[FOSS-GPS] RTKLib MIPS requirements?

Tue Aug 14 02:06:37 PDT 2012

Since Raspberry Pi finally became available, I've moved away from an 
STM32F4 attempt.  There's not much purpose to it.

Raspberry takes some getting used to, I'm not very familiar with 
Linux.   The Debian Squeeze release that was out when Pi was released 
became obsolete in mid-July with the much faster, friendlier Debian 
Wheezy release.  This is important because Wheezy uses the Pi's hardware 
FPU, Squeeze did not, which is why it was so slow.  RTKLIB needs that FPU.

I was delighted to find that Debian readily recognized the Silabs CP2102 
USB-to-serial bridge and even the uBlox GPS's USB port. And on the GPIO 
pins, it also has a serial port there which is supported by the OS.

RTKRCV does compile with the GCC included in the Debian release. 
However, I'm a bit unclear on how to configure the setup (calling one 
GPS a static base station, for example), pass it the ports and what sort 
of messages I can expect out of it.  There's not going to be any way to 
run the GUI version, I assume?  Windows emulators like Wine will never 
run on the Pi.

Danny

On 8/14/2012 2:35 AM, Michele Bavaro wrote:
> Hello Danny,
>
> Have you done any real progress with STM32F4 then?
>
> Best regards,
> Michele
>
>
>
> On 03/05/2012 14:45, Danny Miller wrote:
>> I remember seeing that a long time ago, but forgot about it. Hmm, it 
>> does have useful figures.
>>
>> The A8 at 600MHz would be capable of 1200 DMIPS.  At 20% utilization 
>> for 10Hz GPS operation that would indicate 240 DMIPS used, and that's 
>> with the TMS320C64x DSP.  However, AFAIK that's not a floating-point 
>> DSP core and I expect you'd have to do a lot of tinkering with the 
>> compiler to get it to send any math to the DSP core.  I suspect it 
>> wasn't used.  The article doesn't mention the TMS320C64x DSP except 
>> in the Beagle specs.
>>
>> The STM32F4 is capable of 210 DMIPs.  Hmm, that's troubling. There's 
>> still overhead which hasn't even come into play yet.  I would expect 
>> compiling to metal would be substantially more efficient but I don't 
>> KNOW that.  Then again, it doesn't HAVE to be 10Hz, we could go with 
>> 5Hz operation, there's no law saying it has to be 10Hz.  Plenty of 
>> overhead at that speed.
>>
>> Danny
>>
>> On 5/3/2012 1:04 AM, Michele Bavaro wrote:
>>> Dear Danny,
>>>
>>> Sorry, I assumed that you read this paper
>>> http://gpspp.sakura.ne.jp/paper2005/isgps_2009_rtklib_revA.pdf
>>> before posting.
>>> There you may find more details about RTKLIB computational load at 
>>> 10Hz.
>>>
>>> Best regards,
>>> Michele
>>>
>>>
>>> On 02/05/2012 23:08, Danny Miller wrote:
>>>> 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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