UM1670 Rev 4 21/32
UM1670 Hardware layout
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6.13 Solder bridges
Table 6. Solder bridges 
Bridge State 
(1)
1. The default SBx state is shown in bold.
Description
SB19, 20 (X3 crystal)
OFF 
X3, C20, C21, R56, and R57 provide a clock. PH0 and PH1 are disconnected 
from P2.
ON  PH0 and PH1 are connected to P2. Remove only R56 and R57.
SB4, 6, 8,14 (default)  ON  Reserved, do not modify.
SB3, 5, 7,13 (reserved) OFF  Reserved, do not modify.
SB22, 23, 24, 25 OFF  Reserved, do not modify.
SB16, 17 (X2 crystal) 
OFF 
X2, C23, C24, R53, and R54 deliver a 32 kHz clock.  
PC14 and PC15 are not connected to P2
ON 
PC14 and PC15 are only connected to P2. 
Remove only R53 and R54.
SB1 (B2-RESET) 
ON  B2 push-button is connected to the NRST of STM32F429ZIT6.
OFF  B2 push-button is not connected to the NRST of STM32F429ZIT6.
SB2 (B1-USER)
ON  B1 push-button is connected to PA0.
OFF  B1 push-button is not connected to PA0.
SB11, 15 (RX,TX)
OFF 
STM32F429 USART1 is not connected to ST-LINK, so VCP is disabled 
(Default configuration on 32F429IDISCOVERY).
ON 
STM32F429 USART1 is connected to ST-LINK, so VCP is enabled (default 
configuration on STM32F429I-DISC1).
SB12 (NRST) 
ON  NRST signal of connector CN2 is connected to the NRST of STM32F429ZIT6.
OFF  NRST signal is not connected.
SB9 (SWO) 
OFF  SWO signal is not connected.
ON  SWO signal of connector CN2 is connected to PB3.
SB10 (STM_RST) 
OFF  No incidence on the NRST signal of STM32F429ZIT6.
ON  NRST signal of STM32F429ZIT6 is connected to GND.
SB21 (BOOT0) 
ON  BOOT0 signal of STM32F429ZIT6 is at level LOW through 510 
Ω pull-down.
OFF 
BOOT0 signal of STM32F429ZIT6 is at level HIGH through 10 K
Ω pull-up (not 
provided).
SB26, 27 (USB OTG) 
OFF 
PB14 and PB15 are only used for USB OTG and not connected to P2 to avoid 
noise.
ON  PB14 and PB15 are connected to P2.
SB18 (MCO)
OFF  MCO signal of STM32F429ZIT6 is not used.
ON 
MCO clock signal from STM32F429ZIT6 is connected to OSC_IN of 
STM32F429ZIT6.