There are cheap clones of simple CMSIS-DAP interfaces from China.

They support ARM SWD and UART I/O.

They are unable to reset the target which may be a problem in some circumstances.

NB Always wire the ground wire even if you think you do not need to.

# wch.cn WCH-Link CMSIS-DAP (clone)
SUBSYSTEMS=="usb",\
    ATTRS{idVendor}=="2a86",\
    ATTRS{idProduct}=="8011",\
    MODE:="0666"
KERNEL=="ttyACM*",\
    ATTRS{idVendor}=="2a86",\
    ATTRS{idProduct}=="8011",\
    GROUP:="dialout",\
    MODE:="0666"

Maple Mini

openocd -c "adapter driver cmsis-dap; cmsis_dap_vid_pid 0x2a86 0x8011" -c "adapter speed 500" -c "transport select swd" -f "target/stm32f1x.cfg"
Open On-Chip Debugger 0.12.0-rc2+dev-00012-g4e077fdda (2022-11-12-16:05)
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
adapter speed: 500 kHz

swd
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Info : CMSIS-DAP: SWD supported
Info : CMSIS-DAP: FW Version = 2.0.0
Info : CMSIS-DAP: Interface Initialised (SWD)
Info : SWCLK/TCK = 1 SWDIO/TMS = 1 TDI = 0 TDO = 0 nTRST = 0 nRESET = 1
Info : CMSIS-DAP: Interface ready
Info : clock speed 1000 kHz
Info : SWD DPIDR 0x1ba01477
Info : [stm32f1x.cpu] Cortex-M3 r1p1 processor detected
Info : [stm32f1x.cpu] target has 6 breakpoints, 4 watchpoints
Info : starting gdb server for stm32f1x.cpu on 3333
Info : Listening on port 3333 for gdb connections

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