Clock Source; Table 3. Low Voltage Limitation; Table 4. 32 Khz Crystal X1 Related Solder Bridges; Table 5. 8Mhz Crystal X2 Related Solder Bridges - ST STM32091C-EVAL User Manual

UM1817
Peripheral
Audio amplifier
Microphone amplifier
CAN
Smart Card
CAUTION:
1. JP8 and JP12 are not allowed to be opened; otherwise STM32F091VCT6 would be
damaged due to lacking of power supply on its power pins.
2. Risk of explosion if battery is replaced by an incorrect type. Dispose of used batteries
according to the instructions.
2.4

Clock Source

Two clock sources are available on STM32091C-EVAL evaluation board for
STM32F091VCT6 and RTC embedded.
•
X1, 32KHz Crystal for embedded RTC
•
X2, 8MHz Crystal with socket for STM32F091VCT6 Microcontroller, it can be removed
from socket when internal RC clock is used.
Jumper
SB11
SB12
Jumper
SB13

Table 3. Low voltage limitation

Component
U18
U15
CN5
CN19

Table 4. 32 KHz Crystal X1 related Solder Bridges

PC14 is connected to 32KHz crystal when SB11 is open.
(Default setting)
PC14 is connected to extension connector CN6 when SB11 is closed. In such case
R54 must be removed to avoid disturbance due to the 32Khz quartz
PC15 is connected to 32KHz crystal when SB12 is open.
(Default setting)
PC15 is connected to extension connector CN6 when SB12 is closed. In such case
R55 must be removed to avoid disturbance due to the 32Khz quartz

Table 5. 8MHz Crystal X2 related Solder Bridges

PF0 is connected to 8MHz crystal when SB13 is open.
(Default setting)
PF0 is connected to extension connector CN7 when SB13 is closed. In such case
C18 and X2 must be removed.
DocID026902 Rev 2
Hardware Layout and configuration
IO name
Audio input
Audio output
CAN
USART2
Description
Description
Low voltage limitation
2.2 V (VDDA)
2.7 V (VDDA)
3 V (VDDIO2)
2.7 V (VDD)
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