Objective Development Forums

Re: usbFunctionSetup - 8 Bytes?

2010-10-04T20:31:23+02:00

omg it works!

i dont know anything about linux if it isn't that obvious. doing a make all "compiled?" a program for me which i was able to run from the terminal.

can anyone make a suggestion on what i should do next? my gut tells me to mess around with the functions.

Statistics: Posted by jay.elle — Mon Oct 04, 2010 8:31 pm

Re: usbFunctionSetup - 8 Bytes?

2010-10-04T15:19:47+02:00

_frank26080115 wrote:I have no idea what you don't understand, is it the typecasting?

I got way ahead of myself and tried to take in too much information. I didn't even build the project and mess with it at that point, which is what i'm doing right now.
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So far i flashed my metaboard with the custom class example that ships with the driver, but i can't build the host side application.

I started with libusb1.0 and realized i needed the legacy version so i backtracked all the way to libusb-0.1.10a. Everything seemed to install fine and my project can find usb.h, but now i've got different errors and i have no idea what they mean any ideas?

Code:

Samantha-Darkos-Mac-Pro:commandline SamanthaDarko$ gcc set-led.c
Undefined symbols:
  "_usb_close", referenced from:
      _main in ccdDCuMX.o
  "_usbOpenDevice", referenced from:
      _main in ccdDCuMX.o
  "_usb_init", referenced from:
      _main in ccdDCuMX.o
  "_usb_control_msg", referenced from:
      _main in ccdDCuMX.o
      _main in ccdDCuMX.o
  "_usb_strerror", referenced from:
      _main in ccdDCuMX.o
      _main in ccdDCuMX.o
ld: symbol(s) not found
collect2: ld returned 1 exit status
Samantha-Darkos-Mac-Pro:commandline SamanthaDarko$

Do i have to do something with the makefile?

Thanks,

Statistics: Posted by jay.elle — Mon Oct 04, 2010 3:19 pm

Re: usbFunctionSetup - 8 Bytes?

2010-09-26T05:12:43+02:00

I have no idea what you don't understand, is it the typecasting?

Statistics: Posted by Guest — Sun Sep 26, 2010 5:12 am

Re: usbFunctionSetup - 8 Bytes?

2010-09-25T04:43:04+02:00

_frank26080115 wrote:read http://www.beyondlogic.org/usbnutshell/ ... etupPacket

actually, read all the chapters

I did read all of the chapters. I think I need to study the code, just not too sure of how much because i'll start wondering how the asm code works.

Statistics: Posted by jay.elle — Sat Sep 25, 2010 4:43 am

Re: usbFunctionSetup - 8 Bytes?

2010-09-25T02:58:29+02:00

read http://www.beyondlogic.org/usbnutshell/ ... etupPacket

actually, read all the chapters

Statistics: Posted by Guest — Sat Sep 25, 2010 2:58 am

Re: usbFunctionSetup - 8 Bytes?

2010-09-24T00:09:22+02:00

This is wrong, the 8 bytes have already been received by the time that "usbFunctionSetup" is called.

Thanks Frank,

Could you please note some function that does this in the code and/or provide a simple explanation?
--
The wiki provides a very good explanation and shows great usage examples, but it's very high level and leaves me asking a lot of questions.

I'm unsure of how to understand and make use of this code, meaning do i use it as something high level / functions or would there be great benefit to understand all of the functions?

Statistics: Posted by jay.elle — Fri Sep 24, 2010 12:09 am

Re: usbFunctionSetup - 8 Bytes?

2010-09-23T17:55:04+02:00

The casting is done where it says "usbRequest_t *rq = (void *)setupData; // cast to structured data for parsing"

the structure of type "usbRequest_t" is 8 bytes long, thus you can easily obtain the request from this 8 bytes of data that is received by "usbFunctionSetup", that's what casting does, http://en.wikipedia.org/wiki/Type_conversion

My guess is that it takes 1 byte at a time until an ACK is received. Each time a byte is received how is the data parsed separately into its appropriate place?

This is wrong, the 8 bytes have already been received by the time that "usbFunctionSetup" is called.

Does this line point to the structure usbRequest and not usbRequest_t?

I don't understand this question because the word "usbRequest" does not appear anywhere. "usbRequest_t" is the name given to the structure type, while "rq" is the name given to a pointer that points to an instance of "usbRequest_t" converted from "setupData", and "bRequest" is a member of the "usbRequest_t" structure that "rq" is pointing at.

Statistics: Posted by Guest — Thu Sep 23, 2010 5:55 pm

usbFunctionSetup - 8 Bytes?

2010-09-23T10:27:03+02:00

Code:

 usbMsgLen_t usbFunctionSetup(uchar setupData[8])
{
    usbRequest_t *rq = (void *)setupData;   // cast to structured data for parsing
    switch(rq->bRequest){
    case 1:
        setLEDStatus(rq->wValue.bytes[0]);  // evaluate low byte only
        return 0;                           // no data block sent or received
    }
    return 0;                               // ignore all unknown requests
}

I know this is basic stuff,I'm trying to figure out how this function receives 8 separate bytes and stores it in to this structure:

Code:

 typedef struct usbRequest{
    uchar       bmRequestType;
    uchar       bRequest;
    usbWord_t   wValue;
    usbWord_t   wIndex;
    usbWord_t   wLength;
}usbRequest_t;

My guess is that it takes 1 byte at a time until an ACK is received. Each time a byte is received how is the data parsed separately into its appropriate place?

Code:

switch(rq->bRequest)

Does this line point to the structure usbRequest and not usbRequest_t?

Statistics: Posted by Guest — Thu Sep 23, 2010 10:27 am