4.2 Virtual COM Port
The virtual COM port is a connection to a UART of the target EFM8, and allows serial data to be sent and received from the device. The
on-board debugger presents this as a virtual COM port on the host computer that shows up when the USB cable is inserted. Alterna-
tively, the VCOM port can also be used through the Mini Simplicity Connector with an external WSTK.
Data is transferred between the host computer and the debugger through the USB connection, which emulates a serial port using the
USB Communication Device Class (CDC). From the debugger, the data is passed on to the target device through a physical UART
connection.
The serial format is 115200 bps, 8 bits, no parity, and 1 stop bit.
Using the VCOM port through the Mini Simplicity Connector with an external WSTK works in a similar way, but requires that the on-
board debugger is unplugged. The board controller on the WSTK then makes the data available over USB (CDC) or an IP socket.
Note:
Changing the baud rate for the COM port on the PC side does not influence the UART baud rate between the debugger and the
target device.
4.3 Mini Simplicity Connector
The Mini Simplicity connector is a 10-pin 1.27 mm pitch connector that gives access to advanced debugging features using an external
debugger. Debugging with an external debugger such as a Silicon Labs Starter Kit (STK) or Wireless Starter Kit (WSTK) allows:
• Debugging of the target device through the C2 interface
• Communication using the VCOM port
• Advanced Energy Monitor
Please note that the Mini Simplicity Connector
cannot
be used at the same time as the on-board debugger is active (debug USB cable
is plugged in). The "Power Source" slide switch must furthermore be placed in the "DBG USB" position, as the Mini Simplicity connector
injects a voltage into the target EFM8 voltage domain. For information on how to correctly connect to the kit, see
Figure 4.1 Thunder-
board EFM8UB3 Debugging Possibilities on page 13
. The recommended way to power the board when using the Mini Simplicity Con-
nector is to use the AEM voltage supply of the STK or WSTK. Power-cycling of the board, if necessary, can easily be done by flipping
the power switch on the WSTK to "BAT" and back to "AEM".
UG308: Thunderboard EFM8UB3 User's Guide
Debugging
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