Hello,
I have a question regarding Orange Cube. Can somebody tell me in what way an information about USB voltage is valid or not valid would be used on the application side?PSM board mounted on carrier board detects if voltage on USB line is within allowed voltage range - if it is, GPIO_nVDD_USB_VALID connected to the PC0 on STM mCU goes on logical “zero”, otherwise would stay on logical “one”.
/boards/cubepilot/cubeorange/src/board_config.h
#define GPIO_nVDD_USB_VALID /* PC0 */ (GPIO_INPUT|GPIO_PULLUP|GPIO_PORTC|GPIO_PIN0) // VBUS_VALID
#define BOARD_ADC_USB_VALID (!px4_arch_gpioread(GPIO_nVDD_USB_VALID))
Info about validity status of USB power line is then used in /src/drivers/board_adc/ADC.cpp file
#if defined(BOARD_ADC_USB_VALID)
system_power.usb_valid = BOARD_ADC_USB_VALID;
#else
/* If not provided then use connected */
system_power.usb_valid = system_power.usb_connected;
#endif
I’m not planning to supply Cube and external sensors from USB directly, since USB is not reliable source of the power for such power demand I would have. I would like to connect +5V from USB line only to VBUS of the STM microcontroller (STM would be able to start with enumeration when USB cable would be connected) and I would like to connect GPIO_nVDD_USB_VALID (PC0) pin via pull-up resistor to 3.3 V, so PX4 code would always have information that Cube is not supplied from USB. What would be disadvantage of such implementation?
Thanks!