Problem with USB port

I'm in clinical research at a large medical school and a technician who has designed a device for us needs help.

He's working with a FTDI UM245R USB development module with a Microchip PIC microprocessor to input ADC data to a Windows XP pc. The PIC chip, after initializing handshaking with the UM245R, just dumps data to the port. The USB port is configured as a serial port COM3. It worked OK on a breadboard circuit, but now in a hard wired circuit, after registering the USB port, the USB port shows only CTS (clear to send) and null characters. What could the problem be?

Any help would be greatly appreciated. It's a prototype cardiology device and may save many lives.

Thanks in advance

Josh

Reply to
backon
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Hello Josh,

Do you have a schematic you can post somewhere ??

donald

Reply to
donald

Surely at the cost a of a great many dollars? Saving lifes has gotten pretty expensive lately...

Reply to
Jon Slaughter

A particularly scary post... the skill set represented belongs, at best, on sci.electronics.basics :-(

...Jim Thompson

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| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

I got a new motto for there products: "Saving lives, at a price."

Reply to
Jon Slaughter

Which one? I'll tell all my friends and families to stay away.

The technician?

Or kill some.

Reply to
linnix

Dr Josh,

Please do not take this personally.

This is Usenet, there are all sorts of lame ideas posted here.

We (they) didn't know if your post was sincere or not.

Please post a schematic somewhere and we can look at it.

donald

Reply to
donald

OK, guys. I just got off the phone with the cardiologist. This is for real, just a problem with communicating what an electronics technician told the doctor. Sounds like a USB driver issue, which is outside my realm of expertise... I only speak transistors ;-)

Watch for a re-post with DETAILS. The doc needs help. Thanks!

...Jim Thompson

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| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

I have so advised the doctor, by phone. He's going to get direct detail from the electronics technician.

...Jim Thompson

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| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Best to email FTDI I'm using the FIFO version OK and have modified one of their drivers.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
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Reply to
Dirk Bruere at NeoPax

Sorry for my off-color jokes too. But seriously, you might be better off dealing with a single USB micro than a pair of problems (FTDI PIC). Believe me, they will be pointing fingers at each other.

USB is complicated enough without the synchronization issues between two chips. I am currently using AT90USB82,162 and 646. Codes that works under RC stops working under crystal, just as an example.

Reply to
linnix

Pay no attention to JT - he's just a cantankerous old billy goat who's pissed off that people have noticed what a dork Dubya is. And the McCheney^H^H^H^H^H^HCain/Tina Fay candidacy has to be giving him ulcers.

As Jim would say if for example, I was in such a state, "Bwahahaha!" >:->

Good Luck! Rich

Reply to
Richard The Dreaded Libertaria

As much as I hated to defend JT, he followed up and even called the doctor.

Reply to
linnix

Thanks for your cynical replies. We have been working on this device for over

11 years using our own money to fund the development of the device. It's more than 99% complete with the exception of the final interface problem our techncian has with the PC. I am very serious about this and am saddened at the level of discourse here.

If this problem isn't solved, there's no cardiac device.

Dr. Josh Backon snipped-for-privacy@vms.huji.ac.il

Reply to
backon

I am using the Microchip PIC18F2450 for USB communications. In fact, I am making a device that will have a USB connection to the computer (and possibly also a multiport USB hub), and it will communicate with another PIC through a digital isolator using serial interface. This isolation may be an important feature to implement in a cardiac device. I am not familiar with the FTDI device, and I am sure the Microchip devices can do everything it can do (except maybe the security dongle features). I will be completing my design in the next couple of months. The second PIC is used for analog data collection, so the OP's application has much similarity. I'm not an expert at USB, but I do have the device working on Microchip's development module. I'd be interested in learning more and helping if I can.

Paul

Reply to
Paul E. Schoen

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

If it worked on the breadboard then chances are it's an interference issue or connection(assuming the breadboard circuitry is exactly the same and wasn't accidently changed).

If he has the breadboarded circuit then he should try it again to make sure it's not the computer's driver and if it works then check the circuit itself to make sure it is the same as the breadboard. The the problem area should be obvious.

In any case I suspect, as is the general case with doctors now days, that this is more about saving their pocket books rather than saving lifes. (Like a company a friend of mine works for who's motto basically said that saving lifes is most important thing yet makes 10-20x profit on there product)

Reply to
Jon Slaughter

I don't think so. He called me because I have a web site where he could get my phone number. He was more than a little upset with the "fun" we were poking at his post. He has language (and societal viewpoint) differences (Israel) which gave him difficulty communicating to us with the post in the first place; and then with our responses.

I did point out to him that the first order of business was to find out what changed between breadboard and "hard wired".

And we both concurred that our grandchildren handle high tech situations better than we can ;-)

So cut him a break already.

...Jim Thompson

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| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

On Oct 16, 6:24=A0pm, Jim Thompson

I just want to point out that the following text appears on the Microchip PIC website regarding the use of its products in medical devices. Perhaps this is commonplace, (Jim should know), or perhaps there are better chips out there specifically designed / intended for medical use? The OP did not provide any detail on what the device actually does, or whether it relates to life support or safety equipment.

E. SAFETY. GOODS ARE NOT MANUFACTURED OR DESIGNED FOR USE IN LIFE SUPPORT OR SAFETY EQUIPMENT WHERE MALFUNCTION CAN RESULT IN PERSONAL INJURY OR DEATH. YOUR USE OR SALE OF GOODS FOR USE IN SUCH APPLICATIONS IS AT YOUR OWN RISK. YOU AGREE TO DEFEND AND HOLD US HARMLESS FROM ANY RESULTING CLAIM, LOSS, DAMAGE, AWARD, AND COST (NOT LIMITED TO REASONABLE ATTORNEYS=92 FEES).

The site is:

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-mpm

Reply to
mpm

Speaking as someone who has held the title "Heart Monitor Engineer", the circuitry that connects to the patient *must* be made to be safe even when components fail. The rest can be the usual PIC with the usual code *unless* the output controls something that could hurt the patient. This "something" includes nurses who may make wrong decisions based on incorrect readings from the device. I assume that, as a medical device manufacturer, the OP knows all of this. If he doesn't, in any western country he will find it out shortly after seeking approval for his new medical device.

Anyone who works on any sort of medical device will find the phrase "Therac-25" to be familiar and quite chilling. For those who don't work in medicine, read this:

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Frightening, isn't it?

--
Guy Macon
Reply to
Guy Macon

That was a fascinating and informative account about device safety issues that apply to many electronic and software-based products. The product I designed about 15 years ago, known as the Ortmaster, is used to measure time and current values in the testing of reclosers, which are electrical protective devices. The Ortmaster has a rated accuracy of 1%, and is typically calibrated to 1/4%, while the reclosers have an accuracy of about

10% to 20%. So there is considerable room for error without severely compromising safety.

Yet there are many ways in which the equipment could malfunction and give erroneous readings that might cause problems. Luckily, the test technicians usually have a good feel for the accuracy of the test, and will soon recognize an anomaly. In one case, many years ago during early development of the device, a technician said that, even though the display showed 100 amps, it "sure didn't sound like it". Sure enough, a clamp-on ammeter proved that it was really about 120 amps. We traced the problem to a non-linear current transformer and corrected it.

I am now redesigning the device so it can be used on modern non-MSDOS computers running Windows, and equipped with USB ports rather than a parallel port as was previously required. I am adding several new features that should enhance the safety of the device and better assure accuracy, but there is always a chance that a component could fail or an unusual condition could unearth a bug, such as happened with the THERAC25.

I have been advised to consult with a liability attorney as well as my insurance company to determine any special precautions I should take for this new design. I don't think the risks of a calibration error are as great as the possibility of a lethal radiation dose as in the case cited above. But it is possible that an incorrectly calibrated recloser might not coordinate properly with other protective equipment on high voltage distribution lines, and a fault might not be cleared as safely as it should be.

Safeguards will probably need to be implemented that determine at least that a reading is reasonable, and also there will be a requirement that the equipment be calibrated traceable to NIST standards at least once a year. I plan to implement a date-time stamp in the PIC memory that reminds the operator when calibration is due within one or two months, and a stronger warning after a full year has passed. Hopefully that will be enough.

Paul

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Reply to
Paul E. Schoen

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