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%(qi-html-body-top)sThe regular programming fixture looks like this when all the signals shown in http://downloads.qi-hardware.com/people/werner/anelok/tmp/mk3-quick/quick.pdf are connected: http://downloads.qi-hardware.com/people/werner/anelok/tmp/mk3-quick/quick-complete.jpg The two unpopulated holes are for supplying battery and USB power, which are intended for production testing (or for the power-only fixture) but are not used with the Ben as programmer. In this configuration, 3V3 is provided by the memory card interface of the Ben. This interface has a little flaw: there is a FET to switch power to the memory card and there is a 10 uF buffer capacitor. [1] Unfortunately, this capacitor is on the "outside", so when supplying power to the memory card, the Ben has to charge the capacitor, plus any capacitance on the card. This causes a drop of the internal 3.3 V rail of the Ben, which has only a bit more than 10 uF of buffer capacitors of its own. When using this to supply the 3V3 rail of Anelok, which has a total of at least 30.4 uF [2], the resulting massive voltage drop immediately hangs the Ben. This could probably be solved by not powering the internal 3.3 V rail of Anelok directly, but feeding power to one of the regulators, either USB (1.1 uF input capacitance) or battery (10 uF), instead. However, in the case of USB, the resulting 3V3 rail would then be at only about 3.0 V, which is okay for the MCUs, but borderline for the OLED panel. And in the case of battery power, this would require the whole circuit to be present and operational, which is something we can't take for granted during development and testing. Fortunately, there is another option: instead of taking power from the Ben, we can use a lab power supply instead. This requires a variant of the regular programming fixture, using the same plastic parts, but wired like this: http://downloads.qi-hardware.com/people/werner/anelok/tmp/mk3-quick/quick-extpwr-bottom.jpg For good measure I added a 22 uF capacitor on the power connector. And this is what it all looks like in operation, complete with clamp so that I don't have to push the PCB into the fixture and have my hands free for typing: http://downloads.qi-hardware.com/people/werner/anelok/tmp/mk3-quick/quick-extpwr-top.jpg With all this in place, I was finally able to reach the third MCU, of the BTLE radio: root at BenNanoNote:~# ./nrf Cortex M0 AP #1 ID 0x00000000 (???) AP #0 ID 0x04770021 (AHB-AP) HWID 0x0084 (QFAC) Flash 1024 bytes * 256 pages = 262144 bytes RAM 8192 bytes * 4 blocks = 32768 bytes UID 5b85d400-5bba8e43 MAC 36:e4:e5:9d:97:f1 (random) This is the last major component I had to verify. There are still a few things missing, but the remaining bits are either known to work (e.g., the OLED), or can be bypassed if they don't (e.g., the load switch for display and card, which is hard to solder under the best of circumstances, and I made it even harder by placing it too close to the card header.) - Werner [1] Page 5 of http://en.qi-hardware.com/w/images/9/9c/Lb60_schematic.pdf [2] http://downloads.qi-hardware.com/people/werner/anelok/tmp/power-tree-20170405.pdf