[time-nuts] Small CPLD/FPGA for microcontroller replacement

Didier Juges didier at cox.net
Fri Feb 5 14:04:16 UTC 2010

It looks like I will have to get educated on CPLD/FPGAs on short notice.

My application at the moment will be the replacement of small
microcontrollers for military and commercial aviation projects that do not
want/tolerate software/firmware (some customers and government regulations
do not consider CPLD/FPGA to be containing software, which to a large extent
is a matter of opinion, but this is not a thread I wish to start at this
time). The FAA in particular puts a much greater burden on microcontrollers
than CPLD/FPGAs when it comes to demonstrating compliance to DO-254 in
safety critical applications like battery charging.

The microcontrollers I have been using are typically from 20 to 100 pins
(Silabs 8051 family) with a lot of integrated peripherals. I understand I
will have to use external peripherals like ADC, DAC, probably clock
oscillator and such with a CPLD/FPGA, where these functions are currently
integrated in my microcontrollers.

Part of the requirement is that the devices be immune (as much as practical)
from SEU malfunction. I was told Atmel (or Actel?) makes flash-based small
FPGAs that may fit the bill. Most SRAM devices are deemed to be excessively
sensitive to SEU, even though I cannot imagine how a CPLD/FPGA could be made
that does not use SRAM at all. Maybe it's a matter of quantity? A few
working registers may be an acceptable risk, but the entire device operating
from SRAM is not acceptable?

I am looking for any information/recommendation on which families to look

Thanks in advance,

Didier KO4BB 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of John Miles
Sent: Thursday, February 04, 2010 8:43 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] CPLDs for clock dividers

Yeah, Xilinx 11 is pretty nice.  I'm usually allergic to IDEs, especially
theirs, but I've been pretty happy with 11 so far.  I find myself using it
instead of my tried-and-true makefile for FPGA work, and that's saying

-- john, KE5FX

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