UM0240 datasheet(22/39 Pages) STMICROELECTRONICS

Numer części	UM0240

Szczegółowy opis	ST Industrial Communication Board - EVALCOMMBOARD

PDF	39 Pages

Scroll/Zoom	100%

Producent	STMICROELECTRONICS [STMicroelectronics]

Strona internetowa	http://www.st.com

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22 / 39 page

Switches

UM0240

22/39

Switches

The board is equipped with five switches: a microcontroller reset switch (RES), and four

general purpose switches (SW1, SW2, SW3 and SW4).

The RES switch is directly connected with the microcontroller RESET pin used to perform a

hardware reset of the MCU. In order to guarantee the correct timing for the RESET negative

pulse, an RC network is connected to the switch.

General purpose switches are connected to the AD converter embedded on the

microcontroller (Channel 0 is used) through a resistor divider network.

Figure 8.

General purpose switches

Each time a key is pressed, the corresponding resistor divider is activated. Then the voltage

read by the ADC tells the microcontroller which button has been pressed.

Figure 9.

General purpose switches voltages and decisions level

UM0240 Arkusz danych(PDF) 22 Page - STMicroelectronics