ComboDebug is a companion adapter for DAP42 debug probe, as well as standard ARM debuggers with 2.54mm 20-pin interface like J-Link and ST-Link.
DAP42 is a CMSIS-DAP compatible USB JTAG debug adapter for ARM Cortex-A and Cortex-M processors, based on the STM32F042K6 microcontroller.
This adapter provides a 1.27mm 10-pin modified Cortex Debug Connector with two of the original ground lines replaced with a serial port.
The serial port can be handled through the DAP42 host interface, or through an onboard USB to Serial adapter.
It also provides an external target reset button, and an offline programming trigger button for DAP42
This is open source hardware under 3-clause BSD license.