Large Range values crystal to microcontrollers  - Page 1
Forum section: electronics / beginners

author: Jasonbit
author_rank: Regular Contributor
timestamp: August 09, 2018, 11:47:51 pm
content: Hello Folks,I am upset with all microcontrollers. Because I every time I need a crystal I never have the right crystalTherefore I ask help you to find kit in any online store where offer a large suggest the most number possible of values crystal. Or if you can give me a list of values do you thinking, with your experience, I will need in future, I will appreciate.ThanksI find many package where I can find a various values of crystal, like this:https://www.ebay.com/itm/15PCS-Values-Crystal-Oscillator-Assortment-4-48MHZ-Kit-Set-DIP-DIY-New/311647168836?hash=item488f9e6944%3Ag%3A8Z0AAOSwnHZYcGhl&_fsrp=1&_sacat=7286&_nkw=kit+values+crystal&_from=R40&rt=nc&_trksid=m570.l1313&LH_TitleDesc=0%7C0,but always I am in doubt if this are the right values for me. I am a newbie in world microcontrollers. I am use a family PIC16 and ATMEGA.

author: bson
author_rank: Unknown
timestamp: August 10, 2018, 04:23:57 am
content: You need to know the load capacitance of a crystal. I see nothing in that listing and I suspect that information won't be included. Just order an assortment of e.g. Abracon crystals from a reputable distributor. Basic jellybean crystals are not expensive.

author: james_s
author_rank: Super Contributor
timestamp: August 10, 2018, 05:21:20 am
content: How many different crystals do you need? I find that 2 or 3 different values cover 99% of my needs.

author: Jasonbit
author_rank: Regular Contributor
timestamp: August 10, 2018, 02:50:57 pm
content: Quote from: bson on August 10, 2018, 04:23:57 amWhat reputable distributor do you know? This distributor available samples, like microchip for example?I am a newbie on electronics, do you refer this,https://www.foxonline.com/pdfs/xtaldesignnotes.pdf, when talk about load capacitance of a crystal?QuoteQuote from: james_s on August 10, 2018, 05:21:20 amTo right now I only need 4MHz and 16MHz, but to reduce breakages I prefer to gather a variety of values, to avoid problems in a future.Thanks

author: bson
author_rank: Unknown
timestamp: August 10, 2018, 09:05:39 pm
content: Quote from: Jasonbit on August 10, 2018, 02:50:57 pmhttps://blog.adafruit.com/2012/01/24/choosing-the-right-crystal-and-caps-for-your-design/I usually order from Mouser or DigiKey, but you're in the U.K. and I don't know what distributors exist in Europe... I can't really help other than strongly suggest not buying random parts without proper datasheets on eBay.For MCUs I like 12MHz since this is easily scaled to just about anything using an internal PLL (it factors to powers of the two smallest primes, 2 and 3 so can trivially PLL scale to any product of powers of 2 and 3), especially with simpler MCU PLLs that often limit nominator or denominator to a power of two. PLLs and DCOs can be tricky to set up on a chip I'm unfamiliar with, so I like to be able to punt on that and just run directly off the external crystal osc only to make progress, then revisit the DCO and PLL later. More specifically, when I have pin configuration, clock selections, and other internal features going, so I can route clocks to an external pin and measure them with a counter to verify it's all working as intended.

author: blackfin76
author_rank: Regular Contributor
timestamp: August 10, 2018, 09:58:15 pm
content: Quote from: bson on August 10, 2018, 09:05:39 pmMouser, Digikey, Farnell/element14, RS components just to name a few.Mouser and Digikey are now just as easy to order from in Europe since the have local representation.