Re: [Discuss-gnuradio] Reading registers on the USRP

[kevinmbo]

I've read that post before.  It more or less gave me reassurances on what
I had gathered that had to be done to implement a simple in-line
multiplier in the TX chain.  The post tells me what registers are
readback, but not how to read them back.  When I came across the post
originally, it pointed me in the right direction to where I should connect
the output of my new module.

-Kevin


> address@hidden wrote:
>> Hi,
>>
>> I'm having a little trouble reading the readback registers that are on
>> the
>> USRP.  I know that most registers are write only with their contents
>> mirrored on the computer.  The reason I want read those registers back
>> is
>> because of a custom unit I am testing.  I currently load a custom
>> implementation on the USRP that consists of 1 TX chain and 2 custom
>> units,
>> one of which feeds back information into the unused readback ports
>> (rssi0
>> to rssi3). I'm able to read from the capabilities register using
>> '_read_fpga_register(FR_RB_CAPS)' and it returns a value that makes
>> sense.
>>  When I try reading from any other register, the value returned is
>> consistently '0'.  I'm reading the registers in a loop in case the value
>> changes after a given amount of time.  I'm not sure what to try next,
>> can
>> someone give me a new direction?
>>
>> -Kevin
>
> This post might help:
>
> http://lists.gnu.org/archive/html/discuss-gnuradio/2007-05/msg00356.html
>
> -Roshan
>