AT-START-F407 User Manual
2020.11.20
11
Rev 1.20
3.4
Boot mode selection
At startup, three different boot modes can be selected by means of the pin configuration.
Table 1. Boot mode selection jumper setting
Jumper
Boot mode selection
pins
Setting
BOOT1
BOOT0
JP1 connected to GND or OFF;
JP4 optional or OFF
X
(1)
0
Boot from the internal Flash memory
(Factory default setting)
JP1 connected to VDD
JP4 connected to GND
0
1
Boot from the system memory
JP1 connected to VDD
JP4 connected to VDD
1
1
Boot from SRAM
(1)It is recommended that JP4 selects GND when the PB2 function is not used.
3.5
External clock source
3.5.1 HSE clock source
The 8 MHz crystal on the board is used as HSE clock source
3.5.2 LSE clock source
There are three hardware modes to set the external low-speed clock sources:
On-board crystal (default setting):
The 32.768 kHz crystal on the board is used as LSE clock source. The hardware setting must
be: R6 and R7 ON, R5 and R8 OFF.
Oscillator from external PC14:
External oscillator is injected from the pin-3 of J2. The hardware setting must be: R5 and R8
ON, R6 and R7 OFF.
LSE not used:
PC14 and PC15 are used as GPIO. The hardware settings must be: R5 and R8 ON, R6 and
R7 OFF.
Summary of Contents for AT-START-F407
Page 17: ...AT START F407 User Manual 2020 11 20 17 Rev 1 20 4 Schematic Figure 4 Schematic AT Link EZ...
Page 18: ...AT START F407 User Manual 2020 11 20 18 Rev 1 20 Figure 5 Schematic microcontroller...
Page 20: ...AT START F407 User Manual 2020 11 20 20 Rev 1 20 Figure 7 Schematic extension connectors...
