Posted on November 06, 2016 at 14:35
I found the answer to my issue. It turns out there is a setting for the ''Polling interval''. By default it is set to 32ms. It is found in usbd_customhid.c:
/* USB CUSTOM_HID device Configuration Descriptor */
__ALIGN_BEGIN
static
uint8_t USBD_CUSTOM_HID_CfgDesc[USB_CUSTOM_HID_CONFIG_DESC_SIZ] __ALIGN_END =
{
0x09,
/* bLength: Configuration Descriptor size */
USB_DESC_TYPE_CONFIGURATION,
/* bDescriptorType: Configuration */
USB_CUSTOM_HID_CONFIG_DESC_SIZ,
/* wTotalLength: Bytes returned */
0x00,
0x01,
/*bNumInterfaces: 1 interface*/
0x01,
/*bConfigurationValue: Configuration value*/
0x00,
/*iConfiguration: Index of string descriptor describing
the configuration*/
0xC0,
/*bmAttributes: bus powered */
0x32,
/*MaxPower 100 mA: this current is used for detecting Vbus*/
/************** Descriptor of CUSTOM HID interface ****************/
/* 09 */
0x09,
/*bLength: Interface Descriptor size*/
USB_DESC_TYPE_INTERFACE,
/*bDescriptorType: Interface descriptor type*/
0x00,
/*bInterfaceNumber: Number of Interface*/
0x00,
/*bAlternateSetting: Alternate setting*/
0x02,
/*bNumEndpoints*/
0x03,
/*bInterfaceClass: CUSTOM_HID*/
0x00,
/*bInterfaceSubClass : 1=BOOT, 0=no boot*/
0x00,
/*nInterfaceProtocol : 0=none, 1=keyboard, 2=mouse*/
0,
/*iInterface: Index of string descriptor*/
/******************** Descriptor of CUSTOM_HID *************************/
/* 18 */
0x09,
/*bLength: CUSTOM_HID Descriptor size*/
CUSTOM_HID_DESCRIPTOR_TYPE,
/*bDescriptorType: CUSTOM_HID*/
0x11,
/*bCUSTOM_HIDUSTOM_HID: CUSTOM_HID Class Spec release number*/
0x01,
0x00,
/*bCountryCode: Hardware target country*/
0x01,
/*bNumDescriptors: Number of CUSTOM_HID class descriptors to follow*/
0x22,
/*bDescriptorType*/
USBD_CUSTOM_HID_REPORT_DESC_SIZE,
/*wItemLength: Total length of Report descriptor*/
0x00,
/******************** Descriptor of Custom HID endpoints ********************/
/* 27 */
0x07,
/*bLength: Endpoint Descriptor size*/
USB_DESC_TYPE_ENDPOINT,
/*bDescriptorType:*/
CUSTOM_HID_EPIN_ADDR,
/*bEndpointAddress: Endpoint Address (IN)*/
0x03,
/*bmAttributes: Interrupt endpoint*/
CUSTOM_HID_EPIN_SIZE,
/*wMaxPacketSize: 2 Byte max */
0x00,
0x01,
/*bInterval: Polling Interval (20 ms)*/
//CHANGED FROM 0x20
/* 34 */
0x07,
/* bLength: Endpoint Descriptor size */
USB_DESC_TYPE_ENDPOINT,
/* bDescriptorType: */
CUSTOM_HID_EPOUT_ADDR,
/*bEndpointAddress: Endpoint Address (OUT)*/
0x03,
/* bmAttributes: Interrupt endpoint */
CUSTOM_HID_EPOUT_SIZE,
/* wMaxPacketSize: 2 Bytes max */
0x00,
0x01,
/* bInterval: Polling Interval (20 ms) */
//CHANGED FROM 0x20
/* 41 */
} ;
The ''bInterval'' field can be changed to 0x01, after which I saw 1000 packets per second as expected.
That still leaves the question for me: is it normal to change this setting? It seems a bit strange to have to change the driver code instead of just the values configured in user code.
Thanks!
