transitions from high to low.
The bad news is that my sensor is myopic. As I move the card away the logic transitions quickly to high.
My laser module is right next to the sensor, so it might be the alignment, or maybe the target has to be a reflector?
Update: looking at Philo's module, he has the sensor overlapping the laser module rather than side by side. This looks like he can get even closer alignment because the two are closer to coaxial.
I just submitted (without ordering) the attached gerber files to OSH Park and the price for three boards is $2.00 even. The boards take about two weeks to be delivered after ordering.
I of course haven't tested these boards so I'd suggest anyone ordering a set double check the traces.
@erco, let me know if you have some other layout in mind.
I'll probably wait until tomorrow to order a batch of three boards in case any of you have suggestions on improving the board.
The small 0.05 pitched holes are the same size I used on the encoder sensor PCB designs. I tested the laser sensor leads in the PCBs I had made for the encoder sensors and the leads appear to fit okay in the small holes.
@Duane: you're moving WAY too fast for me. Like I said, the laser module needs to be mounted on board for me, so slow down, partner. Per Martin, this needs to be a standalone unit with a 3-pin header for a servo cable. Numb nuts simple. People will buy.
@Martin: Keep swinging, something's wrong. Did you breadboard? Swap sensors once you double check everything. It's pretty straightforward.
I did not use a breadboard. I only breadboard when I'm building a circuit where no exiting schematic or prototype exists. If someone else blazed that trail I figure the biggest risk is improper wiring which is equally likely on perfboard or breadboard. The risk of defective components is usually so low that I don't worry about it.
Also, people have mentioned the laser lens. My laser module had two lenses, a collimation lens internal to the module head, and an external finer focus lens. I removed the external lens, but left the collimation lens. Did you remove both and allow the beam to spread? That could explain why alignment would be so critical with my rig. I can easily remove that lens if needed.
I stopped by the hardware store and bought some of the 3M reflector tape, so I'll make a target tonight. I think I'm fairly close to getting this working as it seems like an alignment problem.
No laser lens mod at all. You want the tiniest red dot possible. Once I managed to melt the lens while soldering to the brass tube of the laser and messed up the focus. Another dollar wasted!
But I am serious that I always use a socket for the sensor. Machined pins requiredfor a good fit. If you damage the sensor while soldering, you'll never know and you'll drive yourself mad. I tested all the sensors I sold you fine folks and they all worked 100%. Besides avoiding solder/heat damage, a socket lets you easily swap sensors "just in case".
I have machine pins which I'll use if I need to swap the sensor, but I don't think that will be the case. I have a pretty quick touch soldering and rarely heat damage components.
Attaboy Jim! I got approximately the same results (8-10 feet) with my best red reflective tape and my best silver tape, both from the same Ebay seller I listed somewhere previously.
Can't wait to see what you do with yours now that you have it working!
Comments
Prototype first on solderless to verify function! I always use a machined-pin female socket for the sensor; I did mess one up from soldering.
Just as a refresher, you said you did not use a lens on the receiving end? You where able to get 1-2 meter range?
Suddenly we have a horse race! Place your bets, who will get theirs working first, Jim or Martin?
I made a video, but it's not worth putting up.
OK It didn't take long to upload.
I used a standard mirror at about 6".
Now to go to find some reflective material, Home Depot?
It sure seems like this sensor is simple enough to use with just some perf board but if might go ahead and submit at least one design to OSH Park
On with my original post.
Oh yeah? You don't think a board for the sensor and passive would be very useful?
I guess I was kind of thinking we'd strap the laser to one side of the PCB or the other.
This latest version has pads on both the top and the bottom of the board which I hope will make it easier to mount the sensor to a laser.
Do think there's enough demand for 50?
I'm not sure how much it would cost to have 50 made.
The boards from OSH Park generally costs more than some of the other fab houses but OSH Park's prices are very competitive on really small boards (like the one I'm posting here).
This design would cost about $2.40 for three boards. $0.80 per board isn't bad IMO. Update (1/12) The latest version should cost less than $0.70 a board.
Looking at the pictures I just uploaded, I can see I'll want to increase the amount of PCB material around the mounting holes.
There are now five holes on the header. The header has two sections. The section on the left (in the top view) has two holes. This two hole header would connect to the laser. The laser header includes a second Vdd to power the laser. The three hole header could be used to connect to a microcontroller using normal three pin servo connectors. The Vdd pin is in the center like many of Parallax's sensors.
As I said, I didn't like the way the mounting holes were positioned so here's an alternate design.
I included a couple of reference shapes to help indicate the size of the board. The circle is the size of a US quarter. The small square is one square inch. The larger square is 5cm x 5cm. 5cm x 5cm is the size many fab houses use as a standard PCB size. You can have 10 5cm x 5cm boards made for $10.
It looks like six of these small PCBs would fit on a 5cm x 5cm board. You could have over 50 boards made of this small design for about $10. The problem with using the 5cm x 5cm board is the design needs to be panelized so all six boards are connected. Made this way the boards would be about 17 cents each.
@erco, It sounds like you're thinking of a larger PBC to include the laser, right? If so the price per board would increase but I don't think that's much of a concern since, as long as you stay within the 5cm x 5cm size constraint, the board wouldn't cost more than $1 to produce.
I'll wait a bit for feedback before I finish this last small board. I still need to lay many of the traces and I also want to adjust the board outline to make sure it's symmetrical. Once I finish the design, I'll post the gerbers and anyone who wants to can submit the files to OSH Park and have three boards made for about $2.08 (includes shipping in US).
So erco let me know what you have in mind for a larger board and everyone else let me know if you have any suggestions on how to change this latest design. This latest design also allows the passives to be placed on the top or the bottom of the board. The passive can be either surface mount or through hole.
Looking through the thread again, I see erco already answered me.
Continuing through the thread, I see I wasn't the only one unsure about this.
So looking at the back of the sensor with the leads pointing down, Vcc (+5V) connects with the pin on the far left.
Besides erco coming right out and telling us, I did find some clues on Philo's website. One of the pictures show the cap connected to the second from the right pin (viewed from the back of the sensor)
Since the cap connects to Vcc and ground, it's pretty clear which pins are which. The cap lead closest to the camera is connected to the sensor's ground pin.
Update: OK, I think you are allowing the laser leads to be soldered there. I soldered a wire from the Perf board to the housing and directly from the sensors to the cathode.
I haven't used either of my sensors yet, but from what I've read, it looks like the sensor controls the laser with the "cathode" pin. Since the ground side of the laser power is supposed to be connected to the sensor, I thought it made sense to add the positive power supply as well.
I think the secret sauce of this sensor is its ability to control the laser. It can compare the brightness level with the laser on and off so it can subtract the background light.
It's much more than just a light meter. I'm starting to understand why erco thinks these are so cool.
Philo calls it a filtering capacitor. In general, it's a good idea to add a cap to every IC being used. Philo is using a 10uF cap, I think I'd be inclined to use a 0.1uF cap if I weren't being told otherwise by someone with more experience.
I imagine the cap used with the laser sensor helps smooth out the power as the sensor pulses the laser on and off.
I see in the datasheet it says it pulses the laser with a 1/16 duty cycle but I couldn't find what frequency is use. I wonder how fast the laser is being turned on and off?
Finally! I've been blabbing about these sensors and uses for years now. Philo was ahead of his time.
http://forums.parallax.com/showthread.php/143732-Laser-Triangulation-for-Navigation
http://forums.parallax.com/showthread.php/120634-Philo-Phan
Think I saw something like ~250 hz on my freq meter IIRC.
I'm reading 7.58 kHz on my PropScope, 3.71 Volts.
My logic output goes between 0 and 2.63 volts. Could you guys verify that with your rigs?
The good news is that everything is working. The module turns on and if I hold a white card six inches from the sensor the logic transitions from high to low.
The bad news is that my sensor is myopic. As I move the card away the logic transitions quickly to high.
My laser module is right next to the sensor, so it might be the alignment, or maybe the target has to be a reflector?
Update: looking at Philo's module, he has the sensor overlapping the laser module rather than side by side. This looks like he can get even closer alignment because the two are closer to coaxial.
I just submitted (without ordering) the attached gerber files to OSH Park and the price for three boards is $2.00 even. The boards take about two weeks to be delivered after ordering.
I of course haven't tested these boards so I'd suggest anyone ordering a set double check the traces.
@erco, let me know if you have some other layout in mind.
I'll probably wait until tomorrow to order a batch of three boards in case any of you have suggestions on improving the board.
The small 0.05 pitched holes are the same size I used on the encoder sensor PCB designs. I tested the laser sensor leads in the PCBs I had made for the encoder sensors and the leads appear to fit okay in the small holes.
@Martin: Keep swinging, something's wrong. Did you breadboard? Swap sensors once you double check everything. It's pretty straightforward.
Also check this thread. Buzby had a heck of a time getting his to work, and he finally says his particular laser was no good. He claims 26 feet range without lenses with a good laser (I'm skeptical). http://www.picaxeforum.co.uk/showthread.php?24399-Why-no-my-laser-work
I did not use a breadboard. I only breadboard when I'm building a circuit where no exiting schematic or prototype exists. If someone else blazed that trail I figure the biggest risk is improper wiring which is equally likely on perfboard or breadboard. The risk of defective components is usually so low that I don't worry about it.
Also, people have mentioned the laser lens. My laser module had two lenses, a collimation lens internal to the module head, and an external finer focus lens. I removed the external lens, but left the collimation lens. Did you remove both and allow the beam to spread? That could explain why alignment would be so critical with my rig. I can easily remove that lens if needed.
I stopped by the hardware store and bought some of the 3M reflector tape, so I'll make a target tonight. I think I'm fairly close to getting this working as it seems like an alignment problem.
But I am serious that I always use a socket for the sensor. Machined pins required for a good fit. If you damage the sensor while soldering, you'll never know and you'll drive yourself mad. I tested all the sensors I sold you fine folks and they all worked 100%. Besides avoiding solder/heat damage, a socket lets you easily swap sensors "just in case".
I just recently purchased some 0.05" pitch female headers. They look like they might work well with the sensor.
Here's a couple of photos.
You can see in this next photo how the leads make good contact with the metal strips inside the header.
The header also fits in the 0.05" pitched holes I has planned to use on the PCB.
Something to keep in mind for the eventual PCB.
3M reflective tape from Home Depot was cr*p. Gave about 6" of reflective.
Hillman 3" Red Reflector, so-so. About 10', if you move it about.
NAPA Reflective Tape. Best so far. About 8-10'.
Non-front surface mirror, 40' so far. (It's hard to hold it still right after a strong cup of Starbucks Christmas Blend at that range
Can't wait to see what you do with yours now that you have it working!
I have been searching, to no avail, for two days for those auctions.
Anybody recollect the thread?
Here it is, way back in post #21 : http://forums.parallax.com/showthread.php/149770-7-Laser-Sensor-Bulk-Buy?p=1202641&viewfull=1#post1202641
Also see Mike's post at http://forums.parallax.com/showthread.php/149770-7-Laser-Sensor-Bulk-Buy?p=1202668&viewfull=1#post1202668
That's it!
Thanks bro
I'd love too, but the work, that I do to pay the bills, is kicking my butt right now. My boss quit the first of this year……………….