Hardware layout and configuration
UM2032
20/40
UM2032 Rev 3
5.4 Clock
source
5.4.1 HSE
clock
source
By default the 8 MHz clock source is provided to the STM32F412ZGT6 by the MCO output
of the ST-LINK/V2-1 MCU U6. In that case the solder bridge SB20 is ON, resistors R45 and
R46 are not soldered, solder bridge SB22 is OFF. The pins PH0 and PH1 are not available
for the extension connector P2.
Alternatively, the Discovery kit offers the possibility to use a crystal to provide the 8 MHz
HSE clock source of the STM32F412ZGT6 U7. In that case, PH0 and PH1 are used as
OSC_IN and OSC_OUT respectively. The solder bridges SB20, SB22, SB16 must be OFF,
0 ohm resistors should be soldered to R45 and R46 and a crystal must be soldered in place
X2. Regarding component selection of X2, capacitors C19 and C21 (8.2 pF) are optimized
for a 8 MHz crystal and they are OFF. The pins PH0 and PH1 are not available for the
extension connector P2.
5.4.2 LSE
clock
source
By default, the 32.768 kHz crystal X3 is connected to pins PC14-OSC32_IN and PC15-
OSC32_OUT of STM32F412ZGT6 for the RTC clock. Solder bridges SB25 and SB23 must
be OFF.
If LSE clock is not used, it is possible to use PC14-OSC32_IN and PC15-OSC32_OUT of
STM32F412ZGT6 and to access by the extension connector P2. In that case, solder
bridges SB25 and SB23 must be ON and resistors R54, R56 removed.
5.5
Reserved use of solder bridges
The following solder bridges must not be changed otherwise the microcontroller
STM32F412ZGT6 U7 or other parts of the Discovery kit may be damaged:
•
Solder bridges must be left ON: SB34, SB26
•
Solder bridges must be left OFF: SB27, SB35
5.6 Reset
source
The reset signal of 32F412GDISCOVERY Discovery kit is low active and the reset sources
include:
•
Reset button B1, providing solder bridge SB1 is ON (default setting)
•
Embedded
ST-LINK/V2-1, providing solder bridge SB21 is ON (default setting)
•
ARDUINO
®
Uno V3 compatible connector CN2 pin 3
•
Extension connector P1 pin 6
