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nrf51 wont run without debugger

Jim Peschke

Have an nrf51 board design that doesn't want to run without a debugger. When programmed, the debugger can run the board. When the debugger is removed, the board does not seem to run at all.

The SWDCLK line has a 12k pulldown. The SWDIO line has a 12k pullup. I suspect these pins, especially SWDIO, might be the culprit. Sometimes I can get the board running by touching SWDIO with an oscilloscope probe.

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    Yes, ask the SW developer about that! All the BLE examples in the SDK is configured to use external 32 kHZ crystal, so it's crucial to configure the SoftDevice to use the RC oscillator on boards that don’t have an external 32 kHz crystal. On the newest reference design a 1K ohm pulldown on SWDCLK is added, anything other than that is a bit “overkill”. No need for external pullup on SWDIO.

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    Yes, ask the SW developer about that! All the BLE examples in the SDK is configured to use external 32 kHZ crystal, so it's crucial to configure the SoftDevice to use the RC oscillator on boards that don’t have an external 32 kHz crystal. On the newest reference design a 1K ohm pulldown on SWDCLK is added, anything other than that is a bit “overkill”. No need for external pullup on SWDIO.

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