A breakout board for JTAG interface for ARM devices. You plug a JTAG probe at one end, and get pins to connect to your board. Available headers for probes are for:

  • SEGGER J-Link (and seemingly original ST-Link),

  • Chinese clone of ST-Link (in metal case),

  • Chinese clone of ST-Link flashed with BlackMagic Debug Probe.

  • MCUs connect via either a 2.54mm header or a 1.27mm header. The pinout is GND-3V3-CLK-DIO-RST.

Link to PCB project: https://oshwlab.com/positron96/swd-breakout.

The schematic is really simple and mostly contains connectors, headers and jumpers. The highlight of the PCB is colorful silkscreen, more on that in the following section.

Colorful silkscreen

The PCB is also a test of a colorful silkscreen from JLCPCB. The fabhouse sometimes gives coupons for new products, and I happened to have one. The results can be seen of the photos (unfortunately, the phone blurs the picture heavily).

All in all, the PCBs look really impressive. White areas are glossy (it’s soldermask), the rest is matte and has rough texture to the touch. When ordering colorful silkscreen, JLCPCB upgrades the order to ENIG coating (for free), so the pads are yellow. Near PCB edges and metal areas there is a white border of a fraction of a millimeter. In dark areas contrast is low and shades are rather indistinctive (as seen near OSHW logo).

I can imagine also using the technology outside of PCB manufacturing purposes.

Photos