Links to tips/advice on creating your own product board w/MSP430?

Thanks Abugs: I figured as much there would be no real 'how-to' guides but what you recommended is what i was looking for. I've been studying the schematics of my 64pin target board and studying the interface of the JTAG connection and such and was curious as to what else was out there.

 

Thanks!

A good starting point are the schematics of the simple zif-socked boards and the experimenters boards. The first for some minimal design/circuitry hints (JTAG, VCC, decoupling) and the other for more complex things like RS232 connection. The schematics are in the board documentations and downloadable from TI.

There's no 'howto' guide because the 'howto' varies with the intended purpose. What's good for one project is a no-go for the other.

If you have a detailed project description, you can get detailed help here or find some hints in the various application notes.

Like the others mentioned, your best bet is to look at any other design using the MSP430. In general, any design with the MSP430 requires:

1) Select the right MSP430 for you. There are many considerations but the MCU selector is a great new feature allowing you to get what you need:

http://focus.ti.com/en/multimedia/flash/selection_tools/mcu/mcu.html

 

1) Supply the correct voltage and make sure to use decoupling capacitors and that they are placed very close to the supply pins. MSP430 supports 1.8V to 3.6V
but some MSP430 derivatives require at least 2.7V for flash reprogramming, so be careful about that. Also, Clock frequency is voltage dependant in some derivatives.

2) Two crystals can be usually added, XT1 and XT2. These require careful layout. The 32kHz crystal app note is very useful in this respect although it sometimes needsto be adapted a bit:
http://focus.ti.com/lit/an/slaa322b/slaa322b.pdf

The main ideas is to build guard rings and prevent any high frequency or disturbing signal from being too close to the crystal to prevent noise.

Selecting the crystal can also be tricky. Make sure to select the right type with the right frequency, load capacitance, etc. A good idea of which ones to use is to look at the BOMs of various ones, go to a supplier and find a similar one. Some MSP430 are adaptable to several load capacitances. Also realize that new MSP430 derivatives include internally low frequency oscillators and then your design might be able to avoid crystals completely.

3) Programming: You can't really use the MSP430 unless you have some interface to program it. JTAG allows you to debug and requires several signals. The bootstrap loaderallows you to download an image but no debugging and depending on the MSP430 can be done with fewer wires than JTAG.

Note that on the RST pin you should add a reset switch unless you really believe you won't need it.

From here it's up to you to connect any module that you're going to use such as USART, GPIO, etc.

GL

Gustavo L. said:

make sure to use decoupling capacitors and that they are placed very close to the supply pins.

You cannot write this large enough!

The engineer who was making the projects before I took over, had the habit of placing all decoupling capacitors into one corner of the circuit sheet. It ended up as a long row of capacitors between VCC and GND. He could as well have placed one single, larger one, since the layouter took this sheet literally and placed all decoupling capacitors in one edge of the PCB, rendering them completely useless. I changed the schematics so that all supply pins are explicitely drawn (in many libraries for digital chips or multiple-OpAmp chips, the supply pins are a separate symbol, implicitely connected and often not placed on the schematics unless explicitely put there) and made sure that  the capacitors are visually connected directly to the supply pins. I still had to tell the layouter several times that he has to obey this proximity in the layout. He used to just look at the layout screen (ignoring the schematics) and there all capacitors are initially ordered in a row.
Now I spam my schematics with comments about why something is to place where and how it has to be routed (e.g. separate ground routings to a common point, width of copper lines for higher currents, distances to gnd for reduced parasitic capacitances etc.

It's a nasty work, especially when using the newer MSPs with 64 or 100 Pins, but it pays if you have to deal with analog voltages or higher currents or high frequencies.

Jens-Michael Gross said:

in many libraries for digital chips or multiple-OpAmp chips, the supply pins are a separate symbol, implicitely connected and often not placed on the schematics unless explicitely put there

That's exactly why I dislike the practice of placing them separately . I understand that with op amps, it's nice because you can better see the function, but usually the connection is simple enough that it just requires one or two capacitors on the VCC. I prefer being explicit with all the pins, unless they're NC.

 

Jens-Michael Gross said:

He used to just look at the layout screen (ignoring the schematics) and there all capacitors are initially ordered in a row.

That is funny. As if when the PCB software starts it knows exactly what you want.
Maybe then he should have left all those components off the board too  :D

GL

Gustavo L. said:

That's exactly why I dislike the practice of placing them separately .

In my own libraries, I don't do it too, normally, but for devices with several identical units, it is the usual way. Else you'd have different symbols for the first and all other units in teh device and couldn't do a gateswap anymore (switching the units if it fits better)
So TTL chips, dual/quad OpAmps or similar devices have a separate power supply symbol.

Gustavo L. said:

He used to just look at the layout screen (ignoring the schematics) and there all capacitors are initially ordered in a row.

That is funny. As if when the PCB software starts it knows exactly what you want.
Maybe then he should have left all those components off the board too  :D[/quote]
Well, if the components are wired to something different, you'll see from the airwires where they belong. But for capacitors between VCC and GND, this isn't obvious.
Good people are hard to find :) No, he does a really good job routing the stuff, but he has some lack of experience with the placement of the parts. Unfortunately they often won't do their job if you place them where they fit best.

Hi Abugs, where can I find the design files of the TI development tools.

The only link I found is brocken.

http://processors.wiki.ti.com/index.php/MSP430_Schematic_and_Layout_documents

I mean the sub link unter example schematics

 

thanks!

Hi Yue,

here's the link again http://processors.wiki.ti.com/index.php/MSP430_Schematic_and_Layout_documents

If tested it and it worked fine. In additon, you can find design files as part of the related tool documentation (http://focus.ti.com/mcu/docs/mcuprodmsptoolsw.tsp?sectionId=95&tabId=1203&familyId=342&toolTypeId=1).

I.e. the design files foe the eZ430-RF2500 are here http://www.ti.com/litv/zip/slac255, those of the MSP-TS430PW28A are here http://www.ti.com/litv/zip/slac472 etc.

Look at the tools to see if some more information is available there.

Rgds
aBUGSworstnightmare

P.S. the latest Eagle library (symbols and footprints for PCB design) is here http://www.ti.com/litv/zip/slac060e