change resonator with crystal

clran

Dear all,

I'm using a microcontroller board with 8 MHz ceramic resonator(3 legs). However, the frequency of the resonator does not allow me to achieve a baud rate of 115200bps. Therefore, i need to replace it with a 7.3728MHz ceramic resonator (3 legs) in order to get the 115200bps baud rate. Sadly, i was unable to found the 7.3728MHz ceramic resonator but i did found quartz crystal (2 legs) with 7.3728MHz frequency. I was told that if i replace the ceramic resonator with the quartz crystal, i need to include 2 capacitor, C1 and C2. However, how do i know what the value of capacitor that i need to use? Please help! If there is better solution, please let me know.

Thanks!

Regards,
Jackie Wong

anthrax11

: Dear all,
:
: I'm using a microcontroller board with 8 MHz ceramic resonator(3 legs). However, the frequency of the resonator does not allow me to achieve a baud rate of 115200bps. Therefore, i need to replace it with a 7.3728MHz ceramic resonator (3 legs) in order to get the 115200bps baud rate. Sadly, i was unable to found the 7.3728MHz ceramic resonator but i did found quartz crystal (2 legs) with 7.3728MHz frequency. I was told that if i replace the ceramic resonator with the quartz crystal, i need to include 2 capacitor, C1 and C2. However, how do i know what the value of capacitor that i need to use? Please help! If there is better solution, please let me know.
:
: Thanks!
:
: Regards,
: Jackie Wong
:

15-33 picofarads is common. In case you wondered or didn`t know why you need the capacitors - they help to make the crystal oscillate better and make it more stable. The 3-leg ceramic resonator already had the caps built in.
Good luck!