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I remember seeing that a long time ago, but forgot about it. Hmm,
it does have useful figures.<br>
<br>
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.<br>
<br>
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.<span style="color: rgb(34, 34, 34);
font-family: arial, sans-serif; font-style: normal; font-variant:
normal; font-weight: normal; letter-spacing: normal; line-height:
16px; orphans: 2; text-align: -webkit-auto; text-indent: 0px;
text-transform: none; white-space: normal; widows: 2;
word-spacing: 0px; -webkit-text-size-adjust: auto;
-webkit-text-stroke-width: 0px; background-color: rgb(255, 255,
255); font-size: small; display: inline !important; float: none; "><span
class="Apple-converted-space"></span></span> 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.<br>
<br>
Danny<br>
<br>
On 5/3/2012 1:04 AM, Michele Bavaro wrote:
<blockquote cite="mid:4FA21FE6.1020804@yahoo.co.uk" type="cite">Dear
Danny,
<br>
<br>
Sorry, I assumed that you read this paper
<br>
<a class="moz-txt-link-freetext" href="http://gpspp.sakura.ne.jp/paper2005/isgps_2009_rtklib_revA.pdf">http://gpspp.sakura.ne.jp/paper2005/isgps_2009_rtklib_revA.pdf</a>
<br>
before posting.
<br>
There you may find more details about RTKLIB computational load at
10Hz.
<br>
<br>
Best regards,
<br>
Michele
<br>
<br>
<br>
On 02/05/2012 23:08, Danny Miller wrote:
<br>
<blockquote type="cite">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.
<br>
<br>
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%?
<br>
<br>
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.
<br>
<br>
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.
<br>
<br>
Danny
<br>
<br>
On 5/2/2012 3:40 PM, Michele Bavaro wrote:
<br>
<blockquote type="cite">Hi Danny,
<br>
<br>
I strongly doubt that a STM32F4 will be able to run RTKLIB.
<br>
It's true that it runs on a beaglebone, but Cortex-A8 has
around 2MIPS/MHz and runs at frequencies close to 1GHz,
<br>
whereas a Cortex-M4 has 1.25MIPS/MHz and runs at frequencies
up to 150MHz: there is almost one order of magnitude.
<br>
In addition since the structure of rtkrcv is quite strongly
coupled with a Linux OS,
<br>
there will be a lot of effort required to port it to a lighter
RTOS, let go to bare metal code.
<br>
<br>
But I don't want to discourage you.. if you think it's doable
go for it :)
<br>
<br>
Best regards,
<br>
Michele
<br>
<br>
On 02/05/2012 00:15, Danny Miller wrote:
<br>
<blockquote type="cite">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.
<br>
<br>
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.
<br>
<br>
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.
<br>
<br>
Danny
<br>
<br>
On 5/1/2012 4:43 PM, julio menezes wrote:
<br>
<blockquote type="cite">Hi Danny,
<br>
<br>
<br>
<blockquote type="cite">I have a core with a hardware FPU,
but it's only capable of
<br>
doing Single floats, not Double. It is going to break
<br>
things to implement the specified Double calcs with
Single
<br>
precision? I would assume so, but it's worth asking.
<br>
<br>
</blockquote>
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.
<br>
<br>
I plan to move in this direction also, may be using a
hardware less powerful but cheaper.
<br>
Raspberry Pi
<br>
<a class="moz-txt-link-freetext" href="http://www.raspberrypi.org/faqs">http://www.raspberrypi.org/faqs</a>
<br>
The SoC is a Broadcom BCM2835.
<br>
This contains an ARM1176JZFS, with floating point, running
at 700Mhz, and a Videocore 4 GPU.
<br>
<br>
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 ).
<br>
<br>
good luck,
<br>
<br>
julio menezes
<br>
<br>
<br>
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