Looking for very fast MCU, any advice?

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teuniz Contact options for registered users 's Avatar (by Gravatar) posted on
February 21, 2007, 10:12 am
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Hello,

I am using a PIC18F4620 as an universal "workhorse" in many
applications
and I like this MCU because of its versatility and it's easy to use.

Recently I am experimenting with an USB-interface chip from FTDI. This
works nice
but now I am designing a multichannel ADC at high speed. The problem
now is that
the MCU is not fast enough to control the ADC-chip, buffer the data
and control the
USB-chip when working at a high througput.

Does anybody know about a faster replacement for the the PIC18F4620?
Requirements:

- about 100 MIPS
- easy housing, preferable DIP
- built in RAM and ROM
- easy (re)flashable

Any recommandations?

Regards, Teuniz


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TT_Man Contact options for registered users 's Avatar (by Gravatar) posted on
February 21, 2007, 10:51 am
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Re: Looking for very fast MCU, any advice?



<>
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1 processor per channel? 8 pin pic?



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teuniz Contact options for registered users 's Avatar (by Gravatar) posted on
February 21, 2007, 12:06 pm
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Re: Looking for very fast MCU, any advice?


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How do I interface multiple MCU's to one USB-interface chip(FT245R)??

Because the FTDI-chip has only a 64-byte FIFO and USB can be busy
sometimes, I need to buffer the data from the ADC-chip as well.
The small PIC's don't have enough RAM.


Scott Seidman Contact options for registered users 's Avatar (by Gravatar) posted on
February 21, 2007, 1:17 pm
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Re: Looking for very fast MCU, any advice?


snipped-for-privacy@gmail.com wrote in news:1172059609.187817.226620
@h3g2000cwc.googlegroups.com:

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An additional PIC to handle USB?
--
Scott
Reverse name to reply

teuniz Contact options for registered users 's Avatar (by Gravatar) posted on
February 21, 2007, 2:12 pm
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Re: Looking for very fast MCU, any advice?


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A 4-channel 16-bit ADC,  AD974 from Analog Devices connected via SPI.

For the moment, I want to let it run at 10K smp/sec. per channel.
So I have to buffer and transfer 80KB/sec. to the FT245R which has an
8-bit wide parallel interface.

I put optocouplers in the SPI-bus because isolation is needed. Because
of these opto's the max clockspeed on the SPI-bus is 2.5MHz.




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James Beck Contact options for registered users 's Avatar (by Gravatar) posted on
February 21, 2007, 3:17 pm
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Re: Looking for very fast MCU, any advice?


snipped-for-privacy@gmail.com says...
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OK, you can get that kind of throughput with SPI.  I was just curious.
Can you get that kind of continuous throughput over a FT245R?  I haven't
played with any of those USB bridge parts yet, BUT I am looking at doing
a USB project soon and I think one of the off the shelf USB to
serial/parallel IC's might just be the ticket.

                         Jim



James Beck Contact options for registered users 's Avatar (by Gravatar) posted on
February 21, 2007, 12:52 pm
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Re: Looking for very fast MCU, any advice?


snipped-for-privacy@gmail.com says...
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What amounts of RAM and ROM?
100 MIPS is getting near the upper end for an internal memory MCU.
Have your looked at the ARMX stuff?
How about that Parallax Propellor IC?  8 32 bit MCU's with a built in
round robin scheduler.
Maybe some of the PIC24 series, may not hit 100 MIPS, but the 16 bitness
might make up for that.  
Lots of possibilities.  
What kind of DAC are you using, interface wise?

                    Jim

Jens Gydesen Contact options for registered users 's Avatar (by Gravatar) posted on
February 23, 2007, 5:01 pm
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Re: Looking for very fast MCU, any advice?


Sounds like a DSP and a USB CPU


/JG

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