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Re: [Libusb-devel] HID Access
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From: <ja...@t-...> - 2003-07-24 10:23:13
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> It would probably help to know what the device is. As an absolute minim=
um,
> seeing the HID descriptor (at least the Application) from lsusb or from
> your source code would help.
> libusb can probably do this, but hiddev might be a better bet. Out isn'=
t
> really good on Linux though - we'd need substantial design information =
to
> tell if that is going to be a big problem.
neither the application nor the source are finished yet and design=20
changes may required to fit the USB. The device is nothing ordinary but a=
=20
"cable" gateway from USB to several other interfaces. The purpose is uC f=
lash=20
programming (but this is low level and something completly diffrent from =
the=20
USB-DFU Class) RS232 Converters to USB are out of the shelf but there see=
ms=20
nothing to connect to ICC (from STM), BDM (from Motorola) and OCDS what i=
s a=20
JTAG superset. (used by Infineon/Motorola/Atmel and others) .
The protocol of some of the uC is not good for fullspeed USB becouse a re=
ad=20
address is only a 3 byte sequence with opcode, lowbyte, highbyte what is=20
followed by a single byte response from device. Such ping - pong transmis=
sion=20
in reading consecutive addresses would change the direction too offen and=
=20
not fill the 64 bytes of a full speed buffer. This slows down the availab=
le=20
bandwidth to less than 9,6kBaud even if host polls every msec. Thats why =
I=20
think about more abstract telegram sequences what can fit the 64 byte slo=
ts=20
and make a protocol translation inside the cable.
With other words: I like to use a report identifier in the first byte wha=
t=20
indicates the type of report. After that, 63 bytes of raw data follow. Th=
is=20
data is in the moment exactly what goes over the other interfaces of the=20
uC. The content can be considered as raw data, the instructions are=20
defined by semiconductor manufacturers and the order and content depends =
from=20
the file what user likes to download to uC chip. This moment int-in and=20
int-out endpoint are a exact copy of that what is going over the other=20
interface. For additional and rarely used commands (like setup of cable=20
baudrate or target voltage) I think its best to use a feature report with=
=20
control transfers. This avoids to pack and identify additional commands=20
inside the transparent stream of EP1/2. Tommorow I may have a better idea=
for=20
a more efficient protocol and set the report ID from 01 to 02 and then th=
e=20
cable is free to decode both contents.
To be more specific, the following is a report descriptor taken from the=20
Cypress Reference design #6401 for a RS232 converter cable what can possi=
bly=20
do most of the requirements of my device (except that there is no report =
ID).=20
I modified the maximum value to 255 to transmit 8 bit values what requier=
es a=20
16 bit argument for signed integer:=20
static DESCRIPTOR_MEMORY UCHAR ReportDescriptor[SIZE_ReportDescriptor] =3D
{
0x06, 0x0A0, 0xFF,=09 // Usage Page (FFA0H =3D vendor defined)
0x09, 0x01, // USAGE (Vendor Usage 1)
0xa1, 0x01, // COLLECTION (Application)
0x09, 0x01, // USAGE (Vendor Usage 1)input r=
eport
0x15, 0x00, // LOGICAL_MINIMUM (0)
0x26, 0xff, 0x00, // LOGICAL_MAXIMUM (255) was a bu=
g
0x75, 0x08, // REPORT_SIZE (8)
0x95, 0x40, // REPORT_COUNT (64)
0x81, 0x02, // INPUT (Data,Var,Abs)
0x09, 0x02, // USAGE (Vendor Usage 2) out re=
port
0x75, 0x08, // REPORT_SIZE (8)
0x95, 0x40, // REPORT_COUNT (64)
0x91, 0x02, // OUTPUT (Data,Var,Abs)
0x09, 0x03, // USAGE (Vendor Usage 3) featur=
e rep
0x75, 0x08, // REPORT_SIZE (8)
0x95, 0x05, // REPORT_COUNT (5)
0xb1, 0x02, // FEATURE (Data,Var,Abs)
0xc0 // END_COLLECTION
};
Linux seems to read the report descriptor but what instance is doing anyt=
hing=20
with this descriptor? Therefore the application is responsible? This only=
used=20
for mice and keyboards?=20
With the USB Firmware I first=20
tried to start with the full speed library from STM what can be downloade=
d=20
from www.stmcu.com but I give that up soon becouse the thing contains too=
=20
much inline assembly and too many people were involved in writing this co=
de=20
and each one seems not to understand what the previous did. Thats why I=20
started writing a own one using computed jumps to decode the device reque=
sts.=20
Its completely C and occupies currently about 600 bytes plus descriptor d=
ata=20
what are that moment in experimantal version:
;************************************************************************=
**************************
; public symbols
=09xref _cnfdsc,_str0,_str1,_str2,_devdsc,_repdsc,_hiddsc
_devdsc:=09dc.b 0x12=09=09;0 bLength, the Standard Device Descriptor leng=
th is 0x12=20
=09dc.b 0x01=09=09;1 bDescriptorType is Device, USB spec 2.0, page 251, t=
able 9-5
=09dc.b 0x10,0x01=09; Complies with USB Spec. Release (0110h =3D release =
1.10)
=09dc.b 0x00=09=09;4 bDeviceClass, each interface comes with individual c=
lass
=09dc.b 0x00=09=09;5 bDeviceSubClass, must be zero if bDeviceClass is als=
o zero
=09dc.b 0x00=09=09;6 bDeviceProtocol, no class specific protocol on inter=
face basis
=09dc.b 0x08=09=09;7 maximum packet size for endpoint0, the ST7 would als=
o allow 16
=09dc.b 0x70,0x0c=09;8,9 idVendor for www.elektronikladen.de 0x0c70
=09dc.b 0x3f,0x07=09;a,b idProduct ID for the Cable 0x073f
=09dc.b 0x01,0x00=09;c,d bcdDevice indicates product version 00.01
=09dc.b 0x00=09=09;e (01) iManufacturer, Index of String=20
=09dc.b 0x02=09=09;f iProduct, Index of String what describes the product
=09dc.b 0x00=09=09;10 iSerialNumber,=20
=09dc.b 0x01=09=09;11 bNumConfigurations, there is only one configuration=
possible
_cnfdsc:=09dc.b 0x09=09=09;0 bLength, the Standard Configuration Descript=
or=20
=09dc.b 0x02=09=09;1 bDesciptorType is Config, see USB spec 2.0, page 251=
, table 9-5
=09dc.b 0x22,0x00=09;2,3 wTotalLength, of following descriptors of this c=
onfig
=09dc.b 0x01=09=09;4 bNumInterfaces, this configuration has one interface
=09dc.b 0x01=09=09;5 bConfigurationValue, is selected by this value
=09dc.b 0x00=09=09;6 iConfiguration, Index of String describing this conf=
iguration
=09dc.b 0x80=09=09;7 bmAttributes, bus powered
=09dc.b 0x32=09=09;8 bMaxPower in 2 mA steps, this are 100 mA
_ifdsc:=09dc.b 0x09=09;0 bLength, Descriptor length is 9 from 0 to 08
=09dc.b 0x04=09;1 bDescriptorType is Interface Descriptor
=09dc.b 0x00=09;2 bInterfaceNumber, identifies this Interface
=09dc.b 0x00=09;3 bAlternateSettung, value used to select alternate setti=
ng
=09dc.b 0x01=09;4 bNumEndpoints, number of endpoints used additional to E=
P0
=09dc.b 0x03=09;5 bInterfaceClass, is a Human Interface Device
=09dc.b 0x00=09;6 bInterfaceSubClass, no subclass not bootable
=09dc.b 0x00=09;7 bInterfaceProtocol, this device uses no protocol
=09dc.b 0x00=09;8 iInterface, Index to String describing the interface
_hiddsc:=09dc.b 0x09=09=09;0 bLength, Descriptor length is 9 from 0 to 08
=09dc.b 0x21=09=09;1 bDescriptorType is HID
=09dc.b 0x00,0x01=09;2,3 bcdHID complies with HID version 1.0
=09dc.b 0x00=09=09;4 bCountryCode, 0=3Dnot supported
=09dc.b 0x01=09=09;5 bNumDescriptors, one class specific descriptor will =
follow
=09dc.b 0x22=09=09;6 bDescriptorType what followes is a report descriptor
=09dc.b repend-_repdsc
=09dc.b 0x00=09=09;7,8 wDescriptorLength, total size of report descriptor
_epdsc:=09dc.b 0x07=09=09;0 bLength, Descriptor length is 7 from 0 to 6
=09dc.b 0x05=09=09;1 bDescriptorType is endpoint descriptor
=09dc.b 0x81=09=09;2 bEndpointAddress, bit 0=3D1 is IN Endpoint, bit 1,2,=
3 is address
=09dc.b 0x03=09=09;3 bmAttributes, bit1,0=3DInt transfer, other bits=3D0 =
non isochron
=09dc.b 0x06,0x00=09;4,5 wMaxPacketSize is 6 bytes
=09dc.b 0x0a=09=09;6 bInterval for polling endpoint in number of frames, =
10 msec
_repdsc:=09dc.b 0x06,0xa0,0xff=09;USAGE_PAGE (Vendor Defined FFA0)
=09dc.b 0x09,0x01=09;USAGE (Vendor Usage 1)
=09dc.b 0xa1,0x01=09;Collection (Application)
=09dc.b 0x09,0x02=09;Usage (Vendor Usage 2)
=09dc.b 0xa1,0x00=09;Collection Physical
=09dc.b 0x06,0xA1,0xFF=09;Usage Page (vendor defined)=20
=09dc.b 0x09,0x03=09;usage - vendor defined
=09dc.b 0x09,0x04=09;usage - vendor defined
=09dc.b 0x15,0x80=09;Logical Minimum (-128)
=09dc.b 0x25,0x7F=09;Logical Maximum (127)
=09dc.b 0x35,0x00=09;Physical Minimum (0)
=09dc.b 0x45,0xFF=09;Physical Maximum (255)
=09dc.b 0x75,0x08=09;Report Size (8) (bits)
=09dc.b 0x95,0x02=09;Report Count (2) (fields)
=09dc.b 0x81,0x02=09;Input (Data, Variable, Absolute), that was the input=
report
=09dc.b 0x09,0x05=09;usage - vendor defined
=09dc.b 0x09,0x06 =09;usage - vendor defined
=09dc.b 0x15,0x80 =09;Logical Minimum (-128)
=09dc.b 0x25,0x7F =09;Logical Maximum (127)
=09dc.b 0x35,0x00 =09;Physical Minimum (0)
=09dc.b 0x45,0xFF =09;Physical Maximum (255)
=09dc.b 0x75,0x08 =09;Report Size (8) (bits)
=09dc.b 0x95,0x02 =09;Report Count (2) (fields)
=09dc.b 0x91,0x02 =09;Output (Data, Variable, Absolute) =20
=09dc.b 0xC0=09=09;End Collection
=09dc.b 0xC0=09=09;End Collection
repend:=09dc.b 0
;************************************************************************=
**************************
; string descriptors, read USB Spec 2.0 page 273 chapter 9.6.7, String 0=20
announces the languages
; supported by the device but language identifier codes are not found in =
the=20
USB specification
; For Language ID read seperate document "langids" version 1.0 issued 3/2=
9/00
=20
_str0:=09dc.b 0x04,0x03,0x09,0x04=09;language ID Englisch (US)
_str1:
_str2:=09dc.b _str3-_str2=09=09;lenght of string in bytes
=09dc.b 0x03=09=09=09;constant for string descriptors
=09dc.b "C",0x00,"a",0x00,"b",0x00,"l",0x00
=09dc.b "e",0x00
_str3:=09=09
=09end
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