Re: Faster than TI C2000?


"CC" <crobc@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:N4Wak.10936$cW3.9354@xxxxxxxxxxxxxxxxxxxxxxx
Vladimir Vassilevsky wrote:

Chris Carlen wrote:

Even though I am able to do what I want with the existing 150MHz
TMS320F2812 digital signal controller (DSC), I am always eager to have
more speed, since applications that were otherwise inconceivable may
become possible if more speed becomes available.

What kind of application do you need the high speed for?

At present I am generating 1us resolution arbitrary pulse sequences
using compare matches. There must be no jitter so HW compare match to
generate the edges is essential. I might need to make a waveform like:

START
delay 4us
high 15us
low 12us
high 30us
low 60us
high 10us
low 14us
...
STOP

This is the traditional application for the state machines implemented in
the hardware, such as PLD or FPGA. Some MCUs provide the programmable
sequencers for that (68HC16, for example). It can be also done with the use
of the DMA channels.


For instance, would folks be interested in a 300MHz device with 16-32k
of data+code space capable of running no wait states at a full 300MHz,
where the larger 256-512k flash requires wait states making it only
effectively 75-90MHz?

This is BlackFin.

I am aware of much faster devices.

With BlackFin, you can have a pure software solution with the interrupt
driven bit banging. The timing jutter could be less then 100ns, and the
generation of the pulses of the minimum length of 1us with the resolution of
~10ns is no problem. The other option is DMAing directly to the port, with
no jitter at all.

What C2000 has is *peripherals*.

Yes, the timer event manager subsystem of TMS 28xx is impressive.

TMS 28xx is not very fast, if compared to D*** or FreeScale 56xxx, or
especially to BlackFin.

I don't see how you can consider it slow compared to 40MHz 16 bit. It
is way faster.

Not quite so. TMS 28xx is not a DSP, it is MCU. It is quite inefficient on
the DSP operations like FIRs or IIRs.

Blackfin is a totally different animal. It's not a DSC. It doesn't
have 4 waveform generation timers, QEP inputs, etc. It has lots of nice
ways to get data in and out of the chip, but it is essentially a
microprocessor.

BlackFin is fast MCU with good DSP capabilities.

It has less GPIO than F2812 without going to a 400ball
BGA. There are only 2 devices with LQFPs.

The 12mm BGA is nice small package. The only problem is the need for 4+
layer board. BlackFin in LQFP can be put on the two layer board.

I work in a lab. I chose the F2812 because the power/complexity ratio
seemed better than anything else when it came out.

Good point about power/complexity ratio. I agree, F28xx is good by this
parameter.

Yes, that is true. I chose to experiment with the F2812 with no
application, but simply had read about it in comparison to DSPics, ARMs,
SHARCs, and the new Blackfin, and it seemed like a good step up from the
AVRs that I was using for little things, yet easy enough to understand
and get to do some intersting things without having to first understand
a great deal of supporting infrastructure of setting up MMUs, OSes,
etc., or having to build PWM generators and QEP decoders in an FPGA.

Why didn't you buy an arb generator or timer board from NI then? It could
save you a lot of effort.

VLV


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