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Toby Lawrence
Toby Lawrence
02:03
@ThePhoton right, but my confusion is this
assume you have a four layer board, two inner layers are power plane and ground plane respectively
ground on layer 2
you have the PGND and AGND pours on top, according to their layout
if you do thermal vias directly from the PGND pour section, you're connected directly to AGND
so, it would imply that you need to make the layer 2, under the IC at least, a PGND pour itself
but then because you don't want those high power traces going over plane splits, you have to extend the PGND plane to allow it follow all the way until the traces stop or connect to the internal power plane layer
making your AGND internal plane far less contiguous and unbroken
at least that is how I'm seeing it / understanding it
The Photon
The Photon
02:33
@TobyLawrence I'm not sure which traces you mean, exactly (VIN and VOUT nets?).
Toby Lawrence
Toby Lawrence
@ThePhoton yes, those
The Photon
The Photon
Looking at it with this in mind, I think that PGND is the "global" ground, AGND is a "local" ground.
Toby Lawrence
Toby Lawrence
ahhh
The Photon
The Photon
Look at the schematic on pg 1. They distinguis PGND and AGND with different symbols.
But I
But I'm still thinking...
Toby Lawrence
Toby Lawrence
hmm
it would make sense
you have that big AGND pour on the top side for the analog stuff and then you have the noise "chokepoint" of connecting it between those two pins (8 & 9) to the global ground (PGND)
The Photon
The Photon
02:35
Look at the bullet points above the layout. They seem to support this also (but I won't say they're perfectly clarifying it)
"Use large copper areas for power planes (VIN, VOUT, and PGND) to minimize conduction loss and thermal stress."
"Place a dedicated AGND copper area beneath the TPS84250"
Seems to say AGND is a local area, PGND is over the whole board...but not exactly perfectly clear.
Toby Lawrence
Toby Lawrence
yeah
it makes more sense that way... even as like a general "here's how to best keep that ground reference clean for the analog circuitry"
The Photon
The Photon
I think the diagram on the right shows PGND as a full plane layer (fig 41)
Toby Lawrence
Toby Lawrence
yeah, I think I'll approach it the way you're describing it
 
2 hours later…
Anindo Ghosh
Anindo Ghosh
04:10
greetz pplz
 
4 hours later…
jippie
jippie
08:37
good morning @AnindoGhosh
 
8 hours later…
Toby Lawrence
Toby Lawrence
16:40
alright, got that ground pour thing settled
weeee
 
1 hour later…
The Photon
The Photon
17:56
@TobyLawrence Miller Time!
W5VO
W5VO
18:09
@ThePhoton I hate Miller capacitance
Anindo Ghosh
Anindo Ghosh
18:34
@ThePhoton I think you misunderstood the question in this case: electronics.stackexchange.com/q/56970/14004
The Photon
The Photon
@AnindoGhosh It's possible.
Toby Lawrence
Toby Lawrence
bah, just made a noob mistake
changed my board layout before I had ordered a stencil for the prototypes I just got
and I don't have it under version control
blah
The Photon
The Photon
18:55
Top o' the mornin', @DaveTweed
Dave Tweed
Dave Tweed
Hello! Just passing by ...
Anindo Ghosh
Anindo Ghosh
@ThePhoton The chap wanted to use an external 32687 Hz clock, as is suggested for several real-time-clock type purposes in various MSP430 documentation and examples, and as is provided along with each MSP430 Launchpad board for this purpose.
The Photon
The Photon
@AnindoGhosh That information was not in the question when I answered it.
Anindo Ghosh
Anindo Ghosh
@ThePhoton The original question before edits was "I want to use an external crystal for the timer" - same thing - want external crystal instead of internal timing.
The Photon
The Photon
When I answered, it looked like he was asking how to connect the timer peripheral to the uC's main clock, also there was an answer that suggested building a crystal osc from discretes and connecting to TACLK (now deleted).
Also, there's a difference between using an external crystal, and using an external crystal oscillator.
Anindo Ghosh
Anindo Ghosh
19:00
@ThePhoton Yup, there wasn't a mention of an oscillator. Xin / Xout are for a crystal.
@ThePhoton Sorry, I am wrong
The Photon
The Photon
@AnindoGhosh In linked chat you talk about an external clock, not an external crystal
Anindo Ghosh
Anindo Ghosh
@ThePhoton The subject of the question states oscillator.
The Photon
The Photon
Also, I think the key misunderstanding is he thought the datasheet is the whole documentation, and wasn't aware of the User's Guide that I linked.
Anindo Ghosh
Anindo Ghosh
@ThePhoton I do?
@ThePhoton Ahhh I see. I linked to save typing your name :-D
The Photon
The Photon
"The chap wanted to use an external 32687 Hz clock"
Not, The chap wanted to use an external crystal.
Anindo Ghosh
Anindo Ghosh
19:03
@ThePhoton Yup yup. Saw that.
@ThePhoton I got it right in the answer, but was careless in chat. My bad.
The Photon
The Photon
To be honest, it's not clear exactly which OP wants. Maybe he wants to know how to hook up a crystal to the XTAL pins like you answered.
Maybe he wants to know how to connect the timer peripheral to various clock sources.
Maybe he wants both.
Between our two answers, he ought to be able to figure it out.
Anindo Ghosh
Anindo Ghosh
@ThePhoton True.
Toby Lawrence
Toby Lawrence
:P
The Photon
The Photon
@AnindoGhosh Third alternative I just commented on, he might not understand that the Timer is not the same as the system clock.
Anindo Ghosh
Anindo Ghosh
@ThePhoton Also true, going the level of pedantic comprehensiveness of the question (or lack thereof). :-)
Toby Lawrence
Toby Lawrence
19:39
oof, didn't realize I have ~100mb worth of assets for this project
now I'm waiting for this git push to finish, heh
going slowww
 
1 hour later…
Toby Lawrence
Toby Lawrence
20:59
ok, git repo finally created, pushed
weee
Splinky
Splinky
21:13
hi all
@TobyLawrence hi can you help me ?
Toby Lawrence
Toby Lawrence
@Splinky potentially. I may tell you to go post your question on the main site.. but you can certainly ask me it. :)
Splinky
Splinky
@TobyLawrence thx, i want to communicate with pc from PIC but i don't have idea : what should i know to do that
Toby Lawrence
Toby Lawrence
@Splinky this is definitely a candidate for a normal question on the main site, and I bet if you searched for "pc pic communication" you'd find some good questions
generally, you'll talk to your microcontroller using a serial port on your PC
which is the same thing, generally speaking, as a UART port on your microcontroller
so you should search for something like "computer pic serial" or "computer pic uart"
Splinky
Splinky
@TobyLawrence i want to do that with cable after that i need to change to wireless
Toby Lawrence
Toby Lawrence
@Splinky there are relatively cheap TTL to Bluetooth solutions
again, generally speaking, TTL = UART = Serial = RS-232
voltages can be different, but the signalling is the same
so if you make your PIC talk to your computer over serial, there will be plenty of drop-in Bluetooth modules that convert TTL/SerialRS-232/UART to Bluetooth
and you'd have some sort of Bluetooth adapter on your computer that emulated a serial port
Splinky
Splinky
21:22
@TobyLawrence i tried the communication with pic but with an app labview
Toby Lawrence
Toby Lawrence
@Splinky the simplest way to talk to a microcontroller from a computer will be a serial connection over UART
Splinky
Splinky
@TobyLawrence i want to get information from serial port to my application that i need to create
@TobyLawrence but i don't know how get socket working in PIC or how things should work to get all work
Toby Lawrence
Toby Lawrence
@Splinky you'll have to search, either on EE or Google or whatever your favorite search engine is, and find a guide on how to use a UART peripheral on the PIC micro that you're using
Splinky
Splinky
@TobyLawrence i tried that with LabView installed and all working
@TobyLawrence but i need to develope my own application
Toby Lawrence
Toby Lawrence
@Splinky then get a Serial-TTL converter or a USB-TTL converter and get it working with a normal terminal instead of LabVIEW
then write your program and get it working :)
Splinky
Splinky
21:30
@TobyLawrence program with socket communication ?
Toby Lawrence
Toby Lawrence
@Splinky just google for how to access a serial port for the language you want to use
I'm sure there are many, many guides.
Splinky
Splinky
@TobyLawrence ok thx , if u have a simple one plz send me the url
Toby Lawrence
Toby Lawrence
@Splinky nope, I don't. you'll have to learn how to search better. :)
Splinky
Splinky
@TobyLawrence thx a lot :)
Toby Lawrence
Toby Lawrence
@Splinky no problem
Splinky
Splinky
21:34
@TobyLawrence i tried to receive information sent by pic with wireshark but i can't see any thing
Toby Lawrence
Toby Lawrence
@Splinky that's not surprising, because Wireshark isn't for sniffing traffic on serial ports
Splinky
Splinky
@TobyLawrence yes i think he can because with my wireless mouse he can sniff trafic in usb port

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