Gettio/Barrio

[kategray]

If you are using these on Linux I'd love to see your EVHZ output/know why these work out of the box :)

What would you like to know?

[geefr]

Well, the output from evhz and any info on how those devices manage 1Khz polling out of the box (By default Linux polls HID devices at 125Hz, so what's special here?)

Alternatively it's an open invitation to update the docs to account for those, as they're well recommended in general

[kategray]

They are polled at that speed because I request it.

/*********************************************************************
* Device Descriptors
*********************************************************************/
const uint8 CYCODE USBFS_DEVICE0_DESCR[18u] = {
/* Descriptor Length                       */ 0x12u,
/* DescriptorType: DEVICE                  */ 0x01u,
/* bcdUSB (ver 2.0)                        */ 0x00u, 0x02u,
/* bDeviceClass                            */ 0x00u,
/* bDeviceSubClass                         */ 0x00u,
/* bDeviceProtocol                         */ 0x00u,
/* bMaxPacketSize0                         */ 0x08u,
/* idVendor                                */ 0xD0u, 0x16u,
/* idProduct                               */ 0x02u, 0x0Du,
/* bcdDevice                               */ 0x00u, 0x03u,
/* iManufacturer                           */ 0x01u,
/* iProduct                                */ 0x02u,
/* iSerialNumber                           */ 0x80u,
/* bNumConfigurations                      */ 0x01u
};
/*********************************************************************
* Config Descriptor  
*********************************************************************/
const uint8 CYCODE USBFS_DEVICE0_CONFIGURATION0_DESCR[34u] = {
/*  Config Descriptor Length               */ 0x09u,
/*  DescriptorType: CONFIG                 */ 0x02u,
/*  wTotalLength                           */ 0x22u, 0x00u,
/*  bNumInterfaces                         */ 0x01u,
/*  bConfigurationValue                    */ 0x01u,
/*  iConfiguration                         */ 0x03u,
/*  bmAttributes                           */ 0x80u,
/*  bMaxPower                              */ 0xFAu,
/*********************************************************************
* Interface Descriptor
*********************************************************************/
/*  Interface Descriptor Length            */ 0x09u,
/*  DescriptorType: INTERFACE              */ 0x04u,
/*  bInterfaceNumber                       */ 0x00u,
/*  bAlternateSetting                      */ 0x00u,
/*  bNumEndpoints                          */ 0x01u,
/*  bInterfaceClass                        */ 0x03u,
/*  bInterfaceSubClass                     */ 0x00u,
/*  bInterfaceProtocol                     */ 0x00u,
/*  iInterface                             */ 0x00u,
/*********************************************************************
* HID Class Descriptor
*********************************************************************/
/*  HID Class Descriptor Length            */ 0x09u,
/*  DescriptorType: HID_CLASS              */ 0x21u,
/*  bcdHID                                 */ 0x11u, 0x01u,
/*  bCountryCode                           */ 0x21u,
/*  bNumDescriptors                        */ 0x01u,
/*  bDescriptorType                        */ 0x22u,
/*  wDescriptorLength (LSB)                */ USBFS_HID_RPT_1_SIZE_LSB,
/*  wDescriptorLength (MSB)                */ USBFS_HID_RPT_1_SIZE_MSB,
/*********************************************************************
* Endpoint Descriptor
*********************************************************************/
/*  Endpoint Descriptor Length             */ 0x07u,
/*  DescriptorType: ENDPOINT               */ 0x05u,
/*  bEndpointAddress                       */ 0x81u,
/*  bmAttributes                           */ 0x03u,
/*  wMaxPacketSize                         */ 0x01u, 0x00u,
/*  bInterval                              */ 0x01u
};

The USB documentation for windows (which I'm currently using for reference) reads:

bInterval

The bInterval value contains the polling interval for interrupt and isochronous endpoints. For other types of endpoint, this value should be ignored. This value reflects the device's configuration in firmware. Drivers cannot change it.

The polling interval, together with the speed of the device and the type of host controller, determine the frequency with which the driver should initiate an interrupt or an isochronous transfer. The value in bInterval does not represent a fixed amount of time. It is a relative value, and the actual polling frequency will also depend on whether the device and the USB host controller operate at low, full or high speed.

Value of bInterval	Polling Period (1-millisecond frames)	Interrupt	Isochronous
1	1	Supported.	Supported.

[kategray]

The cause may be that low speed devices are polled no faster than 8ms. The Ghett-IO and Barr-IO are Full Speed devices.

[kategray]

For low speed devices:

Value of bInterval	Polling Period (1-millisecond frames)	Interrupt
0 to 15	8	Supported.

[geefr]

Ah cool, I don't know much about USB specifically :P

So as long as the system's drivers respect that it should all 'just work', nice.

Thanks for the info, I'll update the docs when I get a minute.

[geefr]

Wiki to be updated shortly