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6.3.2 EXT2 header
PIN #
1
VDDA
3
VSS (AGND)
5
3.3V (VDD)
7
PA2
9
PC3
11
PA4
13
PC5
15
PB11
17
PB12
19
PB15
21
PC7
23
+5V_USB
25
GND_VSS
6.4 Jumper description
Please note that all of the jumpers on the board are SMD type. If you feel insecure in your
soldering/cutting technique it is better not to adjust the SMD jumpers.
6.4.1 BOOT memory select jumpers
B1_H/B1_L and B0_H/B0_L are SMD jumpers which define the initial boot default priority of the
microcontroller (aka which memory to boot from). By default they are set so that the board would
boot from the user Flash memory.
Notice that these two jumpers must be moved together – they are responsible for the boot mode if
bootloader is present. The board can search for bootloader on three places – either the user Flash
memory, the System memory, or the Embedded SRAM.
By default, B0_H/B0_L is set to position B0_L; the other jumper B1_H/B1_L is set to B1_L – in
this configuration the board will try to boot from user Flash memory.
To boot from the system memory you need to change the position of B0_H/B0_L jumper to position
B0_H. The boot loader is located in system memory (if you want to program the board via the USB
and DFUse software – use this mode).
Changing both high positions (B0_H/B0_L to B0_H; and B1_H/B1_L to B1_H) would attempt to
boot from the Embedded SRAM.
EXT2 HEADER
STM32H405 PIN
PIN #
2
4
6
8
10
12
14
16
18
20
22
24
26
Page 20 of 30
STM32-H405 user's manual
STM32H405 PIN
PC2
PA0
GND
PA1
PA3
PC4(USB_P)
PB10
PB13
PB14
PC6
PC8
PC9
VIN
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