Re: [Discuss-gnuradio] USRP2 firmware build

[Eric Blossom]

On Fri, Oct 03, 2008 at 11:10:36PM -0700, Matt Ettus wrote:
> Jeff Long wrote:
>> Generated a new txrx.bin using EDK101 and put it on the SD
>> card.  Works!  I'm assuming that's the correct app, based on
>> strings on the provided SD.  BTW, is any of this documented
>> yet?
>
> Yes, txrx is the correct app to use, and is the one which is on the SD  
> card which I ship out.  No, we don't really have this written anywhere.   
> I've been putting stuff on the USRP2 FAQ page on the wiki, but clearly  
> this is a lot which still needs to be documented.

txrx is the standard firmware at this point.

>> Where do printf's go to?
>
> They go to the serial port on the right side of the USRP2, between the  
> two daughterboards.  You would have to connect a TTL-level serial port  
> to it, at 230,400 baud.
>
>>
>> Using -Os vs. -O2 shaves off another 500 bytes if you ever
>> need the space.  Takes txrx.bin from 26028 to 25484 bytes.

Good to know.  We'll need to see how the inner loop holds up.
At decim = 4 and/or interp = 4, it's close to being the bottleneck.


> I was thinking that -Os would probably be a good thing to try.  Having  
> only 32K of RAM can be a bit constraining.
>
>> The function __udivdi3 is 1836 bytes long, and is only used
>> in print_uint64, which is used only in printf_fxpt_freq.
>> That might be something to get rid of.

> Wow, 1836 bytes is a lot.

Right now __moddi3, __umoddi3, __divdi3 and __udivdi3 contain inlined
versions of __udivmoddi4.   Un-inlining them should save about 5KB in
the worst case, 4KB typical.  I'm working on it.  (These routines
implement signed and unsigned 64-bit divides and mods.  We use these
in dealing with our 64-fixed point frequency representation.)


Jeff, which RFX board are you using?


Eric