It has been more than two years since I bought a Pinecil soldering iron and wrote about soldering the breakout board and accessing the UART . I’ve been doing more work with the Pinecil as of late following the addition of upstream support for the Bouffalo Lab BL706 MCU in Zephyr (big shout out to @VynDragon , @will-tm , @josuah , and everyone else who has been contributing to the upstream Bouffalo Lab efforts!). While accessing the UART is helpful for viewing logs, debug access is critical when chasing down early system initialization and driver issues. While there are a variety of JTAG probes on the market, I typically reach for my JLink due to its broad compatibilty and robust tooling. In order to connect a JLink to the Pinecil, the breakout board described in my previous posts is required. It includes a 10-pin header for JTAG breakout with a 3v3 reference pin, 4 GND pins, and the standard JTAG signals.…