Hysteresis on dsPIC ports?

industrial environment requires

It will.

This one just has to be small. I can make uC products work very reliably without fancy circuitry around them, have done it many times. _If_ the uC is properly characterized, which this one is not. I would not have picked it but was already in there.

What's the cost of fixing the many flaky internal power-on reset circuits that you've seen many of? :-)

In terms of components? Well under 50c, even in IC form. These little dudes are quite nice at around 15c a pop in qties:

The cost to the business before the fix? Huge. Because it often results in a service call, or a truck roll in utility speak.

They've probably never measured it, just inserted a library part ;-)

You _do_ know that you can safely put an R/C in front of a Schmitt input to get rid of large HF noise?

I came up with that VT/VBE from rail hysteresis gimmick (posted earlier today) during my ignition pick-up days... around 40 years ago... rejects even severe spark noise ;-) ...Jim Thompson

Done right, it's quite a bit of circuitry. One I did recently, that tested 3 supplies plus had a delay after voltages were AOK, was close to 15% of the active chip area :-( ...Jim Thompson

industrial environment requires

I'm not doubting your abilities, just we know what the constant is, the uC, and everything else goes from there.

We go through a truck load of DS1233s every year. Recently we had an assembler swap out the DS1233-15 for an MCP130-15 because their supplier told them it was a "drop in replacement", well, it isn't, and now we are dealing with a big retrofit of stocked units and some made it out into the field. Testing didn't stop to look at the part until a few units failed on the jig, and by then it was too late. Enough had passed to get out into the wild. Lesson learned, the hard way as usual. To top it off, he got his hands on some pulled/refurbished battery backed RAM that looks like Mr Haney from Green Aces worked it over for resale. All of that crap was immediately rejected.

On a sunny day (Wed, 27 Jan 2010 11:22:02 -0800) it happened Joerg wrote in :

PICs have that all build in :)

Yep, turn on the PUT, the WDT, the BOR, and you have a pretty damn good chance of powering up in a known state. Turn on the OSC fail interrupt and you are really cooking with gas.

Will PICs do "failover" to an internal RC clock if the xtal (or other external clock input) doesn't fire up? I used some MSP430s a large handful of years ago that did that, and thought it was pretty slick.

We use some Atmel AVRs at work that have this "tacked on" ability to use a

---Joel

Yes, but there comes a point where you introduce too much external latency when doing that.

My last ignition thingie was end of last year. But it's for a flying apparatus and not cars :-)

Get the library for the NCP30x from ON Semi? Don't you have good connections to them?

I wonder why they call the DS1233 "Econo Reset" when it it so much more expensive. But that mfg is on my no-traffic list anyhow.

Ouch. I bet someone was read the riot act later ;-)

Yes, finally. Here's hoping that it's good enough :-)

...Jim Thompson

Nope. That's proprietary to National. They'd never share their IP. ...Jim Thompson

On a sunny day (Wed, 27 Jan 2010 13:02:48 -0800) it happened "Joel Koltner" wrote in :

Yes, some do, from the 18F14K22 dataheet: 2.12.2 FAIL-SAFE OPERATION When the external clock fails, the FSCM switches the device clock to an internal clock source and sets the bit flag OSCFIF of the PIR2 register. The OSCFIF flag will generate an interrupt if the OSCFIE bit of the PIE2 register is also set. The device firmware can then take steps to mitigate the problems that may arise from a failed clock. The system clock will continue to be sourced from the internal clock source until the device firmware successfully restarts the external oscillator and switches back to external operation. An automatic transition back to the failed clock source will not occur.

Depends on the flavor, but most of the new units have the option and it will jump to an ISR to let you make timing adjustments or fail gracefully/shut down. I usually turn it on to let me set the IO in a known state and then report the error, if possible.

Microchip has come a long way in the past few years. They have even done some changes to their crazy cores to allow high(er) level languages to do things like string handling a bit cleaner. I was a BIG Motorola/Freescale fan, but they don't like to make new parts fit into old sockets. Microchip likes to stick with a pin out and just ups the performance of the guts. I know you can plug a 16C73,

Yep. I know I had people running out of the lab when I found the swapped part. It would probably work fine in 99% of the real world applications (the MCP130), but it doesn't get along well with Motorola's (can't get use to saying "Freescale") bidirectional reset pin. I don't know what we are getting the DS1233s for, but it is a lot less than the labor it is going to cost me to rework 2000 boards, not to mention the customer calls.