Hardware overview

UM2461

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UM2461 Rev 2

Figure 10. Crystal oscillator (default configuration)

The jumpers SB1, SB2 and SB3 allow enabling further input clock as described in Table 3.

2.5

Reset circuit

Figure 11

shows the reset circuit; it generates a sharp signal to reset the microcontroller

when the pushbutton SW1 is pushed.

SW1 triggers the STM6315RB-2.63V and it generates reset pulse (active low signal); D2 is

turned on when the reset pulse is generated. The solder jumper SB16 allows to disconnect

PORST and NRST signals (in the default configuration it is closed).

The internal reset generator can be disabled and the reset signal can be provided by an

external source connected to CN6 pin3; to implement this configuration SB15 should be

removed.

Table 3. Crystal oscillator - jumper configuration

SB1

SB2

SB3

Crystal (40MHz)

Open

Close

Open

Ext Clock

Close

Open

Open