Re: Wich 16-bit MCU?

On Thu, 29 Jun 2006 10:09:02 +0000, Robert Latest wrote:

Hello,

I'm now at the point where I'll have to dive into building an embedded
data acquisition system. Last time I did that was about 15 years ago --
burn-and-crash with an 68008 and an EPROM, much along the lines of Chapter
11 in AoE (just to illustrate the point at which my uC knowledge froze
over).

What I need to do, in real-time, is this -- just to estimate the workload
the CPU has to cope with:

1. Read out one 16-bit ADC at 60 kHz rate, do a bit with the numbers and
write back out to an ADC at the same rate. This is a PI servo loop that
also could be done in analog hardware if the CPU isn't up to it.

2. Read out three 16-bit ADCs at 20kHz rate and store results in RAM 3.
Update two 16-bit DACs at 20kHz (numbers come from a couple of
Bresenham's algorithms).

4. simple link to host Computer, 800kB/sec (SCSI?)

Task 1. must run continuously. Tasks 2 and 3 run simultaneously but
alternatingly with 4.

Based on what I've done I'm partial towards the 68k assembler, so I looked
at Freescale's website and found the aged, but pretty attractive MC68332
MCU. Then there's their Coldfire product line which seems to be a bunch of
faster/cheaper variants of the same theme.

My problem is getting started with all this. I don't want to drag the old
EPROM burner out of the basement; I think the latest fad (late as of
probably 15 years ago) is in-circuit programmability and -debugging.

I'm just wondering into which architecture should I invest time and money
in terms of a development system, and how much. Unfortunately the app
notes I found on many MCU vendors mainly cover embedded networking
applications and not the more down-to-earth stuff I'm interested in. Like
I said, I like m68k assembler but I've heard good things about ARM, too.

Thanks,
robert

Considered a Freescale S12X ?

16-bit mcu with additional 16-bit RISC co-processor designed for I/O
intensive tasks. Allows interrupts to be shared between cores.

Take a look at:

http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MC9S12XA256&nodeId=0162468636K1003631

There's an open source 1-wire debug interface available, costs < $10 to
build, or can buy I think.

--
Steve


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