Pages: [1] 2   Go Down
Author Topic: Arduino mega 2560 crystal oscillator  (Read 2254 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 17
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hello

Does anyone know what is the tolerance of the crystal oscillator used in Arduino mega 2560.

Regards
Logged

Left Coast, CA (USA)
Offline Offline
Brattain Member
*****
Karma: 361
Posts: 17263
Measurement changes behavior
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Pet peeve

Quote
it shows the
following part, being a resonator and not a crystal,

There are ceramic resonators and there are crystal resonators, both can be called resonators. And in fact a ceramic resonator could be called a crystal resonator as it's ceramic structure is of a crystalline nature. A quartz crystal resonator also has (of course) a crystalline structure, and is what most people mean when they say, in overly shorthand fashion, 'crystal'.

Been working with crystal resonators sense the 60s where we would sometimes grind the blanks in tooth paste to try and raise it's frequency resonance, or draw with pencil lead to try and lower the frequency. Novice ham operators in the 60s were required to be crystal resonator controlled on their 75 watt maximum morse code transmitters, and not until one upgraded their licence were they free to use a VFO and were therefore no longer 'rock bound'.

Lefty
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 17
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Yes, I assume a resonator is used on the one I am using as I have taken one micro controller  as the ref and measured the skew and its gives me ppm error of upto 1000ppm.

I was trying to study the relation between the applied voltage and crystal skew. But it seems the board has resonator which is not very accurate. How can I solve this problem. My aim was to obtain less than 5ppm error with the arduino without using any external clock.
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 17
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

The crystal has the following marking: SPK16.000G
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 17
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Found out from Arduino that Ceramic Resonators have been used on Arduino Mega 2560 R3.
Logged

Offline Offline
Edison Member
*
Karma: 116
Posts: 2205
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
I was trying to study the relation between the applied voltage and crystal skew.

What voltage?

Quote
But it seems the board has resonator which is not very accurate.

A brain-dead decision.

Quote
How can I solve this problem.

You can replace it with a crystal oscillator or an external clock.

Quote
My aim was to obtain less than 5ppm error with the arduino

Very easy to do.

Quote
without using any external clock.

That can be challenging. Crystals guarantted to be in that range are expensive and not very common. A far simpler / cheaper solution is to use external clocks. TCXOs for example are that much more expensive than a crystal.
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 17
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I am doing my research under wireless sensor network and as such the cost and power consumption are very important. Therefore the only option could be replacing the resonators with crystal oscillators. Using a external clock would increase the cost and power consumption of the sensor nodes.
Logged

SG
Offline Offline
God Member
*****
Karma: 11
Posts: 500
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Using a external clock would increase the cost and power consumption of the sensor nodes.

http://www.digikey.com/product-detail/en/FOX924B-16.000/631-1071-1-ND/1024776
Quote
Unit Cost  US$3.76
Current - Supply (Max)   6mA
Cost was not that high and power consumption is low too.
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 17
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Here we are looking at not only 1 node, but many nodes hence when it comes to the fact of deploying many sensor nodes then the cost seems high.

But nice suggestion, definitely it will solve the problem where only few nodes are required.
Logged

SG
Offline Offline
God Member
*****
Karma: 11
Posts: 500
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

But for low cost of US$0.63 Crystal can have lower frequency Stability of ±9ppm only and most have ±30ppm.
http://www.digikey.com/product-detail/en/TSX-3225%2016.0000MF09Z-AC3/SER3628CT-ND/1802879
Logged

Offline Offline
Edison Member
*
Karma: 116
Posts: 2205
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Crystals are actually more expensive than comparable oscillators.
Logged

Cumming, GA
Offline Offline
Edison Member
*
Karma: 20
Posts: 1643
Ultimate DIY: Arduino
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

To me, that's nonsense.

A 16 MHZ MCU compatible crystal is about $0.50 and add a few more cents for the 2 capacitors needed.  (So maybe $1.00 Max) That's still less than $3.50 you would pay for a crystal oscillator package.
Logged

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 525
Posts: 26554
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

50 cents, you're overpaying.
http://www.digikey.com/product-detail/en/ATS16B/CTX1085-ND/2640031
35 cents, with proper software can see as little as 1 second drift per day.

caps, 18 cents if only buying a couple, I usually get more
http://www.digikey.com/product-detail/en/C317C220J2G5TA/399-4220-ND/817996

71 cents.

But I typically get my parts here
http://www.dipmicro.com/store/index.php?act=viewProd&productCode=XC7-16000
28 cents
http://www.dipmicro.com/store/C1K22-50
9 cents
46 cents total in 1-lot, and I usually get more to have parts to play with.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Left Coast, CA (USA)
Offline Offline
Brattain Member
*****
Karma: 361
Posts: 17263
Measurement changes behavior
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

50 cents, you're overpaying.
http://www.digikey.com/product-detail/en/ATS16B/CTX1085-ND/2640031
35 cents, with proper software can see as little as 1 second drift per day.

caps, 18 cents if only buying a couple, I usually get more
http://www.digikey.com/product-detail/en/C317C220J2G5TA/399-4220-ND/817996

71 cents.

But I typically get my parts here
http://www.dipmicro.com/store/index.php?act=viewProd&productCode=XC7-16000
28 cents
http://www.dipmicro.com/store/C1K22-50
9 cents
46 cents total in 1-lot, and I usually get more to have parts to play with.

And of course there are those 10 cent crystals:
http://www.taydaelectronics.com/crystals-resonators-oscilliators/crystals/16-000-mhz-16-mhz-crystal-hc-49-s-low-profile.html

And 1 cent caps (but you must order ten of them minimum, bummer  smiley-wink )

http://www.taydaelectronics.com/capacitors/ceramic-disc-capacitors/10-x-22pf-50v-ceramic-disc-capacitor-pkg-of-10.html

Bought ten of each so should be set for a while now.

Lefty
Logged

Offline Offline
Edison Member
*
Karma: 116
Posts: 2205
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
A 16 MHZ MCU compatible crystal is about $0.50 and add a few more cents for the 2 capacitors needed.

Those are 5ppm crystals?
Logged

Pages: [1] 2   Go Up
Jump to: