Clock Source; Table 3. 25 Mhz Crystal X1 Related Solder Bridges; Table 4. 32 Khz Crystal X2 Related Solder Bridges - ST STM32F779I-EVAL User Manual

UM2036
The LED LD10 is lit when the STM32F779I-EVAL evaluation board is powered by the 5 V
correctly.
To avoid the impact of USB PHY and Ethernet PHY and get precise results of current
consumption on JP2, the following cautions must be taken into account:
1. Configure Ethernet PHY into Power Down Mode by setting low level of IO_Expander
(EXP_IO1)
2. Configure USB HS PHY into Low-power mode (Register address = 04, bit 6 in USB
PHY).
6.3

Clock source

Five clock sources are available on the STM32F779I-EVAL board:
•
X1, 25 MHz crystal for the HSE of the STM32F779NI
• X2, 32 KHz crystal for embedded RTC of the STM32F779NI
•
X3, 24 MHz oscillator for camera module (Default on camera daughterboard)
• X4, 25 MHz crystal with socket for Ethernet PHY
•
X5, 24 MHz crystal for USB OTG2 HS PHY
Jumper
SB40
SB41
Solder
bridge
SB38
SB39
Note: Jumper JP12 for Ethernet clock refers to

Table 3. 25 MHz crystal X1 related solder bridges

PH0 is connected to 25 MHz crystal when SB40 is open.
(Default setting)
PH0 is connected to extension connector CN5 when SB40 is closed. In such case
C23, X1 must be removed to avoid disturbance due to the 25 MHz quartz.
PH1 is connected to 25 MHz crystal when SB41 is open.
(Default setting)
PH1 is connected to extension connector CN5 when SB41 is closed. In such case
R20 must be removed to avoid disturbance due to the 25 MHz quartz.

Table 4. 32 KHz crystal X2 related solder bridges

PC14 is connected to 32 KHz crystal when SB38 is open.
(Default setting)
PC14 is connected to extension connector CN6 when SB38 is closed. In such case
R23 must be removed to avoid disturbance due to the 32 Khz quartz.
PC15 is connected to 32 KHz crystal when SB39 is open.
(Default setting)
PC15 is connected to extension connector CN6 when SB39 is closed. In such case
R22 must be removed to avoid disturbance due to the 32 Khz quartz.
DocID029088 Rev 3
Hardware layout and configuration
Description
Description
Section 6.12: Ethernet.
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