UM1018 datasheet(9/42 Pages) STMICROELECTRONICS

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UM01018

Hardware and layout

Doc ID 18141 Rev 2

9/42

2.3

Clock source

Two clock sources are available on the STM32L152-EVAL evaluation board for the

STM32L152VBT6 and embedded RTC.

●

X1, 32 KHz crystal for embedded RTC

●

X2, 8 MHz crystal with socket for the STM32L152VBT6 microcontroller, it can be

removed from the socket when an internal RC clock is used.

2.4

Reset source

The reset signal of the STM32L152-EVAL evaluation board is low active and the reset

sources include:

●

Reset button B1

●

Debugging Tools from JTAG connector CN9 and trace connector CN8

●

Daughterboard from CN7

●

Embedded ST-LINK/V2

●

RS-232 connector CN2 for ISP

Note:

Jumper JP9 must be changed for RESET. This is handled by pin8 of the RS-232 connector

CN2 (CTS signal), refer to Section 2.9 for details.

Table 2.

32 KHz crystal X1 related solder bridges

Solder bridge

Description

SB1

PC14 is connected to 32 KHz crystal when SB1 is open (default setting).

PC14 is connected to extension connector CN6 when SB1 is closed. In such

case R37 must be removed to avoid disturbance due to the 32 KHz quartz.

SB4

PC15 is connected to 32 KHz crystal when SB4 is open (default setting).

PC15 is connected to extension connector CN6 when SB4 is closed. In such

case R38 must be removed to avoid disturbance due to the 32 KHz quartz.

Table 3.

8 MHz crystal X2 related solder bridges

Solder bridge

Description

SB2

PH1 is connected to 8 MHz crystal when SB2 is open (default setting).

PH1 is connected to extension connector CN7 when SB2 is closed. In such case

R39 must be removed to avoid disturbance due to the 8 MHz quartz.

SB3

PH0 is connected to 8 MHz crystal when SB3 is open (default setting).

PH1 is connected to extension connector CN7 when SB3 is closed. In such case

C30 and X2 must be removed.

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