Electrical Engineering

ConfusedCheese

12:22 AM

Hi, was wondering if anyone could please give me advice on a PIC-PC UART-USB communication problem i'm having?

Shalvenay

@ConfusedCheese fire away

ConfusedCheese

Basically i'm using the PIC16F1619 microcontroller on the curiosity development board and the ADM00559 breakout board for UART-USB communication

i've setup the serial channel according to the datasheet, setting the registers correctly as far I can see

i'm using a program called terminal to see the incoming data

so the communication is up and running

but it doesn't appear to correlate with what I'm sending into MPLAB IDE X

For example if I send 0 I get 0 (correct)

but if I send 2 and then three I get 01 and 111

2 and 3 I get 01 and 111 respectively

which aren't correct?

I'm sending it simply by writing to the TEX1REG
unsigned char character = 3;
TX1REG = character

Any ideas what the problem might be?

really pulling my hair out with it...

Any ideas? :D

Asmyldof

12:49 AM

I don't do PICs

No idea

How are you getting those bits?

ConfusedCheese

Ehmm I'm sending them within my program by writing to the a register that sends it out

and then that is input into my PC via a UART-USB converter

and viewed in a program called 'Terminal'

That just allows you to see incoming bits on a COM port

Asmyldof

then you're not getting bits, you're getting whole bytes

Are your baudrates the same?

ConfusedCheese

Yeah as far I can see

i've set it 9600 on my Terminal program

and according to the datasheet i've set it to 9600 on my PIC too

ww1.microchip.com/downloads/en/DeviceDoc/40001770C.pdf

pg 322

basically you have to set a register pair to a value to determine it

the value is calculated as 52 from the datasheet equation

but it doesn't explicity state how to input for the two

i've put it as 52 for one and 0 for the other

abdullah kahraman

4:54 AM

@ThePhoton Oh, too unfortunate then, I will spend the most time in Prague..

@PlasmaHH Sorry guys, too bad I'm going to Prague and I don't drink

Krishn Shweta

5:19 AM

Morning all

abdullah kahraman

@KrishnShweta morning :)

You are early!

Ooops, sorry, I decremented 3 hours instead of adding :)

Krishn Shweta

Hmm it's 11:00 PM here

11:00 am sorry

abdullah kahraman

~~You mean AM?~~

It is 08:30 here

I miss India..

Krishn Shweta

^_^

Have you visited here?

And you are the second guy who don't drink ( in my friends circle) :-) @abdullahkahraman

abdullah kahraman

5:38 AM

@KrishnShweta Yes, couple of months ago I was in Tuticorin

Krishn Shweta

Yes Tamil Nadu... Well I have to go now sorry. We will talk later.... See you

abdullah kahraman

Bye

Asmyldof

7:18 AM

@ConfusedCheese AsI said, I don't know PICs, so no register help here. But first reason for bytes changing is different settings (start/stop/parity/baud), second is unstable uC clock. To get an accurate baud rate in many uCs that are affordable you need to tune the RC or use a crystal

Although it really seems your PC is lower baud than your PIC if those values are really sent.

so your PIC may be running fast

Or the register could be wrong

Best way to find out is a scope, logic analyser, or if nothing else a frequency counter and sending a continuous stream of 0xAA with one stop bit and no parity should come close to (Baud*4/10), but only if you are sure it really does send an absolute continuous stream

No

Half the Baud rate, no weird fraction

PlasmaHH

8:09 AM

@abdullahkahraman in everyone's life come situations where you reconsider your priorities... ;)

Asmyldof

8:25 AM

@abdullahkahraman Not drinking at all would have been one of the better decisions in my life. Unfortunately, I didn't make it.

abdullah kahraman

:)

Krishn Shweta

2:46 PM

I'm back but without any doubts :-P well surely from tomorrow after 1 week break for studies.

@Asmyldof again I'm applying for one of Job of same syllabus, Exam will be in September. Again late night studies. And one more thing, till now they didn't released previous exams result. Waiting for that.

And no negative marking.... :-) For this and it's a reputed company.

Scott Seidman

3:42 PM

Having just been bitten by a die problem on an AD8422 instrumentation amplifier (http://www.analog.com/media/en/PCN/ADI_PCN_14_0158_Rev_-_Form.pdf) I'd like to replace my ICs with a version that's been resolved by that PCN.

Analog Devices staff tells me that I need a part date coded Feb 2015 or later (while confirming my suspicions that this PCN addresses my problem).

I'm having a bear of a time finding out from Digikey how old their parts are.

In any case, the direct question is "Is it safe to assume that big vendors are selling recent die versions, especially following a PCN of this na…

Just heard from Digikey, actually!! There have three date codes, two of which are acceptable. Now, I just need to figure out how to place the order so I get the latest ones.

The Photon

@ScottSeidman I was going to suggest either 1. use a more hands-on distributor 2. Order direct from Analog 3. Find an alternate PN that does the job.

I would expect Digikey to try to get rid of oldest stock first, so you'll probably get the bad parts if they don't give you some way to specify the required datecode.

Maybe check Mouser, Newark, Avnet, ... to see what date codes they have.

Scott Seidman

@ThePhoton I have some instructions from Digikey now that say to specify the newest date code in an "order note" field near the end of the checkout process. We'll see if that works. Direct from Analog, we're looking at ordering in multiples of 50, and I'm out of pocket.

The Photon

4:15 PM

Anybody have any preferred parts for building negative voltage buck and boost regulators?

Krishn Shweta

@SamGibson hello

SamGibson

Hi! :-)

Krishn Shweta

After long time

You know what you have long life because I believe when we think about someone and unknowingly you will see them so it means that someone will have long life

Just now I thought about you :-)

SamGibson

@KrishnShweta - That's a nice way of thinking of things :-) Sometimes I think of someone and they call me on the phone within a few minutes. Perhaps telepathy does exist...? :-) In the earlier chat I just read that you are doing exams - is that correct?

@ScottSeidman - I would be interested if Digikey do supply you with the newer date code product. It would give me some confidence if the same situation happened to me. I didn't read the PCN yet, but if the issue is bad enough, then who would want to buy the older date code product, with the "problem"?!

Krishn Shweta

4:31 PM

@SamGibson yes....

Nick Alexeev

@ThePhoton What are VIN, and VOUTs? Currents? Are you looking for a single IC to do both positive and negative? Are you looking to make negative from positive? Or, do you start with a negative rail?

SamGibson

@All reviewers of the proposed edit queue: Is there any consensus how to approach proposed edits to very old Q&A? I might even call it "necro-edits"? The ones I've seen proposed have been minor (spelling etc) but valid nevertheless. On the other hand, doing the edit will just push them onto the "front page" which is useless for such old threads, which may already have accepted answers, but in any case are years old... Thoughts?

The Photon

@NickAlexeev Boost circuit: -12 V in, -15 V out, 1 A max output.

Sorry, -18 V out.

Nick Alexeev

@ThePhoton I haven't got a preferred part like that, unfortunately.

The Photon

Buck circuit: -18 V in, -5 to -15 V out (programmatically adjustable, if I get everything I want) ~50 mA

SamGibson

4:36 PM

@KrishnShweta - So, I wish you good luck in the exams :-) A friend of mine in Europe got her exam results on the same day as her last exam in each subject. But here in the UK, there is a long wait (several weeks) after the final exam, before you get the results. I was surprised (but perhaps I should not have been) at how different the exam systems can be in different countries.

Krishn Shweta

Thanks...

Scott Seidman

@SamGibson There are some badges associated with edits, and if I recall correctly, maybe even edits of old posts.

@SamGibson Yup, Excavator and Archaeologist badges

SamGibson

@ScottSeidman - Thanks for that info, and some people will be trying to get those and/or the edit points. It would be easy for me to click "accept" but in the recent cases, I was concerned about possible criticism of accepting such edits, since (as I understand it) an edit to a post pushes it onto the front page of EE.SE. For a thread which is effectively dead, that doesn't seem like a good thing... See what I mean?

The Photon

@SamGibson It's not bad to bring old questions to the front page once in a while. Maybe a new user has joined who can give a better answer than what's already there.

We're not trying to send the asker away happy. We're trying (according to Stack Exchange philosophy) to build a repository of useful questions and answers for people to read and be educated by.

Scott Seidman

@ThePhoton ... or maybe somebody new happens across an old bad question that they want to fix. It seems to be the SE way to encourage tweaking of the archive.

SamGibson

4:47 PM

@ThePhoton - "Maybe a new user has joined who can give a better answer than what's already there." That's an interesting viewpoint which I hadn't considered, thanks.

The Photon

It does tend to be frowned on to flood the front page with edits of old questions and push the new questions out of sight.

But one or two at a time is no problem.

Scott Seidman

That said, it gets a bit annoying when a user is determined to edit old posts and brings a ton of old garbage to the top, but it doesn't happen frequently enough for me to get bent out of shape about it

The Photon

And also, if people want to answer new questions, they should sort the questions by "new" rather than "recent activity".

@ScottSeidman I pretty much always view the site by new questions rather than recent activity.

SamGibson

@ThePhoton @ScottSeidman - Many thanks for those perspectives, they have been very helpful. I won't hesitate (a.k.a "skip") those types of edits in future, after concerns about such "necro-edits" :-) Again, thanks.

The Photon

@NickAlexeev Any experience with LT1070/1071/1072?

Nick Alexeev

5:20 PM

@ThePhoton Negative. No exposure to those.

Nick Alexeev

5:33 PM

@ThePhoton When I need a negative rail, I usually create it from a positive rail using an inverting buck-boost. It can be made adjustable. See for example, fig. 2 in this app note.

PlasmaHH

8:26 PM

Funny, I never noticed that there is some low volume distorted radio reception with my tablet when you have headphones on... never had them on with it I guess

The Photon

@NickAlexeev Unfortunately I am using about all the power I have available on positive rails for other things. The best available power source here is a negative rail.

Scott Seidman

9:29 PM

store.ti.com/ANALOGPRGBOOK.aspx looks like a nice resource, with a free e-version

Shalvenay

10:27 PM

@PlasmaHH LOL, gotta love RF rectification interference. AM I take it?

Asmyldof

10:50 PM

@KrishnShweta All these pre-job-tests, weird to me

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Electrical Engineering