AnsweredAssumed Answered

Recommended Oscillator for STM32F407

Question asked by chauhan.samir on Jan 25, 2013
Latest reply on Jan 25, 2013 by Andrew Neil
I have designed a custom board around STM32F407VET.  I am using 8 MHz external oscillator (ABRACON ABLS-8.000MHZ-B2-T) with 22 pf load capacitors (CL) and 220 ohm REXT.  When I probe OSC_IN or OSC_OUT pins using logic analyzer I see no oscillation.  I have tried various values of CL from 18 pf to 27 pf and REXT from 120 to 470 ohm with no success.  I measure the correct frequeny on STMF4 Discovery kit with my set up.  Since external oscillator is not working the microcontroller automatically switches to internal oscillator and I am able to program the board.  However, I would like to use the external oscillator as planned.  I would appreciate if someone can recommend oscillator part number, CL and REXT values that they have used in the past and are known to work with STM32F4xx series.