Mother Board Reset Sources; Mother Board Boot Options; Table 3. Boot Settings - STMicroelectronics UM2322 User Manual

Hardware layout and configuration
The following power sequence procedure must be respected:
1. Put a jumper in JP3 at location U5V to use power from user USB CN8 or at location
E5V to use power from VIN of Arduino connector CN15.
2. Connect the corresponding external power source.
3. Check the green LED LD8 is turned ON.
4. Connect the PC to ST-LINK/V2-1 USB connector CN5.
If this order is not respected, the board may be powered by VBUS first from ST-LINK, and
the following risks may be encountered:
1. If more than 500 mA current is needed by the board, the PC may be damaged or
current may be limited by PC. As a consequence the board is not powered correctly.
2. 500 mA is requested at the enumeration, so there is a risk that the request is rejected
and enumeration does not succeed if PC does not provide such current.
7.5

Mother board reset sources

The reset signal of the STM32L496AGI6-based Discovery mother board is low active and
the reset sources include:
•
Reset button B1
•
Embedded ST-LINK/V2-1, SW1 set to ON (default setting)
•
Arduino compatible TM connector CN15 pin 3
7.6

Mother board boot options

After reset, the microcontroller STM32L496AGI6 may boot from the 3 following embedded
memory locations depending on bits BOOT0 and BOOT1:
•
Boot from the user FLASH memory
•
Boot from the ICP (In Circuit Programming)
•
Boot from the SRAM
The selection of the memory space for the boot is done by two bits, BOOT0 and BOOT1.
The value of BOOT1 is defined by a user option bit (bit[23], nBOOT1). Specifically, when
this bit is written with '1', the empty flag status toggles and keeps this new status until the
next OBL or until a new '1' is written.
nBOOT1 nBOOT0
(OPTR[23]) (OPTR[27])
X
X
1
12/22

Table 3. Boot settings

BOOT0 pin
(PH3)
X 0
X 0
X 1
BOOT0 SW
Main Flash
configuration
empty
OPTR[26])
1 0
1 1
1 X
UM2322 Rev 2
UM2322
Boot memory space alias
User FLASH memory is aliased
at address 0x0000_0000
Test FLASH memory is aliased
at address 0x0000_0000
Test FLASH memory is aliased
at address 0x0000_0000