ST Link updagrading manual:
Our Standard STLink USB only matches 4 pitch cable, there’s 2 different situation when use the STLink:
- If ESC connect to power, you can only connect the 4 ports: RST; SWDIO; GND; SWCLK
- If ESC do not connect power, then need to connect 5 ports: RST; SWDIO; GND; SWCLK; 3.3V
Below is the example that doesn’t downloaded firmware successfully because didn’t connect power and 3.3V for ESC.
Another reason for this situation: If only use 3.3V to power the ESC from STLink, this only suitable for small ESC, because big ESC requires high power consumption, 3.3V is not enough.