Lyra 24S Development Kit
User Guide
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10
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7.4.1
BOOT pin (PC07) and BUTTON 0 (silkscreen BTN0)
For the Lyra 24S module the BOOT pin is on PC07 (pin29). On the Lyra dev board BTN0 (Button0) is by default mapped to
the BOOT pin for easier utilisation.
The BOOT pin (PC07) is used to determine when execution of the bootloader is required. Upon reset, execution of the
bootloader begins. The state of the BOOT pin is read immediately upon start-up of the bootloader. If LOW (BTN0 pressed),
execution of the bootloader continues, facilitating firmware update via the UART. If the BOOT pin is HIGH (BTN0 not pressed),
the bootloader will stop execution and pass control to the main application firmware.
Please refer to respective DVK schematics and Serial DFU section of User Guide - Firmware Options and Upgrading - Lyra
Series for more information at:
www.lairdconnect.com/lyra24-series
7.5
On-board Debugger
The Lyra 24S Development Kit contains a microcontroller separate from the Lyra 24S that provides the user with an on- board
J-Link debugger through the USB Micro-B port. This microcontroller is referred to as the "on-board debugger
” and is not
programmable by the user. When the USB cable is removed, the on-board debugger goes into a very low power shutoff mode
(EM4S), consuming around 80 nA typically (EFM32GG12 data sheet number).
In addition to providing code download and debug features, the on-board debugger also presents a virtual COM port for
general purpose application serial data transfer. The Packet Trace Interface (PTI) is also supported which offers
invaluable debug information about transmitted and received packets in wireless links.
The figure below shows the connections between the target Lyra 24S device and the on-board debugger. See
Debugging for more details on debugging.
Figure 5: Lyra 24S DVK Debugger Connections
