I was developing my lcd application under discoveryf4 (see photo) and everthing works fine.
I decided to develop my custom board, and use discovery to flash and debug my stm32f407vgt6 mounted on my custom board.
In order to make this, jumper on CN3, jumper on JP1, bridge on SB11 of discovey has been removed.
After connected my custom cable (gnd, swdio, swclk, nrst signals) SURPRIIIISEEEE!!!!! everthing works at the first attempt (successfully loaded blink_led_firmware).
So I decide remove flying cables of lcd and, SURPRISE, nothing works anymore.
I can't connect via swd to my custom board. Neither using st-link utility.
Vdd is stable 3.3V.
Voltage on VCAP is 1.26Volts.
Xtal is this . Replaced with xtal removed from other discovery board. Replaced with other 10mhz xtal.
Tried 0 ohm, 220 ohm, 1kOhm on rcc_osc_out pin,
Capacitors on Xtal are 2x20pf COG 0805. Replaced with capacitor removed from other discovery board.
Soldered new pcb with new components.
SWDIO and SWCLK signals on discovery are good.
The only bad design (I see) is xtal analog gnd sorrounded in digital gnd.
My xscope alway find 0v on rcc_osc pins.
I've already read many posts about not working hse but they were not helpfully for me.
I'm having this problem by 4 days, please give me some ideas.