4.1 On-board Debugger
The on-board debugger is a SEGGER J-Link debugger running on an EFM32 Giant Gecko. The debugger is directly connected to the
debug and VCOM pins of the target ZGM230S.
When the debug USB cable is inserted, the on-board debugger is automatically activated, and takes control of the debug and VCOM
interfaces. This means that debug and communication will
not
work with an external debugger connected at the same time. The on-
board LDO is also activated, providing power to the board.
When the USB cable is removed, the board might still be running on battery power, as described in section
. In this
case, the on-board debugger goes into a very low power shutoff mode (EM4S), consuming about 80 nA. This means that battery life-
time will not be affected too much by the on-board debugger power consumption. Since the I/O voltage rail of the debugger remains
powered in the battery-operated mode, the pins connected to the debug and VCOM interfaces maintain proper isolation and prevent
leakage currents.
4.2 External Debugger
A Wireless mainboard from Silicon Labs can be connected to the Mini Simplicity Connector and used for debugging instead of the on-
board debugger. For instruction on using the mainboard for debugging, see
AN958: Debugging and Programming Interfaces for Cus-
. Note that the Wireless STK Mainboard (BRD4001A) requires a BRD8010A STK/WSTK Debug Adapter to get access to
the Mini Simplicity Connector. Debugging with an external Wireless mainboard gives access to the following debugging features:
• Debugging of the target device through SWD
• Communication using the VCOM port
• Packet Trace Interface (for wireless devices only)
• Advanced Energy Monitor
Note that the Mini Simplicity Connector
cannot
be used at the same time that the on-board debugger is active (USB cable is plugged
in). For information on how to correctly connect to the kit, see
Figure 4.1 ZGM230S Dev Kit Debugging Possibilities on page 21
.
Powering the board when using the Mini Simplicity Connector with a Wireless mainboard can be done using the AEM voltage supply of
the Wireless mainboard. When doing this, remove both the USB cable and the coin cell battery from the ZGM230S Dev Kit before con-
necting the Wireless mainboard to the Mini Simplicity Connector. The power switch on the Wireless mainboard should be set in "AEM".
Power-cycling of the board, if necessary, is easily done by flipping the power switch on the Wireless to "BAT" and back to "AEM", as-
suming a battery is not inserted in the Wireless mainboard.
It is possible to have the ZGM230S Dev Kit powered by a battery, and still use the Mini Simplicity Connector with a Wireless mainboard
for debugging and communication. In this case, the power switch on the Wireless mainboard must be set to the "BAT" position and the
coin cell battery on the Wireless mainboard must be removed. In this case, level shifters on the Wireless mainboard itself take care of
interfacing to different voltage levels on the ZGM230S Dev Kit. Connecting the board to an external debugger in other ways than those
described above might create power conflicts, compromise the ability to monitor power consumption, and hazardously feed power back
to the on-board battery.
Important:
Always remove the battery if you are not sure whether the external debugger is sourcing voltage to ZGM230S Dev Kit.
4.3 Virtual COM Port
The virtual COM port (VCOM) is a connection to a UART on the ZGM230S and allows serial data to be sent and received from the
device. The on-board debugger presents this connection as a virtual COM port on the host computer that shows up when the USB
cable is inserted.
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 by default.
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. However, it is possible to change the VCOM baud rate through the kits' Admin Console available through Simplicity Stu-
dio.
Alternatively, the VCOM port can also be used through the Mini Simplicity Connector with an external Wireless mainboard. Using the
VCOM port through the Mini Simplicity Connector with an external Wireless mainboard works in a similar way, but requires that the
USB cable to the on-board debugger is unplugged. The board controller on the Wireless mainboard then makes the data available over
USB (CDC) or an IP socket. Flow control is not available over the Mini Simplicity Connector.
UG532: ZGM230S Dev Kit User's Guide
Debugging
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