Solder bridges UM2271
50/78 DocID030906 Rev 2
Appendix B Solder bridges
Following Table 30 describes each solder bridge. The default state is indicated in bold. ON state means a 0 ohm resistor is
soldered. OFF state means SBxx is open.
Table 30. 32L4R9IDISCOVERY solder bridges
Solder bridges State Description
SB2 (ARD_D13 Green LED)
ON Enables ARD Green LED control by ARD_D13
OFF Disables ARD Green LED
SB27 (ARD_AVDD on VREF+)
ON Connects VREF+ from MCU to ARD_AVDD
OFF ARD_AVDD not connected
SB32, SB34 (I2C3 on ARD_A4/A5) OFF I2C3 disconnected from ARD_A4/A5, exclusive with SB33, SB35
SB33, SB35 (ADCs on ARD_A4/A5) ON ADCs inputs connected to ARD_A4/A5, exclusive with SB32, SB34
SB7, SB13 (USART3 on DSI display) OFF Disconnects USART3_CK/TX from pins 24/26 of DSI V3 connector, exclusive with SB6 and SB8
SB6, SB8 (SPI2 on DSI display) ON Connects SPI2_SCK/MOSI to pins 24/26 of DSI V3 connector, exclusive with SB7 and SB13
SB23 (VDD on OCTOSPI Flash)
ON Connects OCTOSPI Flash power rails to VDD
OFF Disconnects VDD from OCTOSPI Flash
SB25 (OCTOSPI_ECS)
ON ECS function active (need external pull-up)
OFF ECS function not active (no external pull-up)
SB24 (OCTOSPI_RESET)
ON OCTOSPI Flash Reset is connected to General Reset of Board
OFF OCTOSPI Flash Reset not connected to General Reset of Board
SB1 (DFSDM_1_DATIN1)
ON PB12 (DFSDM_1_DATIN1) is connected to Digital Microphones by default
OFF PB12 (DFSDM_1_DATIN1) is usable by STMod+ on pin 17
SB3 (RESERVED) ON Reserved, but can be removed if necessary (PSRAM_A20 to U6)
SB4 (RESERVED) OFF Reserved, do not modify (PSRAM_A20 to VDD)
SB16, SB17, SB18, SB19, SB20, SB21
(RESERVED)
OFF Reserved, (STMod+/PMOD)
SB36 (RESERVED) OFF Reserved, (STLINK)
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