I'm developing the PCB schematic for a system using the nRF52 and have some questions on the SWD programming interface.
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It seems that I only need 4 pins for the Segger J-Link Base (VTREF/SWDIO/SWDCLK/GND), correct?
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P0.21 is labeled as a RESET pin also; does the SWD programmer require access to this? If it is optional, what are the benefits to having it connected, and how do I enable the RESET functionality?
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Since I don't need all 20 pins, I plan on using an adapter board such as the J-LINK 9-PIN CORTEX-M ADAPTER. But I also found the ARM-JTAG-20-10 which is 5x cheaper. The schematics seem the same for both, so can I use the ARM-JTAG-20-10 with the Segger J-Link Base? Why is there such a huge price difference if they are the same?
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Are there any low cost programmers that support 1.8V (I'll have the nRF52 powered directly by a 1.8V supply)?