Page 49 of the USB 2.0 Spec from usb.org says
"4.7.3 Interrupt Transfers
A limited-latency transfer to or from a device is referred to as interrupt data. Such data may be presented for transfer by a device at any time and is delivered by the USB at a rate no slower than is specified by the device. Interrupt data typically consists of event notification, characters, or coordinates that are organized as one or more bytes. An example of interrupt data is the coordinates from a pointing device. Although an explicit timing rate is not required, interactive data may have response time bounds that the USB must support."
Page 195 of the Philips LPC214X UM says.
“Fully compliant with USB 2.0 Full Speed specification” and “Supports Control, Bulk, Interrupt and Isochronous endpoints.”
Page 197 of the Philips LPC214X UM says.
“USB is a host controlled protocol, i.e., irrespective of whether the data transfer is from the host to the device or device to the host, transfer sequence is always initiated by the host. During data transfer from device to the host, the host sends an IN token to the device, following which the device responds with the data.”
My question:
How can I send an unsolicited message to the host? Is there a code example of this available anywhere? After enumeration has occurred, I would like to be able to 1) have the ARM interrupt on change of input status, and 2) send a USB message to the host. Page 197 of LPC214X spec seems to indicate that this is not possible. Can someone please elaborate on this?