# Using a 2pin 32khz crystal instead of a smd crystal? **URL:** \ **Category:** 3rd Party Boards\ **Created:** [December 27, 2023, 9:18pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388 "2023-12-27T21:18:38Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![josephchrzempiec](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/josephchrzempiec/32/216668_2.png) [@josephchrzempiec](https://forum.arduino.cc/u/josephchrzempiec)\ **Post date:** [December 27, 2023, 9:18pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/1 "2023-12-27T21:18:38Z")
Hellio, I have a bunch of the samd21 processors I was very successful in putting a bootload as well as a bink sketch on the processor using the arduino zero bootloader. I'm with a help of a friend soon to build my own pcb for it. My problem is I have a hard time soldering smd crystal. I was wonder If I follow the wiring for the crystal can I use one of the 2pin crystal with a 2 pin through hole And Would it work the same way? Joseph ---
**Author:** ![anon94801460](https://avatars.discourse-cdn.com/v4/letter/a/278dde/32.png) [@anon94801460](https://forum.arduino.cc/u/anon94801460)\ **Post date:** [December 27, 2023, 9:27pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/2 "2023-12-27T21:27:51Z")
Sure. Don't forget the two required capacitors, typ. 30 pF. ---
**Author:** ![josephchrzempiec](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/josephchrzempiec/32/216668_2.png) [@josephchrzempiec](https://forum.arduino.cc/u/josephchrzempiec)\ **Post date:** [December 27, 2023, 9:37pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/3 "2023-12-27T21:37:46Z")
Hello, Yes He has including them. He never design a micro processor before. But he has done a lot of relay board and a few other things. He is still new to all designing. I really want to see if he can do it. He is following this Schmetic [https://cdn-shop.adafruit.com/product-files/2843/Arduino-Zero-schematic.pdf](https://cdn-shop.adafruit.com/product-files/2843/Arduino-Zero-schematic.pdf). But the crystal looks like it is using 6.8 Not 30 as you are saying to use. Should he be using 30 instead of 6.8? ---
**Author:** ![anon94801460](https://avatars.discourse-cdn.com/v4/letter/a/278dde/32.png) [@anon94801460](https://forum.arduino.cc/u/anon94801460)\ **Post date:** [December 27, 2023, 9:41pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/4 "2023-12-27T21:41:18Z")
The recommended crystal load capacitance is stated in the crystal data sheet, which includes stray PCB capacitance. The capacitors are effectively in series, so the total load capacitance is the series combination of the two you use, with stray PCB capacitance in parallel to the series combination. ---
**Author:** ![josephchrzempiec](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/josephchrzempiec/32/216668_2.png) [@josephchrzempiec](https://forum.arduino.cc/u/josephchrzempiec)\ **Post date:** [December 27, 2023, 9:42pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/5 "2023-12-27T21:42:42Z")
I don't have the link for the correct datasheet to take a look at. Can you please share with me the link? ---
**Author:** ![anon94801460](https://avatars.discourse-cdn.com/v4/letter/a/278dde/32.png) [@anon94801460](https://forum.arduino.cc/u/anon94801460)\ **Post date:** [December 27, 2023, 9:44pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/6 "2023-12-27T21:44:02Z")
I have no idea what crystal you have. If you don't either, buy a crystal with a data sheet. ---
**Author:** ![josephchrzempiec](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/josephchrzempiec/32/216668_2.png) [@josephchrzempiec](https://forum.arduino.cc/u/josephchrzempiec)\ **Post date:** [December 27, 2023, 9:45pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/7 "2023-12-27T21:45:51Z")
I got them from mouser. This is the ones I have [https://www.mouser.com/ProductDetail/ECS/ECS-.320-12.5-13X?qs=sGAEpiMZZMsBj6bBr9Q9aTum9kEjld92o7ROYXbf8uI%3D](https://www.mouser.com/ProductDetail/ECS/ECS-.320-12.5-13X?qs=sGAEpiMZZMsBj6bBr9Q9aTum9kEjld92o7ROYXbf8uI%3D). ---
**Author:** ![anon94801460](https://avatars.discourse-cdn.com/v4/letter/a/278dde/32.png) [@anon94801460](https://forum.arduino.cc/u/anon94801460)\ **Post date:** [December 27, 2023, 9:46pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/8 "2023-12-27T21:46:57Z")
Then get the data sheet from Mouser. There should be a link on the product page. If not, ask. ---
**Author:** ![josephchrzempiec](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/josephchrzempiec/32/216668_2.png) [@josephchrzempiec](https://forum.arduino.cc/u/josephchrzempiec)\ **Post date:** [December 27, 2023, 9:48pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/9 "2023-12-27T21:48:55Z")
Oh i see. I thought there was a arduino schmetic I need to look at. ---
**Author:** ![wvmarle](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/wvmarle/32/1013044_2.png) [@wvmarle](https://forum.arduino.cc/u/wvmarle)\ **Post date:** [December 28, 2023, 7:25pm UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/10 "2023-12-28T19:25:03Z")
A schematic is a diagram of parts and how they are connected. A datasheet is detailed information on a particular part - usually electrical and mechanical. The datasheet you need in this case to find out what load capacitance is needed. For your PCB design: keep the crystal close to the MCU, and the load caps right next to it. Keep traces as short as possible. If your load capacitance is much off, the frequency of the crystal may be off, or it may not start oscillating at all. ---
**Author:** ![Paul\_KD7HB](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paul_kd7hb/32/1127958_2.png) [@Paul\_KD7HB](https://forum.arduino.cc/u/Paul_KD7HB)\ **Post date:** [December 29, 2023, 1:18am UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/11 "2023-12-29T01:18:55Z")
The data sheet for the crystal that was linked to is for a "tuning fork crystal". Completely wrong for any microcontroller. ---
**Author:** ![anon94801460](https://avatars.discourse-cdn.com/v4/letter/a/278dde/32.png) [@anon94801460](https://forum.arduino.cc/u/anon94801460)\ **Post date:** [December 29, 2023, 1:20am UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/12 "2023-12-29T01:20:46Z")
I think the selected crystal will work fine on the RTC oscillator input. Caps should be about 22 pF each, and the board capacitance will add other few, so the total load will be \> 12 pF. ---
**Author:** ![josephchrzempiec](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/josephchrzempiec/32/216668_2.png) [@josephchrzempiec](https://forum.arduino.cc/u/josephchrzempiec)\ **Post date:** [December 29, 2023, 1:24am UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/13 "2023-12-29T01:24:18Z")
I didn't know If I needed to go by the schematic from the data sheet of the crystal or what I found online. This is all new to me. I'm learning as I go along, I will make mistakes. But it's cool trying to learn to build my own PCB. and figuring out the traces and what not. ---
**Author:** ![josephchrzempiec](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/josephchrzempiec/32/216668_2.png) [@josephchrzempiec](https://forum.arduino.cc/u/josephchrzempiec)\ **Post date:** [December 29, 2023, 1:25am UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/14 "2023-12-29T01:25:03Z")
Thank you. That is what I thought as well. But I wasn't sure if 12pf was correct or not. ---
**Author:** ![anon94801460](https://avatars.discourse-cdn.com/v4/letter/a/278dde/32.png) [@anon94801460](https://forum.arduino.cc/u/anon94801460)\ **Post date:** [December 29, 2023, 1:27am UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/15 "2023-12-29T01:27:42Z")
> [@josephchrzempiec](#): > > 12pf The data sheet says 12.5 pF. ---
**Author:** ![josephchrzempiec](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/josephchrzempiec/32/216668_2.png) [@josephchrzempiec](https://forum.arduino.cc/u/josephchrzempiec)\ **Post date:** [December 29, 2023, 1:32am UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/16 "2023-12-29T01:32:56Z")
I saw that. I just wasn't sure. Thank you. ---
**Author:** ![anon94801460](https://avatars.discourse-cdn.com/v4/letter/a/278dde/32.png) [@anon94801460](https://forum.arduino.cc/u/anon94801460)\ **Post date:** [December 29, 2023, 1:52am UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/17 "2023-12-29T01:52:36Z")
The data sheet is your very best and most reliable source of information. ---
**Author:** ![Paul\_KD7HB](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paul_kd7hb/32/1127958_2.png) [@Paul\_KD7HB](https://forum.arduino.cc/u/Paul_KD7HB)\ **Post date:** [December 29, 2023, 3:41am UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/18 "2023-12-29T03:41:58Z")
I did not understand the crystal was meant for a clock. Does the clock have any way to make corrections for the crystal frequency? If not and exact frequency is needed, several crystals might be tried to find a correct one for the device. ---
**Author:** ![anon94801460](https://avatars.discourse-cdn.com/v4/letter/a/278dde/32.png) [@anon94801460](https://forum.arduino.cc/u/anon94801460)\ **Post date:** [December 29, 2023, 3:44am UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/19 "2023-12-29T03:44:27Z")
> [@Paul\_KD7HB](#): > > was meant for a clock The RTC/reference clock oscillator on the SAMD21 processor. Sparkfun uses 2x15 pF on their SAMD21 breakout board. ![Capture](https://europe1.discourse-cdn.com/arduino/original/4X/5/d/c/5dcdb17e75123bdf7bc646aa2d6c87d3244095a5.png) ---
**Author:** ![josephchrzempiec](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/josephchrzempiec/32/216668_2.png) [@josephchrzempiec](https://forum.arduino.cc/u/josephchrzempiec)\ **Post date:** [December 29, 2023, 10:25am UTC](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388/20 "2023-12-29T10:25:39Z")
Hello all, Thank you for the help and information. Should I be using a 12pf cap or what adafruit said and put a 15pf cap? If I'm going by the datasheet of the crystal then it is a 12pf cap. [Next page](https://forum.arduino.cc/t/using-a-2pin-32khz-crystal-instead-of-a-smd-crystal/1204388.md?page=2)