Can I use the USB Debug Adapter (UDA) to debug an EFM8 device on my custom PCB as well as to debug the EFM8 device present on the EFM8 Starter Kit (STK) (instead of the on-board J-Link adapter) in Simplicity Studio v4?
Yes, the Silicon Labs 8-bit USB Debug Adapter (UDA, Figure 1) can be used to debug an EFM8 device in Simplicity Studio v4, regardless of whether it is on a custom board or on a Silicon Labs EFM8 starter kit (i.e. the EFM8 present on the starter kit for evaluation purposes). Besides the requirement that the device be powered with correct hardware configuration (i.e. bypass capacitors, etc.), the only connections necessary for debugging in this case are C2D, C2CK, and GND.
The following image shows the correct connections to make to debug the EFM8 MCU present on the STK. Note that if the MCU is powered from the on-board debug USB (J-Link) connector, then the board controller may attempt to drive the target MCU C2 debug signals, creating contention with the USB Debug Adapter C2 signals. For this reason, it is safest to configure the STK debug to “OFF” mode (or to power the device from the coin cell battery or an external power supply, with the J-link USB connection disconnected).
The following image shows the correct/corresponding pins needed for use on the UDA:
C2D – pin 4
C2CK – pin 7
GND – pins 9, 2, or 3 (only one of these is necessary)
Finally, this is what it will look like when SS v4 is connected to the device using the UDA:
The process to connect to, program, and debug an EFM8 device on a custom board is analogous to the above discussion. You must simply ensure that the device is powered correctly as recommended for your device and provide a three pin header/connector (connected to C2D, C2CK, and GND) on your custom board similar to that shown on the EFM8 STK, which will serve as an attachment point for the UDA.