Pages: 1 2 [3] 4   Go Down
Author Topic: resonator vs crystal  (Read 4411 times)
0 Members and 1 Guest are viewing this topic.
UK
Offline Offline
Faraday Member
**
Karma: 100
Posts: 4153
Where is your SSCCE?!?!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

What's a 16th note?  You working in some strange scale?

Here's all the percentages of each note up/down from a base note (A440 in this case): http://www.mixxx.org/wiki/doku.php/pitch_percentages_for_semitones_and_notes

The closest difference is around a 3%.

Logged

Get 10% off all 4D Systems TFT screens this month: use discount code MAJENKO10

the land of sun+snow
Offline Offline
Faraday Member
**
Karma: 159
Posts: 2916
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

It's unlikely to change 0.5% between successive notes in a song, may change
over minutes if the temperature changes. But you can "just do it", and test
it yourself in a few minutes.
Logged

Offline Offline
Full Member
***
Karma: 0
Posts: 222
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

16th are time divisions, not pitch.

While you say to "just do it", measuring timing accuracy isn't that straightforward.. How would you do it?
Logged

the land of sun+snow
Offline Offline
Faraday Member
**
Karma: 159
Posts: 2916
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

I meant if you're wanting to play music, just play it and see how it sounds. I
doubt the resonator timing will be an issue.
Logged

texas
Offline Offline
God Member
*****
Karma: 27
Posts: 862
old, but not dead
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I wanted to follow up on this.  I got myself another UNO board and the resonator on it is off by approx 350hZ.  This isn't allot, but it's a far cry from my first board that is only  about 50hZ off.  The serial numbers of the boards are pretty close, so I guess it was just a fluke that my first board had such an accurate resonator on it.  Resonator jitter doesn't seem to be an issue, but temperature variations are allot greater than with a crystal.  I'd still like to see a user mod option to route the USB crystal signal over to the mega chip by cutting a trace and installing a solder blob short.
Logged

Experience, it's what you get when you were expecting something else.

the land of sun+snow
Offline Offline
Faraday Member
**
Karma: 159
Posts: 2916
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Your frequency measurement might also depend upon which oscillator pin you are
probing. You will want to measure at the low-impedance output node of the oscillator,
and not the high-impedance input node, since your test device may load that pin.
Logged

texas
Offline Offline
God Member
*****
Karma: 27
Posts: 862
old, but not dead
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I am measuring it by running Timer1 as a 16 bit counter that ticks every .5uS.  I use a Dallas RTC to generate a 1Hz square wave output that I measure with the Arduino by counting how many timer ticks occur between interrupts from the square wave generator.  I'm using the capture facility to snapshot the timer so that any ISR handling delays or oscillator loading don't figure into it.
Logged

Experience, it's what you get when you were expecting something else.

Texas, land of the free, home of the stupid
Offline Offline
Sr. Member
****
Karma: 5
Posts: 268
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

afremont:  Why not just build a point-to-point with a crystal and two 22pF ceramics, and "replce" the resonator with the point-to-point?

      xtal
      |   |
      c   c
      - .--
        |
       gnd
Logged

texas
Offline Offline
God Member
*****
Karma: 27
Posts: 862
old, but not dead
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

afremont:  Why not just build a point-to-point with a crystal and two 22pF ceramics, and "replce" the resonator with the point-to-point?

      xtal
      |   |
      c   c
      - .--
        |
       gnd

Not enough room, for me anyway; it's just too small.  I'm not really unhappy, they still work very well.  I just go excited because I didn't notice it wasn't a crystal early on in my tinkering because it was right in the ballpark of what I would have expected from a cheap crystal.  When I figured out it was only a resonator, then I was impressed.  Just turns out I apparently just got lucky on the first one.
Logged

Experience, it's what you get when you were expecting something else.

Left Coast, CA (USA)
Offline Offline
Brattain Member
*****
Karma: 361
Posts: 17301
Measurement changes behavior
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

afremont:  Why not just build a point-to-point with a crystal and two 22pF ceramics, and "replce" the resonator with the point-to-point?

      xtal
      |   |
      c   c
      - .--
        |
       gnd

Not enough room, for me anyway; it's just too small.  I'm not really unhappy, they still work very well.  I just go excited because I didn't notice it wasn't a crystal early on in my tinkering because it was right in the ballpark of what I would have expected from a cheap crystal.  When I figured out it was only a resonator, then I was impressed.  Just turns out I apparently just got lucky on the first one.

There are crystal resonators, there are also ceramic resonators, those are both passive resonator components that will determine the frequency if wired into an oscillator circuit as the AVR has internal to the osc pins.

This all too common sloppy practice of calling a crystal resonator just a crystal and a ceramic resonator just a resonator has lead many beginners off to a rather poor understanding of such components and how they actually work.

Nothing personal, just a pet peeve.  smiley-wink

Lefty
« Last Edit: March 01, 2013, 07:07:26 pm by retrolefty » Logged

Dallas, TX
Offline Offline
Sr. Member
****
Karma: 10
Posts: 318
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
This all too common sloppy practice of calling a crystal resonator just a crystal and a ceramic resonator just a resonator has lead many beginners off to a rather poor understanding of such components and how they actually work.

Nothing personal, just a pet peeve. 

Lefty

How long has that sloppy practice been going on?
Logged

Left Coast, CA (USA)
Offline Offline
Brattain Member
*****
Karma: 361
Posts: 17301
Measurement changes behavior
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
This all too common sloppy practice of calling a crystal resonator just a crystal and a ceramic resonator just a resonator has lead many beginners off to a rather poor understanding of such components and how they actually work.

Nothing personal, just a pet peeve.  

Lefty

How long has that sloppy practice been going on?

Not sure but, too long in my opinion.  smiley-wink
But I will go along with your pet peeves if you go along with mine.

Lefty
Logged

UK
Offline Offline
Faraday Member
**
Karma: 100
Posts: 4153
Where is your SSCCE?!?!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
This all too common sloppy practice of calling a crystal resonator just a crystal and a ceramic resonator just a resonator has lead many beginners off to a rather poor understanding of such components and how they actually work.

Nothing personal, just a pet peeve.  

Lefty

How long has that sloppy practice been going on?

Not sure but, too long in my opinion.  smiley-wink
But I will go along with your pet peeves if you go along with mine.

Lefty

I've always known them as "crystals" and "resonators" since I can remember.  "Crystals" for bare quartz crystals, and "resonators" for either ceramic resonators, or combined quartz crystals with load capacitors.  Resonator, regardless of the technology in it, is distinct from crystal in that way.
Logged

Get 10% off all 4D Systems TFT screens this month: use discount code MAJENKO10

Dallas, TX
Offline Offline
Sr. Member
****
Karma: 10
Posts: 318
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
This all too common sloppy practice of calling a crystal resonator just a crystal and a ceramic resonator just a resonator has lead many beginners off to a rather poor understanding of such components and how they actually work.

Nothing personal, just a pet peeve.  

Lefty

How long has that sloppy practice been going on?

Not sure but, too long in my opinion.  smiley-wink
But I will go along with your pet peeves if you go along with mine.

Lefty

I'm cool with that.  smiley I just wondered because I never heard crystals called anything else until recently. I thought "crystal resonator" was coined to distinguish crystals from "ceramic resonators" which are more recent than crystals as a frequency generating/controlling device.
Logged

Left Coast, CA (USA)
Offline Offline
Brattain Member
*****
Karma: 361
Posts: 17301
Measurement changes behavior
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
This all too common sloppy practice of calling a crystal resonator just a crystal and a ceramic resonator just a resonator has lead many beginners off to a rather poor understanding of such components and how they actually work.

Nothing personal, just a pet peeve.  

Lefty

How long has that sloppy practice been going on?

Not sure but, too long in my opinion.  smiley-wink
But I will go along with your pet peeves if you go along with mine.

Lefty

I'm cool with that.  smiley I just wondered because I never heard crystals called anything else until recently. I thought "crystal resonator" was coined to distinguish crystals from "ceramic resonators" which are more recent than crystals as a frequency generating/controlling device.

Well it would different if people short cut it to crystal Vs ceramic but instead call it crystal Vs resonator when both are resonators just rubs me the wrong way. It's not unlike when a new comer might (and often do) asks if he should "use a transistor or use a mosfet to control a relay" and one then has to explain what the T in mosfet stands for.  smiley-wink

Lefty
Logged

Pages: 1 2 [3] 4   Go Up
Jump to: