The traditional JLINK is large in size and has many pins, and the unofficial version we use often loses firmware. Many problems have been bothering me. After a lot of tossing, I finally found the correct solution: jlinkob, a debugger with only three lines, except that it cannot Detect the voltage of the target board (it's useless), the rest are advantages: small size (only the size of a u disk), less pins (only two pins), data cable and android mobile phone common (everywhere Yes), automatic upgrade, no firmware loss (it has been used for several years, never lost firmware), and more advantages to explore by yourself!
Jlink-OB is an on-board Jlink debugging solution customized by SEGGER for development boards. It is usually designed on evaluation boards ("on-boards") of major companies, which is why the suffix "OB" is used. The Jlink-OB emulator has the USB communication function to communicate with the PC, and the other end communicates with the supported device through SWD to complete the debugging and downloading task. Except that the target board voltage cannot be tested, this Jlink has almost the same function as the official version (the speed is limited to 4MHz).