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Questions tagged [crystal]

Piezo-electric device cut at a specific resonance frequency, mostly used in oscillators.

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Crystal Oscillator (STM32F4)

I am currently working with a STM32F427 MCU and have a few questions in my mind. Is my schematic for the HSE correct? Can you tell me, why some schematics on the Internet use a Resistor in series ...
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60 views

pcb-4-pin passive crystal is soldered to a 2-pin crystal PCB package

I would like to know whether it is suitable (not harmful) to put a 4 pin passive crystal in a 2 pin footprint. Thanks in advance. I have a 2 pin footprint in my PCB board,however,I only have a 4 pin ...
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3answers
63 views

Generate a false encoder signal CW/CCW 1/4 shifted

I need to generate a 10-100khz square signal freq. to simulate an encoder. I'd like to be able to simulate CW and CCW, shifted by 1/4 th signal. I've thinked about a crystal with a pot and some logic ...
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2answers
62 views

Designing a deterministic-startup precise oscillator

The problem I need to reliably generate a sequence of events based on a digital input trigger signal. With minimal jitter and a predictable deterministic delay. 2 to 5 events The events will be from ...
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25 views

How to change Oscillator Speed for the AT89c51 MCU?

My experience with embedded electronics is using ATMEGA328 with the arduino. I am aware that to change the crystal frequency from 16 MHz to 12 MHz on the ATMEGA328, requires a change to the final code,...
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19 views

Cutting liquid crystal valve

i need circular liquid crystal valve and I couldn't find anything on the internet. I've only found maybe 2 or 3 variants of it and that is square or rectangle so I was wondering if I can cut the lc ...
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2answers
52 views

How does load resistance affect the function of this crystal oscillator?

Related Load Resistor across Crystal - though that's for a passive crystal and not an integrated XO. Summary I'm considering using an Epson TG-5035C XO and am figuring out the circuit necessary to ...
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1answer
50 views

Does this clipped-sine oscillator need a buffer?

I'm considering using an Abracon VCTCXO, the ASVTX-11-121-19.200MHz-T to run an AT89LP428. I'm trying to make sure that they're interoperable, but the Abracon device doesn't say anything about the ...
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104 views

Why is my crystal oscillator not working with KSZ8999 switch?

I am using KSZ8999 ethernet switch from Micrel and I have problem with 25 MHz external oscillator. There is constant 2,1 VDC on output pin which is VDD for the switch, so crystal is not oscillating. ...
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2answers
398 views

Crystal compensation for temp and voltage

Introduction I'm toying with the design for a fail-safe wall clock controlled by multiple 32.768kHz crystal oscillators. I'm currently reading about compensation. Compensator from literature From ...
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48 views

{enc28j60} Is the 50ppm crystal good enough

I have some 25MHz 50ppm crystals but I am not sure if they are good enough to be used with ENC28J60.
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1answer
32 views

STM32F405 Internal vs External Oscillator

If the frequency stability over a temperature range is not a concern in a project instead it's reliability in continuous long time operation is a more important factor then which of the two ...
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162 views

32.768kHz crystal making audible noise

I am doing a project to record and log the voltages of an 8 cell lithium battery. The project is based on an STM32 microcontroller, and logging is done on an SD card. I have made the first version of ...
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1answer
46 views

Zero-R Resistor on XTAL pins

Looking at the schematics of the STM32F4-Discovery board page 28, whose screenshot is attached below.. there is a Zero Ohms resistor 'R25' which is shown in the circuit with the Crystal. And there is ...
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45 views

How to place parts crystal oscillator in DipTrace

I'm now into DipTrace and getting used to it. I placed parts by placing parts' standard like QFN-32, ESP8266EX etc... but I'cant find the way how to place a crystal oscillator. This is the one that ...
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2answers
47 views

STM32F407 fallback to Internal Osc

I wonder if it is possible at run time to detect that an external Oscillator has gone bad and the application now falls back to internal Oscillator.. specially for the case of STM32F407 MCU?
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1answer
71 views

Selecting true crystal settings for 328P [7.3728 MHz]

I want to make a new board working with 115200 (gsm modem) UART. so I want minimum baud error rate. I look at https://cache.amobbs.com/bbs_upload782111/files_22/ourdev_508497.html table and decide ...
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69 views

Problem configuring RTC of STM32F4 using LSE

I want to use RTC of STM32F4. When I configure this with LSI, I have no problem. But when I use LSE, I have a timeout error in SystemClock_Config function when it ...
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2answers
104 views

Testing crystal oscillator with multimeter crashes system

I have an old XT computer with a crystal oscillator that I would like to test. My multimeter has a Mhz setting that as far as I know should allow me to test it. (Providing the crystal is powered) ...
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129 views

Do crystals have polarity? [duplicate]

I have a quartz crystal and I am connecting it to a microcontroller's EXTAL and XTAL pins. Can I connect it anyway? Do the crystals have polarity? In EXTAL and XTAL, which is input and which is ...
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2answers
251 views

How do crystal oscillators start?

I have read the answers to the question,"How do crystal oscillator start to work" in this forum. And the common answer which I got is that, there are many frequency around the crystal. The crystal ...
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3answers
81 views

What is the purpose of capacitors parallel to crystal? [duplicate]

In many schematics, we have two capacitors connected in parallel to a crystal? Why do we have capacitors parallel to crystal? Whats the purpose? How are the capacitor values determined ?
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57 views

32khz crystal for AVR. Caps needed?

I remember reading long ago that I don't need filter caps for a watch (32768 Hz) crystal. Is this true? Or will I need to put some capacitors to ground on either end of the crystal? I will be using ...
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32 views

Programming AT89LP52 microcontroller like an AT89S52

I'm trying to run my code on the new AT89LP52 chip which Microchip (A.k.a. Atmel) believes can be a direct replacement for the AT89S52. I am able to program the AT89S52 with my programmer and ...
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1answer
107 views

Crystal oscillator replaced with exact frequency for clock?

I'm repairing my Nintendo Donkey Kong arcade PCB and I have no pulse when tested with my logic probe. I found out that the crystal oscillator (2 pin HC-18U) was not connected to the board, since the ...
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164 views

Confusing quartz crystal impedance graphs

I thought that at the series resonant frequency of a piezoelectric oscillator the impedance of the crystal would be the lowest, and at the parallel resonant frequency the impedance would be the ...
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3answers
137 views

What actually is the load capacitance of a quartz crystal?

I'm having hard time understanding the principles of piezoelectric crystal oscillators. I've found this picture: I understand that "load capacitance" is something you have to connect to a crystal. I ...
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3answers
164 views

Rectifying failed MCU crystal oscillator design

I am working on an SMD hobby project (2 layer board) where I use a STM32F405 MCU running at 3.3V, clocked from a 25MHz external crystal. Being impatient, I hastily designed a board and ordered it. ...
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3answers
77 views

Does Crystal/Oscillators package matter?

I design a lot of PCBs that uses microcontrollers with external clocks. For some reason a lot of the example designs always tend to use the big generic HC-49 package. Even factory made modules that I ...
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2answers
93 views

RTC time advancing

I'm working in some projects with an RTC. I'm using the PCF85063A. The problem is: the RTC counter is advancing from real time about 2 minutes per week. I searched for hardware and firmware errors, ...
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2answers
466 views

What is the purpose of this extra PCB pad?

I am looking to use this crystal in an upcoming design and I am a little bit confused by the datasheet. The datasheet is available here: CMR200T Datasheet This is the image in question: Question: ...
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1answer
52 views

Crystal Oscillator Power

In the following circuit: taken from: https://circuitdigest.com/tutorial/quartz-crystal-oscillator How is the crystal powered to begin oscillation? I understand the amplifier is required to prevent ...
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2answers
232 views

Why does this crystal oscillator have a window?

I came across this device just now, and I can't think of any reason for it to have the window that it has. This isn't just a cutaway display image, either; the datasheet specifically mentions that ...
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2answers
73 views

Is an external crystal overkill is this case?

I am designing some boards that are powered and communicate through Cat 5 cables using a bit banged form of protocol inspired by quad spi. Using the bus network topology in a half duplex manner, I ...
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3answers
130 views

Why does antenna tuner in crystal radio use capacitor and an inductor?

I know that antennas can be capacitive or inductive depending on the relation of antenna length to the \$\lambda\$. I know that crystal radios use both antenna and capacitor for tuning and I don't ...
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2answers
82 views

Speaker for crystal radio rather than sensitive piezoelectric speaker Crystal radio

I am a science student of grade 8 and researching and learning about radio waves. I am currently trying to make a crystal radio. The problem I am facing is the speaker I have to use for the project....
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2answers
300 views

Sharing 32.768kHz crystal for 2 IC [duplicate]

Is it possible to share 32.768kHz crystal for nRF52 and BNO055? The purpose is reducing cost&space. Preferred crystal this one: FC-135R https://support.epson.biz/td/api/doc_check.php?dl=...
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1answer
40 views

Byte-Banging 2 8051's using port addresses

Currently I have two microcontrollers setup in which entire ports are connected to each other (P1.1 connected to P1.1, P1.2 connected to P1.2, etc). I also have two pairs of extra GPIO pins connected ...
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1answer
76 views

Crystal 4 Pins SMD footprint

I'm designing PCB that includes 24MHz SMD 4 pins crystal. According to my understanding, the crystal package marking is for Pin number 4. I wonder, how should I indicate in the PCB this pin? Should ...
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48 views

Minimalist high speed 8051 microcontroller testing circuit on breadboard

I'm trying to come up with a circuit using the least number of parts possible to build on a breadboard that tests the basic functionality of a microcontroller, specifically the AT89LP4052 ...
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1answer
137 views

Separate GND-plane for microcontroller crystal resonator

1.  Background info I'm designing a board for an STM32F767ZI microcontroller. This microcontroller has a primary oscillator for the SYSCLK (overall system ...
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1answer
68 views

How do I keep my LEDs from burning out in a magnetic induction coil?

I built a simple magnetic inductance coil using: For transmitter: 28 awg magnet wire in a "pancake coil" (flat spiral) npn transistor (TIP31C) 2 resistors in parallel battery (tried a 3 volt ...
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0answers
53 views

AT89S52 microcontroller only starts when extra 22uF capacitor touches board

I made simple code for the microcontroller that prints a simple message on the LCD once the microcontroller starts. I arranged my board so that the pull-up resistors and reset resistor (100K) and ...
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1answer
225 views

XTAL resonance increase the voltage

I have a 4Mhz crystal and i connect it in series between the function generator and the oscilloscope probe as shown below: simulate this circuit – Schematic created using CircuitLab However i ...
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1answer
388 views

Frequency response of MCU decoupling capacitor

I'm designing a board that contains an MCU and an 8 MHz crystal. I was planning on keeping the MCU power/ground localized and isolated from the main power supply power/ground except at a single point. ...
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2answers
210 views

32.768 kHz Crystal Troubleshooting

I'm at my wit's end trying to get a 32.768 kHz tuning fork crystal to work and I don't know what I'm doing wrong. First, some background: I'm using a 16MHz crystal in conjunction with an Atmega 328P-...
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1answer
390 views

Why do some Arduino-compatible boards provide a crystal for the CH340? [closed]

I have an uno-shaped Arduino compatible which uses the CH340(G) serial to ttl converter chip and it is connected to an external crystal. I also have nano shaped compatible which uses the CH340(C) ...
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1answer
44 views

IN/OUT pin of the crystal circuits [duplicate]

Got few questions about the input/output pins of a crystal circuit. As shown above, it's a common clock circuits. My question is: 1. If we want to measure the waveform of the clock, which pin should ...
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3answers
196 views

Can I get away with that poorly designed board?

I am designing a board but space is not a luxury that I have at the moment, can I get away with that design or I must use a SMD resonator?
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2answers
89 views

Is it better on two closely connected microcontrollers to send nibbles with an ack or a byte with a delay for an ack?

I'm trying to figure out the best approach to transfer high-speed data one way between two microcontrollers (with their own crystals of the same speed) of the same variety (between AT89C4051 and ...