Describe the remote wake up feature of USB supported by Calliope 2 and configuration needed
Hi Rajenish,
1\Calliope 2 modules USB state behaviour is controlled by the following interfaces:
• Enumeration, Suspend, Resume notification from Host over D+/D-.
• Remote wake-up signalling to host over D+/D-.
• USB_EXT_VBUS_VLD input pin state from the host.
• USB_READY output pin state. The USB_READY pin is triggered when the UE has data to send on ECM or ACM.
2\To do remote wake up: The host can place the module’s USB interface into a suspended state by issuing standard USB suspend signaling over the D+ and D− lines. The interface can subsequently be reactivated using USB resume signaling on the same lines. Alternatively, the host can disconnect the module’s USB interface by pulling USB_EXT_VBUS_VLD to ground. The UE is also capable of initiating a remote wake-up through the D+ and D− lines.
To support native USB suspend and resume operation, the USB connection must remain enumerated by the host. In this mode, the integrity of both ACM and ECM interfaces is maintained.
Any data transmitted from the host to the Calliope 2 module via USB automatically resumes the interface and wakes the module from the suspended state. Likewise, when the Calliope 2 module has data or events that need to be communicated, it can issue a USB remote wake-up request to bring the host MCU out of its low-power state.