[FOSS-GPS] RTKLib MIPS requirements?

Wed May 2 17:08:11 EDT 2012

Well correct me if I'm wrong but this seems to come down to how many 
flops it can do, the moving of variables and such is probably a minority 
of the processing.  That's why I wanna focus on the flops requirement.

How much resources does RTKLib consume on Beaglebone?  Because BB being 
faster and capable of RTKLib still doesn't establish the processing 
requirements.  Is it running at 60% core utilization or 5%?

I did run RTKLib on my i7 Q 740 1.73GHz laptop and the utilization was 
basically nil.  I really couldn't determine anything from that, the 
usage figure was too low to give a meaningful number, not when the 
capabilities are at least 100x greater.  I mean if the usage was 10% on 
that i7 I could pretty well dismiss it working on a Cortex M4.  IIRC it 
was like a single-digit or fractional % though and the OS can consume 
considerable resources managing the busses and displaying the maps and 
interfaces so that doesn't mean much.

Raspberry PI would be nice, but I can't get ahold of one, much less will 
it be readily available at this time for widespread consumption if the 
application worked.  I'm still uncertain if widespread, long-term, 
low-price distribution is gonna happen or just turn out to be 
vaporware.  STM32F4, anybody CAN order one or a thousand and get them 
for $15 or better right now.  Still got high hopes of course.  Raspberry 
PI also wasn't designed with a lot of low-level hardware interfacing so 
it'd still require a daughterboard like the STM32F4 to interface with a 
rover's motors and sensors and all.

Danny

On 5/2/2012 3:40 PM, Michele Bavaro wrote:
> Hi Danny,
>
> I strongly doubt that a STM32F4 will be able to run RTKLIB.
> It's true that it runs on a beaglebone, but Cortex-A8 has around 
> 2MIPS/MHz and runs at frequencies close to 1GHz,
> whereas a Cortex-M4 has 1.25MIPS/MHz and runs at frequencies up to 
> 150MHz: there is almost one order of magnitude.
> In addition since the structure of rtkrcv is quite strongly coupled 
> with a Linux OS,
> there will be a lot of effort required to port it to a lighter RTOS, 
> let go to bare metal code.
>
> But I don't want to discourage you.. if you think it's doable go for 
> it :)
>
> Best regards,
> Michele
>
> On 02/05/2012 00:15, Danny Miller wrote:
>> STM32F4 "demo board" uses an Arm Cortex m4.  32 bit, 210 DMIPs and a 
>> single-precision hardware FPU.  I'm slightly unclear on the memory 
>> space it has on this specific board but it should be 192KB SRAM and 
>> 1MB flash.  That's my porting plan.
>>
>> If it WORKS, it'll be a great system, these boards are absurdly 
>> cheap.  It is several more orders of magnitude of capability than 
>> these 8bit PICs and such, but I don't understand the scale of the 
>> flops requirement of RTKLib.  I know it's somewhere between "much 
>> more than any 8-bit controller could ever do" and "won't even make 
>> Intel i7 break into a sweat".   And those are wildly different 
>> magnitudes.  I don't know exactly where RTKLib 10Hz would be between 
>> those.
>>
>> And it's be running RTKLib and just some minor application 
>> (navigation and monitoring) code which will not be 
>> processor-intensive, and it's not using Linux or an RTOS.  So there's 
>> not a significant overheat for other tasks and the overhead's timing 
>> can be managed predictably and accurately.  Pretty much the core can 
>> either do it or it can't.
>>
>> Danny
>>
>> On 5/1/2012 4:43 PM, julio menezes wrote:
>>> Hi Danny,
>>>
>>>
>>>> I have a core with a hardware FPU, but it's only capable of
>>>> doing Single floats, not Double.  It is going to break
>>>> things to implement the specified Double calcs with Single
>>>> precision?  I would assume so, but it's worth asking.
>>>>
>>> The RTKLIB author T.Takasu and A.Yasuda have  ported RTKLIB to a 
>>> BeagleBoard which has an ARM Cortex-A8- with 1 GHz and floating 
>>> point, I do not know if double or single precision.
>>>
>>> I plan to move in this direction also, may be using a hardware less 
>>> powerful but cheaper.
>>> Raspberry Pi
>>> http://www.raspberrypi.org/faqs
>>> The SoC is a Broadcom BCM2835.
>>> This contains an ARM1176JZFS, with floating point, running at 
>>> 700Mhz, and a Videocore 4 GPU.
>>>
>>> I am waiting, anxiously,  the RTKLIB 2.4.2 version with RTCM-104 
>>> phase messages encoder to built a local base station as where I live 
>>> there are no near NTRIP network ( less than 10km ).
>>>
>>> good luck,
>>>
>>> julio menezes
>>>
>>>
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