Where to buy magnet for AS5040 magnetic rotary sensor?

[Ichan]

I wasted two days on a stupidity, i though i can use common round magnet for this ic - two days struggling why i can not get good reading from it, i even make a fine 3d adjustable jig to do magnet position alignment using a benchtop cnc. Then i just realized that the magnet should be Diametrically Magnetized while the common round magnets are Axially Magnetized, what a dumb.

So where to buy that magnets, in 100 qty? Digikey, Mouser, Farnell do not sell it..

-ichan

[Checksum8]

That sensor looks great. I need to order a couple. I found this site
sells Diametrical Magnets,

https://www.amazingmagnets.com/p-182-r250a1-dm.aspx

[Magnox]

Interesting ic, I've just ordered some samples to play with.

Other suppliers of suitable magnets in smaller quantities are:

http://www.supermagnete.de/eng/S-10-05-DN

http://www.first4magnets.com/diametrically-magnetised-magnets-t177

[Checksum8]

Does anyone know if these come with default configuration? Or do they need to be configured and programmed before using?

Thanks

[Ichan]

The datasheet specify minimum diameter 4mm and min thickness 2mm, suggested size is 6mm dia x 2.5 mm thick, first4magnets.com link above has 6x1mm and 6x4mm but expensive at 1.9 and 2.83 pounds mean about 3 and 4.5 US$ per piece.

AMS website has some link to the magnet source, but seems only for samples and 1k or more order - priced at 1.3 pounds / pcs if i remember correctly.

There must be some source with good price as i buy common (axial) round 6x3mm magnet at about US$ 0.2 / pcs.

Does anyone know if these come with default configuration? Or do they need to be configured and programmed before using?

I've read the datasheet many many times  . For AS5040 mostly programming is not required, the default is quadrature encoder with A, B, and Index signal - the absolute position (10 bit for AS5040) can be read via SPI like communication. Also there is pwm output of absolute position, by filtering the pwm output with RC we can read the absolute position using ADC.

To use it as quadrature encoder connect the PROG pin to VSS and pulldown the CS pin using 4K7 or less resistor.

-ichan

[solutions]

http://www.magnet-shop.com/neodymium-magnets/discmagnets/discmagnet-40-x-40-mm-n35h-nickel-diametral-120c::856.html

[Ichan]

Thanks, this is the best candidate now. The price is right - the diameter is just at the minimum boundary.

-ichan

[Magnox]

I just have to say I'm impressed with the speed of AMS's sample delivery. Fedex has just dropped them off!

That's about 24 hours from ordering to having them in hand.

[Ichan]

Woa... you then will be a step ahead of me, i bet you bought the magnet samples too.

I got the chip from Digikey, they do not stock the related magnet - now i am still waiting some news from china suppliers.

-ichan

[Magnox]

Aye, three chips and magnets. They'll have to be hidden in my 'to be looked at' drawer until I find time for them. It's hard enough staying focussed on the work I'm supposed to be doing as it is, without extra stuff to play with.

Nice that the chips are SSOP package for a change. Maxim make some great stuff, but all the best is in packages I just can't use (or at least can't be bothered with the effort required) as an amateur.

[Ichan]

I ended up purchasing 1000 pcs from china, US$200 including shipping by DHL - good price as always.

But, here is a snip from the supplier today email:

"It is estimated that the magnets can be completed for you within 14 days. But as the China's National Holiday is coming (from Oct.1st to Oct.7), so the magnets can be offered to you before Oct.20! Pls rest assured that we will do our best to send you them without any delay! ^_^"

Whew.. including shipping and customs time i still have to wait about a month!

Yes the chips size quite fine, rather difficult to use it on hand made pcb - i use fabricated one and assembled 30 of them already, as on the picture attached. This things are related with my thread in here.

-ichan

[Checksum8]

Looks like you are moving along. Will follow your other thread.

Just got my samples, including magnets from AMS. I also requested samples for the joystick sensor
AS5013 will report here later. First, I need to mount the chips on carrier pcb.

[Ichan]

As i said on that thread, this wont be quick - i even still have to wait a month only for the magnets  .

I just modify a little the encoder board design so it can be made with single layer pcb, it should be possible to make it by diy method, such as toner transfer, isolation milling, or even laser engraving (+etching).

The gerbers produced imported by Sprint Layout, then the isolation milling / engraving path can be generated easily as picture below. Attached all the files, altium + sprint layout + isolation milling plt & dxf, may it has any use for anyone who want to try this encoder chip.

-ichan

[Checksum8]

Got my circuit wired and testing on the bench. This is a versatile chip. The PWM and quadrature encoder work great. It can even sense z axis movement, which in my case will be used as push button on my rotary control. I have not tried the serial i/o yet.

Very sensitive to any magnet wobble. I am free handing the magnet mounted in a small tube. So the next step is to make a mechanical fixture with centered shaft with bushing.

Thanks for sharing your pcb design. I have problems soldering/reflowing fine pitch parts to home made boards without a solder mask. So I buy the ebay SSOP16 to dip adapters for protos.

[Magnox]

That makes me wonder if these will be good for seismic sensors. Hmm...

[Ichan]

Great to know the news, how is the resolution? 10 bit for 360 degree is about 0.35 degree, does it seems right?

I think the easiest way to mount it is to use a potentiometer housing, here is the photo of how i will do this.

That makes me wonder if these will be good for seismic sensors. Hmm...

That should be interesting, we have quite unstable land in here.. 

-ichan

[Checksum8]

Great to know the news, how is the resolution? 10 bit for 360 degree is about 0.35 degree, does it seems right?

Yes 0.35 degree resolution. I have the filtered pwm output going to a 10bit ADC. To display 0-360 deg. on the LCD, I multiply the ADC result by 0.3515625.  Using a old pot for a tester is probably the way to go.

@Magnox, the joystick chip (as5013) might make a good seismic sensor. Use a hanging magnet  as pendulum over the sensor? I think this chip uses normal magnets also

[Ichan]

Now i started to be jealous... 

-ichan

[Ichan]

DHL knocking my door today, and 1000 pcs of that kind of magnets in my hand now... woohoo...

Will play with them soon.

-ichan

[Magnox]

Now I'm the one who's jealous... although I did pick up some huge NdFeB magnets really cheap from ebay the other day.

[Ichan]

  Seems you are moving on with the seismic sensor idea.

I just playing with the magnets, real playing no electronics yet. See the picture below, not like their cousins at the back/bottom this magnets are very attractive - my 4 yo son took more than a half of them and do not want to give it back to me  .

I bought it from Dailymag, and the very helpful sales is Crystal Chen - just sharing, no other intention.

-ichan

[solutions]

Tell him to leave them on daddy's laptop computer when he's done playing with them....

[Magnox]

LOL!

Since there are bigger ones in the HD, I doubt it would do any harm. Prove me wrong, I dare you!

Seriously, I get quite nervous about the big N45-rated magnets I have around here. I keep them in a corner of the room, near the ceiling.

I keep them well away from my automatic-winding watches!

Have you seen the motor trick with a bit of wire, an AA cell and a small neodumium magnet?

http://www.youtube.com/watch?v=zKj5AXdEWYg

Mine looked and worked better than that, but I don't do videos.

[Ichan]

Ups... he had his own laptop    Sure not an expensive one (even mine is a cheap one), still i think i better take those magnets asap.

-ichan