Mekhi 发表于 August 6, 2020
Probably, when PC8 (USBDPU) of U7 outputs low level, give STM_USBDP a 1.5k pull-up resistor, otherwise it is left floating.
Kaya 发表于 August 6, 2020
I simulated it with Multisim, but I still don’t understand STM_USBDP and STM_USBDM, which are obviously a set of differential USB signals. Why do I need this USBDPU to control the floating or pull-up?
Javon 发表于 August 6, 2020
Plug in the device and self-check the start of the handshake between the host and the device. And signal conversion from 3.3V to 5V.
