Necessity of the SWO Pin for Debug Purposes

[JOlso.12]

This question pertains to an STM32F413 target board I constructed.

I deliberately skinnied down my target's programing port to include only these barebones signals mentioned in the STLINK V3SET user manual:

• T_VCC
• T_SWCLK
• GND
• T_SWDIO
• T_NRST
• T_VCP_TX
• T_VCP_RX

The last two signals are to support the Virtual COM Port feature.

I can program my target board using the STLINK V3SET and STM32CUBEPROGRAMMER. However I cannot debug the board using STM32CUBEIDE.

Is the reason for this that I failed to implement the T_SWO signal between the STLINK and my target?

Thanks in advance for any feedback on this.

[TDK]

For barebones, only GND, SWDIO, and SWCLK are needed.

In any case, SWO is optional. You should be able to debug without it. Perhaps clarify what "I cannot debug the board" means. Why not?

[Tesla DeLorean]

Use SWO/PB3 here for its Debug Communications Channel equivalence to older ARM, basically a free UART for debug, diagnostics, telemetry, etc​

[S.Ma]

Gnd, swdio, swdclk, rst, tvcc should be enough to try to bringup the chip, even if it is in low power mode. However, check your chip has supply voltage. If using external clock, remove it to use internal one. Check reset pin level after power on and check boot pin level, check the swd bit rate if you use flying wires.

Swo is the poor's man vcp link, don't need both.