Re: Wich 16-bit MCU?

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.

You don't say how much RAM, but a good starting system, could be the
C8051F064EK from Silabs. Just ~$25, and you get Debug, 16 bit 1 MSPS ADC, 12 bit DAC, 128K RAM, and USB.
The PC link sounds close to a USB, which is much smaller/cheaper than
SCSI.

Or use 10/100 Ethernet, and choose the AX11015, with external ADC/DAC.

Since uC+ADC are about the same price as ADC alone these days, you
could also consider a 2 chip solution : one to handle the PC link, and
one to handle 'smart' ADC/DAC ?


.

Relevant Pages

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  • Re: Wich 16-bit MCU?
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  • Wich 16-bit MCU?
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