Laird Lyra S, Руководство пользователя

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The kit is powered by the debug USB cable as illustrated in the figure below.
Figure 3: Lyra S DVK power diagram
The 5 volt power net on the USB bus is regulated down to 3.3 V using an LDO (low-dropout regulator). An automatic isolation
circuit isolates the LDO when the USB cable is not plugged in.
Power can be injected externally on the VMCU net if the USB cable is removed and no other power sources are present on
the kit. Failure to follow this guideline can cause power conflicts and damage the LDO.
The Lyra S can be reset by a few different sources:
▪
A user pressing the RESET button.
▪
The on-board debugger pulling the #RESET pin low.
The kit has one user push button marked BTN0 and one LED marked LED0 that are each connected to a GPIO on the
Lyra S. The button is connected to pin PA06 and it is debounced by an RC filter with a time constant of 1 ms. The logic state
of the button is high while the button is not being pressed, and low when the button is pressed. The LED is configurable in
firmware for
user’s application. See
BOOT pin (PA06) and BUTTON 0 (silkscreen BTN0) usage information.
Figure 4: Lyra S DVK Button and LED