I am using the NUCLEO-L073RZ development board. When looking at the documentation, it seems that the STM32 MCU (U5) on this dev board uses an external HSE clock signal from the programmer MCU (U2) on the top portion of the board. This MCU (U2), in turn, seems to get it's clock signal from an 8 Mhz crystal oscillator (X1).
This was confirmed when looking at the value of the RCC_CR register:
00000011 00000111 00000011 00000000
From what I understand, this indicates that the HSE clock source is ready and being used.
I am now trying to use U5 independently from U2. I would like to use the same 8 Mhz crystal, therefore I soldered it to the X3 location, connected R35 and R37, and added 20pF capacitors to C33 and C34, as depicted in the documentation. I also removed SB50, to disconnect the clock signal from U2.
However, this does not seem to be working. When looking at the value of the RCC_CR register:
00000011 00000101 00000011 00000101
From what I understand, this indicates the the HSE clock source is not ready, and therefore the internal clock source is being used.
Can anyone help me to understand what I am doing wrong?
