7.2 Push Buttons and LEDs
The Expansion Board contains two push buttons (marked BTN2 and BTN3 on the PCB) and two LEDs (LED2 and LED3 not marked
but placed correspondingly above the push button markings correspondingly). The push buttons and LEDs share the same two module
I/O pins. Each push button is connected to a LED through a transistor, allowing both I/O's to be used either as an input (for reading the
push button state) or as an output (to control the LED state on or off).
When configured as an input,
"0"
indicates that the button is being pressed and
"1"
that the push button is not being pressed. Likewise,
when configured as an output,
"0"
will turn the LED on and
"1"
will turn it off.
Pressing a push button will also light up the corresponding LED because the LED is controlled by the same line (state) regardless of
whether it is the Module or the push button that pulls the line low.
The push buttons are debounced by RC filters with a time constant of about 1 ms. Pressing the push button while having the pin config-
ured as an output in high state (
"1"
) will not cause damage, but will cause extra current to flow.
Figure 7.2 Location of Push Buttons and LEDs on the WSTK Mainboard
UG172: Wizard Gecko Wi-Fi® Module Wireless Starter Kit SLWSTK6120A User's Guide
Expansion Board
silabs.com
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