Try this: atmel-2521-avr-hardware-design-considerations_applicationnote_avr042. I think, more important for you could be PCB design. Usually it is solved by using of separate RTC like DS3231 with 1Hz output to INT input of 328P. However, 328P shares pins for main crystal and clock crystal and in adition 32kHz is too slow for performance. If precise timing is needed, like for clock application, then it is better to use RTC circuit or to use 32768Hz clock crystal. It has impact to frequency offset, slightly higher or lower, as was mentioned above. The value is not so important but should be within recommended range. Datasheet for ATmega328P definitely says the capacitors are needed. It can depend on MCU type, exactly its oscillator circuit. If someone could provide us with more in depth knowledge in case I got something wrong please let us know! Hope that by sharing what I found I help people looking for the same answers in the future. From what I understood from this discussion any NP0 multilayer ceramic capacitor will work sufficiently. I was wondering if multilayer ceramic caps are suitable instead of the through hole ceramic capacitors everybody is using.
However, as he explained resonators have a capacitive element built in which eliminate the need for external capacitors.įurthermore just one question persists.
Arduino nano schematic crystal or resonator Bluetooth#
I am planning to communicate over bluetooth to another chip in this project in the future so that's why I want to stay with the crystal. He explains that over time the timing of resonators might become offset and might pose difficulty when communicating between chips. I have seen the HC-49S come across more often in other projects so I decided to just go with this one.Īs for the decision to go for a crystal over a resonator I reference this video by Derek Molloy. He very kindly specified the source from where he bought the crystal in the description of the video in which we find that he used a HC-49S, 16MHz, 20pF load capacitance, frequency tolerance of +/- 20ppm. I found one source that clearly references the specs of the crystal with proof it works.
The resonator can be a (quartz) crystal, which is accurate and. In the end I see a lot of sources just say 16MHz and two 22pF. The circuit is usually a feedback loop around a frequency determining element or resonator. Many sources on the internet just specify a 16MHz crystal without specifying the load capacitance of the crystal they use. It has been a frustrating process to find a straight answer.
I have been reading many forum posts on different forums that ask about the same question I asked here.
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