Reading and writing registers

GNU Radio
1

Hi

I am having some trouble trying to get register writing and reading from
the C++ level to work. I’ve created two methods:

for writing

static bool
write_a_reg (usrp_basic *u, int address, int amount)
{
bool isit = u->_write_fpga_reg (address, amount);

return isit;
}

for reading

int
read_a_reg (usrp_basic *u, int address)
{
int val = u->_read_fpga_reg (address);

return val;
}

When I use the write method:

bool fine2 = write_a_reg (urx, 78, 60);

The returned boolean indicates that the write was successful. If I try
to read the same register though:

int value = read_a_reg (urx, 78);

it always returns zero no matter what I put in. The urx is the handle of
a usrp_standard_rx object, and if I’m not mistaken, register number 78
(`FR_USER_14) shoul be free to use. What am I doing wrong?

Regards

Lance

2

On Fri, Nov 03, 2006 at 02:43:46AM -0800, seph 004 wrote:

Hi

return isit;
}
register number 78 (`FR_USER_14) shoul be free to use. What am I
doing wrong?

Regards
Lance

Assuming that all registers are readable, or that they
are in the same address space as the writable registers would be a
mistake.

Try reading from registers 1, 2 or 3. See
usrp/firmware/include/fpga_regs_standard.h, down toward the bottom.

Please also note that writing random values into random registers can
lead to permanent damage. FR_USER_0 through FR_USER_15 are safe to
write with the .rbf’s that we distribute. We don’t pay any attention
to them.

Eric