[FOSS-GPS] RTKLib MIPS requirements?

[Michele Bavaro]

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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