z-uno module stops working when USB is not connected
Posted: 29 Jun 2019 01:24
Hello together,
I have a problem with the z-uno module. I have connected the USB_DP, USB_DM and GND to a USB cable. The VCC andGND is connected to a 3.3V power supply (as depiced in the reference). Pin 13 is wired to a LED (including a fitting resistor). With this setup i can reach the module via USB.I can program it and I can my serial outputs via USB. The LED is flashing also. Everthing fine. But as soon as I disconnect the USB cable from my pc the scatch stops e.g the LED stops flashing, and it remains either on or off. When I plug in the USB cable again, the LED continous flashing. So what have I done wrong? Do I need any pull up/down resistors on the USB pins? For me it looks like the device ist trapped in a USB-ISR. Has anyone an idea? Or would it be possible to post a reference design?
Thank you for your answers
I have a problem with the z-uno module. I have connected the USB_DP, USB_DM and GND to a USB cable. The VCC andGND is connected to a 3.3V power supply (as depiced in the reference). Pin 13 is wired to a LED (including a fitting resistor). With this setup i can reach the module via USB.I can program it and I can my serial outputs via USB. The LED is flashing also. Everthing fine. But as soon as I disconnect the USB cable from my pc the scatch stops e.g the LED stops flashing, and it remains either on or off. When I plug in the USB cable again, the LED continous flashing. So what have I done wrong? Do I need any pull up/down resistors on the USB pins? For me it looks like the device ist trapped in a USB-ISR. Has anyone an idea? Or would it be possible to post a reference design?
Thank you for your answers