Wich crystal can i use

Using Arduino Microcontrollers
1

this Crystal

can i use it with Atmega 328p ?

2

Sure, any normal crystal is okay.
If you buy a clone on AliExpress/Ebay/Amazon, then the crystal is much worse quality than the one that you have selected, and even those much worse crystals work.
The ATmega328P runs at 16MHz with 5V, and the crystal is only 8MHz.
There are also resonators, and the ATmega328P has an internal oscillator.

There are 22pF capacitors around the crystal, but some crystals prefer a lower value.

Don't start three topics that are basically the same.

1 Like
3

i made a simple Schematic, that startet just when one of two signal come .
the signal turn on the N-Mosfet . signal come from other Arduino chip .

after the circuit startet ,it will sending the information with LoRa

can someone check my Design Please ?
i will programming it with FTDI .
i will using this Crystal 8 MHZ
the Bat give me 3 V
c4 c5 100nF
c2 c3 22pF

Unbenannt
Unbenannt1313×800 15.4 KB

5

If you are proposing to operate with no crystal or ceramic resonator, then using a serial interface may not work so well.

The two main problems here are

  1. Re-inventing the wheel. If you want a 3.3 V "Arduino", an 8 MHz Pro Mini clone is inexpensive and easier/ cheaper than building your own.

  2. The Pro Mini does not include the USB interface. You use a separate adapter to program it. the point is, you do not use battery power and connect by USB, so you want to decide for one or the other. If it will connect to USB, you use a Nano (clone), if batteries, then a 3.3 V Pro Mini.

6

Your two topics on the same or similar subject have been merged.

Please do not duplicate your questions as doing so wastes the time and effort of the volunteers trying to help you as they are then answering the same thing in different places.

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Thanks to all those who helped and added to this list.

Thank you.

7

Often a larger capacitor is added to VCC and GND.

The /RESET is missing a diode to VCC, the firmware might get corrupted when the /RESET pin turns into High Voltage mode by the DTR signal.

A inductor to AVCC also needs a capacitor of 100nF at AVCC.

A led with 330Ω is good, but its brightness depends a lot on the color of the led (forward voltage drop depends on color).

A RX pin that floats might cause interrupts because the ATmega328P might see start bits. You can add a resistor of 10k from RX to VCC. It is idle high.

I'm not sure about the low-side switching of the battery.

8

is the contact with LoRa RA-02 True ?

9

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