How do I read a USB joystick? - SUN
This is a discussion on How do I read a USB joystick? - SUN ; I need to read a USB joystick on a Solaris system from an application
program. The vendor has given me a copy of the 7-byte report package
format, but my test program is not giving me correct values. Can
someone ...
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How do I read a USB joystick?
I need to read a USB joystick on a Solaris system from an application
program. The vendor has given me a copy of the 7-byte report package
format, but my test program is not giving me correct values. Can
someone either tell me what I'm doing wrong or just tell me the correct
method? Thanks.
My test program is:
#include
#include
#include
#include
void main()
{
signed char data[8];
int moreFlag;
int fd;
fd = open("/dev/usb/hid6",O_RDONLY);
if (fd == -1)
{
printf("\n OPEN FAILED\n");
exit(0);
}
printf("\n OPEN PASSED\n");
moreFlag = 1;
while (moreFlag == 1)
{
moreFlag = read(fd, &data[0], 7);
if (moreFlag < 1)
printf("\n read returned %d\n", moreFlag);
else
{
printf("read %d bytes (in reverse): ", moreFlag);
while (moreFlag > 1)
{
moreFlag--;
printf("%d, ", (int)data[moreFlag]);
}
printf("%d\n enter 1 to repeat, anything else to stop: ",
(int)data[0]);
scanf("%d", &moreFlag);
}
}
printf("\n\ngood-bye\n");
close(fd);
}
Thanks.
Scott B. Klein
Senior Engineer
Northrop Grumman Electronic Sensors
Baltimore, Maryland 21203-0746
Telephone (410) 765-0910
s.klein@ngc.com
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Re: How do I read a USB joystick?
s.klein@ngc.com writes:
>I need to read a USB joystick on a Solaris system from an application
>program. The vendor has given me a copy of the 7-byte report package
>format, but my test program is not giving me correct values. Can
>someone either tell me what I'm doing wrong or just tell me the correct
>method? Thanks.
>My test program is:
>#include
>#include
>#include
>#include
>void main()
>{
> signed char data[8];
> int moreFlag;
> int fd;
> fd = open("/dev/usb/hid6",O_RDONLY);
> if (fd == -1)
> {
> printf("\n OPEN FAILED\n");
> exit(0);
> }
> printf("\n OPEN PASSED\n");
> moreFlag = 1;
> while (moreFlag == 1)
> {
> moreFlag = read(fd, &data[0], 7);
If you want to read 7 bytes, you may need to do things like:
toread = 7;
while (toread > 0) {
nread = read(fd, &data[7-toread], toread);
if (nread <= 0) {
/* Exceptional circumstances? */
break;
}
toread -= nread;
}
/* Done reading packet */
if (toread == 0) {
/* Read all 7 bytes */
}
You may also want to read unsigned bytes and you may want to
look at possible ways to synchronize unsynchronized data
streams.
Casper
--
Expressed in this posting are my opinions. They are in no way related
to opinions held by my employer, Sun Microsystems.
Statements on Sun products included here are not gospel and may
be fiction rather than truth.
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Re: How do I read a USB joystick?
Thanks for your reply, but I guess that I wasn't clear. The read
successfully read the correct 7 bytes, but the values were not correct.
Not matter how I moved the joystick or pressed the buttions, the values
were either 0, 127, or -128. Even without touching the joystick, values
whould change.
An additional note is that I connected the joystick to my PC, the
Windows Joystick Properties Test tool graphically displays the correct
values for the joystick functions, so I know that it is not a hardware
problem. Thanks.
Scott
